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New Molecular Complexes of Fullerenes C60 and C70 with Tetraphenylporphyrins [M(tpp)] , in which M H2 , Mn, Co, Cu, Zn, and FeCl
Dmitri V. Konarev,[a] Ivan S. Neretin,[b] Yuri L. Slovokhotov,[b] Evgeniya I. Yudanova, Natalya V. Drichko,[c] Yuri M. Shulga,[a] Boris P. Tarasov,[a] Leonid L. Gumanov,[a] Andrei S. Batsanov,[d] Judith A. K. Howard,[d] and Rimma N. Lyubovskaya*[a]
Abstract : New molecular complexes of fullerenes C60 and C70 with tetraphenylporphyrins [M(tpp)] in which M H2 , MnII, CoII, CuII, ZnII and FeIIICl, have been synthesised. Crystal structures of two C60 complexes with H2TPP, which differ only in the number of benzene solvated molecules, and C60 and C70 complexes with [Cu(tpp)] have been studied. The fullerene molecules form a honeycomb motif in H2TPP ´ 2C60 ´ 3C6H6 , puckered graphite-like layers in H2TPP ´ 2C60 ´ 4C6H6 , zigzag chains in [Cu(tpp)] ´ C70 ´ 1.5 C7H8 ´ 0.5 C2HCl3 and columns in [Cu(tpp)]2 ´ C60 . H2TPP has van der Waals contacts with C60 through nitrogen atoms and phenyl groups. Copper atoms of the [Cu(tpp)] molecules are weakly coordinated with C70 , but form no shortened contacts with C60 . Keywords : copper ´ fullerenes ´ porhyrinoids ´ structure elucidation
[a]

The formation of molecular complexes with fullerenes affects the ESR spectra of [M(tpp)] (M Mn, Co and Cu). [Mn(tpp)] in the complex with C70 lowers its spin state from S 5/2 to S 1/2, whereas [Co(tpp)] and [Cu(tpp)] change the constants of hyperfine interaction. ESR, IR, UV-visible and X-ray photoelectron spectroscopic data show no noticeable charge transfer from the porphyrinate to the fullerene molecules.

Introduction
Donor ± acceptor complexes of fullerenes exhibit promising physical properties (superconductivity, and ferromagnetism)[1] and may be important for the study of photoinduced electron transfer.[2] To-date a great number of the molecular compounds with substituted tetrachalcogenafulvalenes,[3] cyclotriveratrylenes,[4] calixarenes,[5] concave aromatic donors,[6] porphyrazine[7] and other molecules,[1b, 8] has been synthesised.
[a] Prof. R. N. Lyubovskaya, Dr. B. P. Tarasov, Dr. L. L. Gumanov, Dr. D. V. Konarev, Dr. E. I. Yudanova, Dr. Yu. M. Shulga Institute of Problems of Chemical Physics Russian Academy of Sciences Chernogolovka, Moscow Region 142432 (Russia) Fax : ( 7) 096-515-35-88 E-mail : lyurn@icp.ac.ru [b] I. S. Neretin, Dr. Yu. L. Slovokhotov Institute of Organoelement Compounds Russian Academy of Sciences 28 Vavilov Str. , Moscow 117334 (Russia) [c] Dr. N. V. Drichko A.F. Ioffe Physical-Technical Institute St.-Petersburg 194021 (Russia) [d] Dr. A. S. Batsanov, Prof. J. A. K. Howard Department of Chemistry, University of Durham South Road, Durham DH1 3LE (UK) Fax : ( 44) 191-384-4737 E-mail : j.a.k.howard@durham.ac.uk
Chem. Eur. J. 2001, 7, No. 12

Fullerene complexes with porphyrins are of particular interest in several aspects, as their electronic structure can vary in a wide range, from co-crystals of essentially neutral, weakly interacting molecules, through charge-transfer complexes, to radical-ion salts. Thus, studies of photoinduced electron transfer in C60 solutions containing octaethyl- or tetraphenylporphyrins, their MgII and ZnII derivatives[9] and in dyad molecules with C60 covalently bonded to porphyrins[10] show the formation of relatively long-lived charge-separated states. Hence the complexes of fullerenes with porphyrins in the solid state may be promising as photoactive materials for xerography and solar energy transducers. Some porphyrins can reduce C60 to yield radical-ion salts, for example, chromium(ii) tetraphenylporphyrin [CrII(tpp)] reduces C60 in toluene/tetrahydrofurane, giving air-sensitive [CrIII(tpp)][C60 .þ] ´ 3 THF,[11] and tin(ii) tetra-p-tolylporphyrin [SnII(tptp)] can reduce C60 in the presence of N-methylimidazole (NMeIm) to form [SnIV(tptp)(N-MeIm)2]2(C60 .þ)2 .[12] Since it is known that radical-ion salts of porphyrins with certain planar p-acceptors (e.g. , manganese(ii) tetraphenylporphyrin and tetracyanoethylene) have a one-dimensional ferromagnetic ordering at helium temperatures,[13] fullerenes may also prove useful as acceptor molecules in the design of new molecular magnetic materials. On the other hand, molecular complexes can be important in building complex inclusion nanostructures, in which the
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principal problem is to control weak, principally van der Waals, interactions. These effects can be also employed for separation and purification of fullerenes, for example, by using appended porphyrins as chromatographic materials.[14] Knowledge of the crystal structures of porphyrin-fullerene complexes can help to understand the porphyrin ± fullerene interaction in a chromatographic column and to optimise the process. Metal complexes with rigidly nonplanar (warped) macrocycles, such as tetra- and octamethyldibenzotetraaza[14]annulenes (TMTAA and OMTAA, respectively), have already proved useful in supramolecular chemistry.[15] They form a variety of complexes with globular molecules, including C60 and C70 , stabilised by the complementarity of curvature between host and guest, for example, a fullerene fitting into the concave surface of the metal-macrocycle complex. Since porphyrins also can adopt warped, as well as planar, conformations, they apparently can perform similar functions as [MII(tmtaa)] and [MII(omtaa)] . Recently, a series of molecular complexes of C60 and C70 with metal (CoII, ZnII, NiII, CuII and FeIII) derivatives of octaethylporphyrin (OEP) were synthesised.[16] However, all of them were found to contain planar, rather than warped, porphyrin systems. The crystal structure of a C60 complex with octakis(dimethylamino)porphyrazine (ODMAP) was reported,[7] as well as the structures, ESR and magnetism of its metal derivatives, [Cu(odmap)]2 ´ C60 ´ 2C6H6 and [Ni(odmap)] ´ C60 .[17] In the latter, a slightly concave (ªdishedº) conformation of [Cu(odmap)] contrasts with more warped, saddle-like conformation of [Ni(odmap)] . Eight structurally characterised complexes of C60 or C70 with tetraphenylporphyrin (H2TPP), its methylated derivatives and [M(tpp)] , all contain practically planar porphyrin systems, closely packed with fullerene cages.[18] Thereupon Boyd et al. concluded that the

R. N. Lyubovskaya et al. van der Waals attraction (dispersion forces) between the curved p surface of a fullerene and a planar p surface of a porphyrin is very favourable for a supramolecular recognition, without the necessity of matching a concave host with a complementary convex guest.[18] In view of these competing models, it is desirable to study a wider variety of fullereneporphyrin combinations. It is also noteworthy, that the first characterised endohedral fullerene was stabilised in a complex with porphyrin, [Sc3N]@[C80][Co(oep)] ´ 1.5 CHCl3 ´ 0.5 C6H6 .[19] We have already prepared molecular complexes of fullerenes with manganese(ii) and cobalt(ii) tetraphenylporphyrins, and their preliminary ESR study is reported elsewhere.[20] In this work we report the synthesis and characterisation of new molecular complexes of fullerenes C60 and C70 with metalfree tetraphenylporphyrin, H2TPP, as well as with manganese(ii), cobalt(ii), copper(ii), zinc(ii), and iron(iii) chloride tetraphenylporphyrinates.

Results
The new molecular complexes 1 ± 12, listed in Table 1, were obtained by the evaporation of solutions containing a fullerene and the corresponding porphyrin compound. The choice of the solvent is crucial. Thus, the fullerene complex of [Mn(tpp)] could be obtained only in CS2 , while the complexes of H2TPP were obtained in benzene and toluene. [Cu(tpp)] and [Co(tpp)] form complexes with fullerenes in all of these solvents, while we could not isolate the complexes of [Ni(tpp)] with C60 or C70 at all. All complexes were isolated as well-formed crystals, but some are unstable, decaying slowly in air and even in argon through the loss of solvent. Two kinds of crystals, 1 and 2, were obtained from C60 and H2TPP ; their

Table 1. Element analysis, absorption bands of solvent in the IR spectra, and the content of a solvent (according to TGA data) in 1 ± 12. Complex C 1 2 3 4 5 6 7 8 9 10 11 12 H2TPP ´ 2C60 ´ 3C6H H2TPP ´ 2C60 ´ 4C6H H2TPP ´ C70 ´ 2C6H6
6 6

Elemental analysis [%]: found (upper)/calculated (lower) H N S accord accord 2.70 2.60 2.14 1.74 1.89 1.95 2.12 1.85 2.18 2.30 accord 2.06 2.24 accord 2.76 2.95 ± 2.63 ing to X-ray ing to X-ray 3.76 3.48 3.68 3.47 4.03 3.78 3.76 3.70 4.10 3.78 ing to X-ray 3.53 3.48 ing to X-ray 6.20 6.26 4.97 5.26 diffraction data diffraction data ± 4.86 4.96 1.61 2.22 ` 0.98 0 ± ± diffraction data ± ± diffraction data 0 0 3.67[b] 3.33[b]

Solvent M n [cmþ1] ä 675 , 1474, 3031 675 , 1474, 3031 675 , 1474, 3031 1508 1508 absent 674 , 2922 absent 674 , 2928
[a]

[%] 6.8 11.4 7.8 N/A 3.0 0 5.7 0 12.8 N/A 12.0 0

[Mn(tpp) ] ´ C70 ´ 1.25 CS [Co(tpp)] ´ C60 ´ 0.5 CS [Co(tpp)] ´ C
70 2

2

[Cu(tpp)] ´ C60 ´ C7H

8

[Cu(tpp)]2 ´ C60 [Cu(tpp)] ´ C70 ´ 2C7H

92.86 93.92 85.14 86.41 89.41 87.93 90.15 90.55 88.80 89.61 89.74 90.30
3

± ± 3.42 ± 4.12 ± 3.90 ± 4.31 ± 3.98 ± 5.85 ± 5.26

8

[a]

[Cu(tpp)] ´ C70 ´ 1.5 C7H8 ´ 0.5 C2HCl [Zn(tpp)(C5H5N)]2 ´ C60 [FeCl(tpp) ]2 ´ C
60

84.27 84.94 ± 83.52
þ1

674 , 2928[a] 702 , 1440, 3080 absent

[a] Toluene absorption bands at 730, 1490 and 3031 cm

coincide with absorption bands of the donor. [b] Cl [%].
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Fullerene-Porphyrin Complexes H2TPP ´ 2C60 ´ nC6H6 stoichiometries differ only by the amount of the crystallisation solvent (n 3 or 4, respectively). It is noteworthy that relative yields of 1 and 2 depend on the crystallisation temperature. Complex 1 is formed at lower temperature, it loses solvent on storage and can be preserved only under an atmosphere, saturated with benzene vapour. Complex 2, which precipitated at higher temperature, is airstable although it contains more solvent than 1. This suggests that here we have kinetic (1) and thermodynamic (2) forms. Thermogravimetric data (see below) also indicates that the solvent is not strongly bound in the crystals. Notably, the mixed-solvent solvate 10 is more stable than its single-solvent analogue 9. In some cases, the presence of other substances was essential for crystallisation of the complexes. Hence, [Zn(tpp)] forms a complex (11) with C60 only in the presence of pyridine (Py). Our preliminary single-crystal X-ray data identified 11 as a molecular complex of fullerene with the mixed-ligand porphyrinate [Zn(tpp)(Py)] ; the Zn atom has a tetragonal-pyramidal coordination environment. Evaporation of solution of [Cu(tpp)] and C60 in toluene leads to the precipitation of the toluene solvate 7, but if ferrocene is added to the solution, then, surprisingly, only the solvent-free complex 8 is precipitated. Thus, ferrocene deters the solvent from inclusion into the growing crystal, without taking its place in the structure ! The compounds were studied using thermogravimetry, and ESR, IR, UV-visible, and X-ray photoelectron spectroscopy ; the crystal structures of 1, 2, 8 and 10 were determined by single-crystal X-ray diffraction. All the complexes are dielectrics with conductivity ` 10þ7 Scmþ1. Thermogravimetry : Compounds 1 and 2 begin to loose solvent at the temperatures of 150 and 120 8C, respectively, while compounds 5 and 7 do so at 170 ± 190 8C. The first and the second toluene molecules in 9 are removed in two distinct temperature ranges, starting at 110 8C and 190 8C, respectively. The onset of the pyridine removal from 11 is much higher at 230 8C. Further loss of mass due to partial decomposition of porphyrins is observed at temperatures upward from 470 8C for H2TPP (in complexes 1 ± 3), 480 8C for [Co(tpp)] in 5, 550 8C for [Cu(tpp)] in 7 ± 9 and [Zn(tpp)] in 11. X-ray crystal structures : Rhombohedral complex 1 and monoclinic 2 are examples of ªquasi-polymorphsº, which differ by the amount of the crystallisation solvent (see above). In both structures the fullerene molecule has no crystallographic symmetry ; the H2TPP molecule occupies an inversion centre and its chromophore moiety is sandwiched between two fullerene molecules (Figure 1). The fullerenes form the shortest contacts with the most electron-rich (nitrogen) atoms of the donor molecule. The N ´ ´ ´ C(C60) distances of 3.02 in 1 and 2.96 in 2 lie at the lower end of the range of van der Waals contacts and well below the ªstandardº contact distance (3.2 ± 3.3 ).[21] Two of the phenyl substituents of the H2TPP molecule form contacts with hexagonal faces of two other C60 molecules, with which they form dihedral angles of 218 in 1, 138 in 2 and the shortest C ´ ´ ´ C contacts of 3.41 ± 3.52 in 1 and 3.36 ± 3.70 in 2. Relative disposition of the
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2605 ± 2616

Figure 1. Molecules in the crystal of H2TPP ´ 2C60 ´ 3C6H6 (1).

two contacting C6 rings resembles the ªparallel-displacedº packing of benzene rings, favourable for quadrupole ± quadrupole interactions.[22] Both structures contain three crystallographically nonequivalent molecules of solvent benzene ; one of them occupies a general position and is stacked to a hexagonal face of the fullerene molecule (forming C ´ ´ ´ C contacts of 3.47 ± 3.74 in 1, 3.33 ± 3.61 in 2). In 1 another benzene molecule occupies å a3 special point and the third one is disordered between three positions related by a threefold symmetry axis ; in 2 both remaining benzene molecules occupy inversion centres. These molecules have no close contacts with the fullerene units. Notwithstanding these apparent similarities, the overall supramolecular organisations of 1 and 2 are drastically different. In 1 the fullerene molecules, with their sixmembered rings facing one another, form a ªhoneycombº motif (Figure 2) with continuous channels. Each channel runs

Figure 2. Crystal packing of 1. C60 molecules are shown as spheres ; phenyl groups and benzene molecules are omitted.

along a crystallographic threefold axis. have their porphyrin cores incorporate channels, while their phenyl groups fill with the benzene of crystallisation.
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The H2TPP molecules d into the walls of the the channels together Each C60 molecule 2607

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contacts five others with centroid ´ ´ ´ centroid separations of 9.81 (two), 9.85 (one) and 9.95 (two). The first three contacts are shorter than in the structure of pure C60 (9.94 at 153 K[23]) and in most of its noncovalent complexes (9.85 ± 10.20 , according to the April 2000 release of the Cambridge Crystallographic Database[24]). A possible explanation of the shortening can be the induced anisotropy of the electron distribution in the fullerene, that is, polarisation effects not cancelling each other in the solid state ;[5] this is more likely when fullerene packing has relatively low dimensionality (cf. in the crystal of C60 each molecule is surrounded by 12 others). However, the bond geometry of the cage gives no indication of such anisotropy. It is also noteworthy that another fullerene-porphyrin complex, [FeCl(oep)] ´ C60 ´ CHCl3 , also displays a short centroid ´ ´ ´ centroid distance, 9.80 .[16] The closest inter-fullerene C ´ ´ ´ C distances in 1, 3.24 , are marginally shorter than twice the van der Waals radius of carbon (3.42 ).[21a] In 2 the fullerene molecules form layers of an hexagonal (graphite-like) pattern, strongly distorted by puckering ; the H2TPP molecule is sandwiched between two C60 molecules belonging to different layers (Figure 3). Each C60 molecule forms only three direct contacts to three others with centroid ´ ´ ´ centroid distances of 9.93 ± 10.14 , so that a 6/6 bond of one molecule is oriented against a hexagonal face of another. Other centroid ´ ´ ´ centroid separations exceed 12 . This framework has channels (filled by the benzene of crystallisation) running parallel to the pseudo-hexagonal fullerene layers (Figure 3). The fullerene molecule is disordered between two orientations (65 :35 %) that are related by a 608 rotation around the molecular threefold axis. The positions of 24 carbon atoms (two opposite six-membered rings and six

R. N. Lyubovskaya et al.

Figure 4. Rotational disorder of a C60 molecule (one hemisphere is shown). Left : in 2, a 608 rotation around the threefold axis. Right : in 8, a 1808 rotation around the axis through the midpoint of 5/6 edges.

atoms directly bonded to either ring) coincide in both orientations, whereas the equatorial belt of the C60 cage between them is disordered (Figure 4). This type of rotational disorder was observed earlier for molecular complexes of C60 with dibenzotetrathiafulvalene[3b] and catena-cyclotriveratrylene.[4b] The final difference Fourier map of 1 also suggests the presence of some orientational disorder that we could not rationalise entirely. The crystal structure of 8 contains no solvent and the [Cu(tpp)] molecule is located in a general position. The C60 molecule lies on a crystallographic twofold axis, which passes through the molecular centroid and the midpoints of two 5/6 bonds, that is, intersects the molecular twofold axis at a 608 angle. Thus the molecule is disordered between two orientations related by the crystallographic axis (Figure 4). This type of rotational disorder, with the disordered C ± C bonds forming six crosses on the surface of a C60 molecule, has also been described earlier.[25] Fullerene molecules are arranged in nonlinear columns (chains), parallel to the z axis of the crystal lattice, whereby each fullerene molecule has contacts to two others with a centroid ´ ´ ´ centroid separation of 9.92 , which is longer than in 1 but still close to the lower limit of the usual range of such distances (see above). The resulting short interfullerene C ´ ´ ´ C distances (3.1 ± 3.4 ) involve 5/6 bonds of the contacting cages, as in [K([18]crown-6)]3 ´ C60 ´ PhMe, in which such contact was regarded as a shift towards formation of one-dimensional polyfulleride by [22] cycloaddition of the 5 :6 ring connections.[1c] The fullerene columns are separated from one another by pairs of warped [Cu(tpp)] molecules (Figure 5). The shortest intermolecular distances N ´ ´ ´ C(C60) of 3.36 and Cu ´ ´ ´ C(porphyrin) of 3.28 are

Figure 3. Crystal structure of H2TPP ´ 2C60 ´ 4C6H6 (2). Top : a layer of C60 molecules, parallel to the (1 0 0) plane. Bottom : a view along this layer. Only major orientations of the C60 molecules are shown.

Figure 5. Molecular packing in [Cu(tpp)]2 ´ C60 (8), projection on the plane (1 þ 1 0).
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Fullerene-Porphyrin Complexes characteristic of van der Waals interactions, and there are no shortened Cu ´ ´ ´ C(C60) contacts. The packing motif is broadly similar to that of [MII(oep)] ´ C60 ´ C6H6 ´ CHCl3 ,[16] but in the latter the porphyrin chromophores remain planar and the fullerene cage is surrounded (ªsolvatedº) by its ethyl substituents. In 8, the [Cu(tpp)] has no such flexible substituents and can maximise its van der Waals interactions with the fullerene by making the chromophore itself concave. In the structure of 10, the C70 molecule has no crystallographic symmetry and is fully ordered. Two crystallographically nonequivalent [Cu(tpp)] molecules are located at inversion centres ; each of their phenyl groups is disordered between two orientations with nearly equal occupancies and has no shortened contacts with the C70 . One independent toluene molecule occupies a general position, another one is located at an inversion centre ; both molecules are disordered. The crystal contains a nonstoichiometric amount of trichloroethylene ; its molecule is situated in a general position and is disordered between three orientations with the total occupancy of approximately 0.5. Ellipsoidal C70 molecules form zigzag chains parallel to the y axis, the same structural motif as found in [Ni(odmap)] ´ C60[17] and H2TPP ´ C60 ´ 3 PhMe.[18a] Each C70 molecule is adjacent to two others, with close van der Waals contacts (C ´ ´ ´ C 3.2 ± 3.4 ) and centroid ´ ´ ´ centroid separations of 10.14 and 11.13 . Each [Cu(tpp)] chromophore is sandwiched between two fullerene molecules (Figure 6), whose two 6/6-type bonds ªgº (adjacent to the equatorial belt of the molecule, see Scheme 1) complete the square-planar coordination of the copper atom to a distorted (tetragonally elongated) octahedral one ; the Cu ´ ´ ´ C(C70) distances varying from 2.88 to 3.03 . On the other hand, each C70 is coordinated (through the g-type bonds of the same hemisphere) with two [Cu(tpp)] chromophores, whose planes form a dihedral angle of 398 between them and are nearly parallel (inclined by 78 and 108) to the long axis of the ellipsoidal C70 . The same ªside-onº approach of C70 to porphyrin was observed in [Zn(tpp)] ´ C70[18a] and in the series of isostructural complexes [MII(oep)] ´ C70 ´ C6H6 ´ CHCl3 (M Co, Ni and Cu).[16] In the latter the long axis of the C70 is inclined by about 168 to the porphyrin plane. This arrangement contrasts with the ªend-onº coordination of C70 with metals ; this occurs where back-bonding is significant.[26] The crystal lattice of 10 and the positions of the fullerene and porphyrin units therein are practically identical with

2605 ± 2616

Scheme 1. Notation of chemically nonequivalent bonds in C H2TPP or [Cu(tpp) ] .

70

and in

Figure 6. Chain of C70 and [Cu(tpp)] molecules in the crystal of [Cu(tpp)] ´ C70 ´ 1.5 C7H8 ´ 0.5 C2HCl3 (10).
Chem. Eur. J. 2001, 7, No. 12

those of [Zn(tpp)] ´ C70 .[18a] However, the latter structure was not reported to contain any solvent of crystallisation. Our analysis of the crystal packing in [Zn(tpp)] ´ C70 revealed substantial voids. Taking into account the relatively high discrepancy factor R 10.2 % and residual electron density (1.9 e þ3), one may guess that the crystal in fact does contain some solvent (toluene ? ), which was not identified because of intense disorder, similar to that actually observed in 10. The latter structure was refined to a similar R of 10.0 %, but on nearly double the number of reflections. It is also interesting to compare the structures of 10 and [Cu(tmtaa)] ´ C60 ,[15d] in which the metal-macrocyclic system is also sandwiched between fullerene molecules, but has a rigid saddle shape that matches the fullerene curvature. This improves the overall interaction between the two, but at the same time weakens the Cu ´ ´ ´ C60 interactions (the shortest Cu ´ ´ ´ C distances are 3.18 and 3.37 ). Fullerene molecules in [Cu(tmtaa)] ´ C60 form corrugated layers (as in 2) rather than chains (as in 10), and each C60 molecule has contacts to five others (as in 1), but at longer centroid ´ ´ ´ centroid distances of 9.96 ± 10.08 . The C60 and C70 geometry in the complexes is in good agreement with that in pure fullerenes or their neutral molecular complexes[23, 27] (see Table 2, notation in Scheme 1). Bond lengths in the porphyrin and metal-porphyrin chromophores also remain essentially the same as in pure components and their solvates[28±32] (Table 2, Scheme 1) and fit an approximate local fourfold symmetry. However, neither is true for conformation of the porphyrins. Generally, a porphyrin system has two stable conformations : the planar and the warped (saddle-like) ; the degree of puckering may be described by the root mean square (rms) deviation (D) of the atoms from the mean plane. In the solid H2TPP[28] or [Cu(tpp)] ,[31] both chromophores are warped : D 0.19 and 0.21 , respectively. The puckering is further enhanced (D 0.42 ) in the diprotonated porphyrin cation of H4TPP(ClO4)2 ´ C6H6 .[30] In contrast, both H2TPP and [Cu(tpp)] have planar conformation (D 0.01 ) in 1:2 molecular complexes with m-xylene.[29, 31] In the complexes in which the porphyrin is sandwiched between two fullerene molecules, the chromophores are almost as planar (D 0.053 in 1, 0.042 in 2, 0.014 and 0.025 in two independent [Cu(tpp)] molecules of 10), whilst in the absence of such packing in 8 the [Cu(tpp)] molecule remains as puckered (D 0.263 ) as in solid [Cu(tpp)] . The similar ªwarpedº conformation was observed by Hochmuth et al. in the nickel porphyrazinate complex with fullerene [Ni(odmap)] ´
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Table 2. Average bond lengths, angles and root mean square deviations of atoms from the mean plane (D) in the porphyrin chromophore. Estimated standard deviations for the bond lengths and angles are 0.001 ± 0.01 (M þ Nto CþC) and 0.1 ± 1.08, respectively, for the ordered moieties ; up to 0.02 and 3.08 for the disordered ones. 1 D [] bond lengths [] i ii iii iv v bond angles [8] i±i i ± ii i ± iv ii ± iii ii ± iv iv ± iv iv ± v 0.053 1.378 1.439 1.353 1.405 1.51 107.2 108.9 125.5 107.4 125.5 126.2 116.9 8 D [] bond lengths [] i ii iii iv v vi bond angles [8] vi ± i i±i i ± ii i ± iv ii ± iii ii ± iv iv ± iv iv ± v 0.263 1.378 1.442 1.355 1.396 1.498 1.983 127.0 105.8 110.0 125.1 107.0 124.6 123.4 118.2 1 5/6 bond 6/6 bond Bond a b c d e f g h 1.47 1.35 Type 5/6 6/6 5/6 6/6 5/6 5/6 6/6 6/6 2 0.042 1.376 1.443 1.358 1.405 1.501 107.6 108.8 126.2 107.4 125.0 125.3 117.3 A 0.014 1.384 1.440 1.358 1.393 1.491 2.001 127.4 105.2 110.4 125.4 107.0 124.2 124.3 117.8 C60 bond lengths [] 2 major 1.47 1.36 C70 bond lengths [] Number in molecule 10 10 20 10 20 10 20 5 10 H2TPP
[28]

H2TPP ´ (m-xylene) 0.010 1.377 1.443 1.354 1.391 1.515 106.1 109.9 124.5 107.0 125.5 126.9 116.5 [Cu(tpp)]
[31]

[29] 2

H4TPP(ClO4)2 ´ C6H 0.417 1.390 1.431 1.365 1.414 1.491 110.3 106.1 125.9 108.7 127.9 123.2 118.4

[30] 6

0.189 1.350 1.438 1.361 1.403 1.514 108.8 108.7 126.0 106.9 125.1 125.1 117.4 B 0.025 1.376 1.440 1.358 1.397 1.503 2.009 127.1 105.6 110.4 125.8 106.8 123.8 124.0 118.0

[Cu(tpp)] ´ (m-xylene)2 0.008 1.381 1.435 1.351 1.391 1.500 1.997 127.3 105.4 110.2 125.8 107.1 124.0 123.9 118.1 C
[a]

[32]

0.214 1.383 1.447 1.337 1.368 1.489 1.980 125.9 107.9 107.9 126.5 108.1 125.3 123.0 118.5 8 1.45 1.40 C70 ´ 6S 1.44 1.38 1.46 1.37 1.46 1.44 1.40 1.48
[27b]

minor 1.50 1.32 10 1.45 1.37 1.46 1.37 1.45 1.45 1.40 1.49

60

1.46 1.40

8

[a] Gas-phase electron diffraction, ref. [27a].

C60 , in which (as in 8) only normal van der Waals contacts Ni ´ ´ ´ C60 exist.[17] ESR spectra : The ESR spectra of [Mn(tpp)] , [Co(tpp)] , [Cu(tpp)] and their complexes with C70 at 77 K are shown in Figure 7. The spectra of the C60 complexes with the same donors are similar. It is noteworthy that the ESR spectra of some complexes show a narrow weak signal with g 2.0022 2610

and DHpp 1.5 G (300 K), which persists almost without changes down to 77 K. This signal, which was observed also in the spectra of the starting fullerenes, can be attributed to oxygen-containing impurities,[33] most probably to C120Oþ.[33c] Its intensity depends strongly on the conditions of preparation, purification and storage of fullerenes and the complexes. Pure [Mn(tpp)] has a high spin state (S 5/2) and an anisotropic ESR spectrum (gc 5.9, gk 2.0) with a hyperfine
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2605 ± 2616 [Cu(tpp)] at 77 K (Cu, I 3/2, gc 2.071, B þ 29 á 10þ4 cmþ1, gk 2.193, A þ 202 á 10þ4 cmþ1)[35] and of 7 (gc 2.050, gk 2.190, A þ 168 á 10þ4 cmþ1) are even more similar. For 9 (gc 2.058, gk 2.176, A þ 170 á 10þ4 cmþ1) and 10 the values of gc and gk remain almost unchanged, but the intensity of the perpendicular component increases (Figure 7 f). This indicates a less anisotropic interaction of the spin orbitals, probably due to weak Cu ´ ´ ´ fullerene coordination, such as we observed in the crystal structure of 10. Earlier, changes in the ESR spectrum of the solid porphyrazine complex [Cu(odmap)]2 ´ C60 ´ 2C6H6 , compared with [Cu(odmap)] in solution, were attributed[17] to similar weak Cu ´ ´ ´ C60 interactions (as well as to stacking porphyrin ´ ´ ´ porphyrin interactions which do not exist in the crystal of 10). Pure [FeCl(tpp)] has a high-spin (S 5/2) state and an anisotropic ESR spectrum with g 5.7 and DHpp 300 G at room temperature ; the signal is narrowed to 200 G on cooling down to 77 K. The spectrum of its complex 12 is almost the same, with g 5.63 and DHpp 330G at room temperature and g 5.78 and DHpp 200 G at 77 K, indicating the absence of FeIII ´´´ C60 coordination, in agreement with the X-ray structural data.[16] IR spectra : The IR spectra of all the complexes are a superposition of the vibrational bands from starting (metal)porphyrins, fullerenes and solvents. The typical spectra of 5, 6 and [Co(tpp)] are presented in Figure 8. The vibration

Figure 7. The ESR spectra of a) [Mn(tpp)] , b) 4, c) [Co(tpp)] , d) 6, e) [Cu(tpp) ] and f) 9 at 77 K in argon atmosphere. Arrows show the position of g 2.0022.

structure (HFS) due to the interaction between the unpaired electron and the 55Mn nucleus (I 5/2).[34] Using a solid sample with high spin concentration, we could not observe the HFS (Figure 7a). In complex 4 with C70 , the spin of [Mn(tpp)] is lowered to 1/2. A similar spin-lowering occurs upon the formation of the nitric oxide complexes [MnII(tpp)(Xþ)(NO)] (X Cl, CH3CO2), which show a six-line isotropic ESR spectrum with a 55Mn (I 5/2) hyperfine splitting characteristic of a low spin [d5] (S 1/2) state of [MnII(tpp)] .[34] The spectrum of 4 in argon atmosphere at 77 K (Figure 7b) is a broad line with g 2.002 and DHpp 300 G, but a ten-minute exposure of the sample to air reveals the HFS (six lines with the A1 intervals of 83 G). Evidently, a partial oxidation of [MnII(tpp)] to diamagnetic [MnIII(tpp)] takes place, the concentration of spins decreases and, therefore, HFS of the unpaired electron and 55Mn nucleus is revealed. Incidentally, this confirms that the unpaired electron is located basically on the d orbital of MnII and interacts with its nucleus intramolecularly. The exposure of 4 to air for a few hours results in the disappearance of the ESR signal due to complete oxidation of the paramagnetic MnII. The [Co(tpp)] and [Cu(tpp)] units in complexes 5 ± 10, as the corresponding pure porphyrins, have a low-spin state (S 1/2) and ESR spectra with the resolved HFS and g-factor anisotropy. The effect of the complexation is practically confined to the hyperfine interaction (HFI) parameters, which are most sensitive to local interactions on the metal centres. ESR of pure [Co(tpp)] is observed at 77 K (59Co, I 7/2, gc 3.322, B 395 á 10þ4 cmþ1, gk 1.798, A 197 á 10þ4 cmþ1, see Figure 7c), but not at room temperature (due to short relaxation times[35]), while the spectra of 5 and 6 (Figure 7d) are observed even at room temperature. Both complexes display a broad intense asymmetric line with hgi 2.4 and DHpp 500 ± 600 G, resulting from the overlap of parallel and perpendicular components of the spectrum of a polycrystalline sample. The HFS due to the interaction of the unpaired electron with the 59Co nucleus (I 7/2) is also observed above a broad signal, as eight components with a separation of 170 G. The g factors change substantially relative to pure [Co(tpp)] , both HFI constants A and B decrease, suggesting weak [Co(tpp)] ´ ´ ´ fullerene interactions, probably similar for C60 and C70 . The ESR spectra of [Cu(tpp)] in the complexes 7 ± 10 with C60 and C70 also correspond to the low-spin state with the retention of the gc and gk values. The ESR spectra of pure
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Figure 8. The IR spectra of 5 (top), 6 (middle) and [Co(tpp) ] (bottom) in KBr pellets. The C60 and C70 absorption bands are marked by asterisks.

frequencies of C60 at 1429 cmþ1 and C70 and 1430 cmþ1, the most sensitive to the alterations of electron density,[36] remain unchanged within ô 1 cmþ1, indicating the absence of a charge transfer in the ground state. The porphyrin bands in the
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complexes also coincide with those of the pure porphyrins. Larger shifts (up to 5 cmþ1) upon the complex formation were observed for CþC (700 ± 800 cmþ1) and CþH vibrations (3000 ± 3100 cmþ1) of phenyl groups and NþH vibrations of H2TPP at 3320 cmþ1. UV-visible spectra : Van der Waals interactions of porphyrins with fullerenes failed to generate additional bands in the UVvisible spectra of any of the studied complexes except 4, which shows an intense absorption band at 487 nm (Figure 9) that is

R. N. Lyubovskaya et al. [Co(tpp)] (in KBr pellet) shows that the spectrum of 5 (263, 340, 433 and 533 nm) is a superposition of the slightly shifted bands of [Co(tpp)] (429 and 527 nm) and C60 (262 and 340 nm). However, the absorption bands of [Co(tpp)] in 5 are anisotropic and have the maximum intensity in the R2 and R3 polarisations, suggesting that the planes of the porphyrin chromophores are almost parallel to the R2 and R3 directions of the crystal. The intensity of a broad weak band near 750 nm in the R3 polarisation is dependent on the polarisation and can be attributed to a [Co(tpp)] 3 C60 charge transfer (CT) in the direction normal to the porphyrin plane. The spectra of other complexes (Table 3) contain no pronounced CT bands, while

Table 3. UV-visible spectra. fullerene C60 C70 H2TPP 1 [Mn(tpp)] 4 [Co(tpp) ] 5 6 [Cu(tpp) ] 9 260, 344, ± 261, ± 337, ± 263, 256, ± 263, Absorption bands [nm] porphyrin ± ± 432, 438, 426, 487, 429, 433, 431, 427, 432,

340 388, 501 336 387 340 337 339

Figure 9. The UV-visible spectra of a) 4 and b) C [Mn(tpp)] absorption band is marked by an arrow.

70

in KBr matrix. The

523 523 580, 620 620 527 533 526 547 551

not present in the spectrum of pure [Mn(tpp)] . This band may correspond to the d ± d transition for MnII, which is forbidden in the high-spin state of the free [Mn(tpp)] , but becomes allowed as the spin lowers to 1/2 in the complex. Similar spinlowering in [MnII(tpp)(CNþ)(NO)] (see above) is also accompanied by the appearance of a new intense band at 490 nm (toluene glass, 77 K).[34] The UV-visible reflectance spectra from single crystals of 5 were measured in three different polarisations of light (parallel to the crystal faces) and the absorption spectra were derived therefrom by the Kramers ± Kronig transformation. A comparison (Figure 10) with the absorption spectrum of

showing bathochromic shifts (up to 6 nm) of the Soret and Q bands of the porphyrin units compared to pure porphyrins. Similar effects in solution were observed earlier for cyclophane-type dyad compounds,[10b] in which a C60 fullerene and an H2- or zinc(ii) diphenylporphyrin moieties are linked by covalent bridges and, therefore, are constrained to a face-toface contact at 3.9 ± 4.1 . There too, the UV spectrum was the superposition of the components spectra, in the visible region the Soret bands underwent a bathochromic shift and a strong intensity decrease, whereas the Q bands were less affected. The latter was taken as an indication that the electronic structure of the porphyrin is strongly perturbed by the fullerene, but not vice versa. X-ray photoelectron spectra : The N 1s, Co 2p3/2 and Cu 2p3/2 peaks of the donor units in the complexes (Table 4) are only slightly shifted relative to the starting porphyrins, indicating

Table 4. X-ray photoelectron spectra. DC1s [eV][a] C60 H2TPP 2 [Co(tpp) ] 5 [Cu(tpp) ] 7 9 1.9 2.70 2.05 2.30 2.05 2.20 2.20 2.10 N1s [eV]
[b]

M2p

3/2

[eV]

[b]

Figure 10. The UV-visible absorption spectra : a) of a single crystal of 5 for three polarisations of light R1±3 (parallel to the crystal faces) ; b) of [Co(tpp) ] in a KBr pellet.

± 400.0, 398.2 399.9, 398.2 399.0 398.8 398.2 399.0 398.7

± ± ± 780.6 780.3 934.6 934.6 934.2

[a] Halfwidth of the C 1s peak. [b] Peak positions (ô 0.2 e), M Co or Cu.
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Fullerene-Porphyrin Complexes no significant redistribution of electron density. The C 1s peak halfwidth of 2 is narrower than that of pure H2TPP (Figure 11), and both display satellite structures at higher energies relatively to the basic C 1s. This satellite structure is narrower for H2TPP than for 2, probably because of their different

2605 ± 2616 absence of charge transfer from [Mn(tpp)] to C70 in 4 and lowspin state of [Mn(tpp)] therein, frustrate the hope to obtain a molecular ferromagnet similar to the [Mn(tpp)][TCNE] ´ 2 PhMe salt, in which a one-dimensional ferromagnetic ordering was associated with the presence of the tetracyanoethylene (TCNE .þ) radical anion and the high-spin [MnIII(tpp)] .[13] On the other hand, the complexes described herein can not be regarded as random combinations of essentially inert components. Rather they belong to the (yet insufficiently understood) class of molecular complexes in which a cumulative effect of weak p ± p, electrostatic (multipole) and dispersion forces results in a substantial mutual affinity of the components without any appreciable charge transfer or alteration of the covalent bond geometry ; C6H6 ´ C6F6 can be regarded as a typical complex of this class.[22] An indication of such affinity is the persistence of a few types of supramolecular organisation (synthons) in a variety of complexes. Thus, a zig-zag chain of fullerene cages interleaved with planar porphyrins can be discerned in every 1:1 fullereneporphyrin complex previously reported.[17, 18] Compolexes with a 1:2 ratio display the same motif with each porphyrin molecule replaced by two (also planar), stacked face-toface.[16] The former motif exists in 2 and 10 (and in a cyclic variety, in 1) ; the latter in 8, except that there the porphyrins are warped. In every case, fullerene is aligned against the centre of the porphyrin chromophore, whether the latter is occupied by a metal atom or not. 1:1 complexes of C60 or C70 with rigidly warped TMTAA or OMTAA systems, also comprise mixed column. Likewise, both synthons of fullerene-fullerene type, namely, a zig-zag chain of closely contacting fullerene cages and a corrugated layer thereof, which are observed in fullerene-porphyrin complexes, also exist, for example, in [Ni(tmtaa)] ´ C60 and [Ni(omtaa)] ´ C60 ´ 2CS2 , respectively.[15b] This view is further corroborated by our spectroscopic and ESR studies ; these indicate small but significant effects that can be attributed to the mutual influences of the fullerene and porphyrin p systems and correlate with the crystallographic data. Thus, N(porphyrin) ´ ´ ´ C(fullerene) contacts marginally shorter than the sum of the van der Waals radii, such as observed in 1 and 2, are a general feature of fullerene complexes with metal-free porphyrins and were explained[18] by a favourable van der Waals attraction between curved and planar p-surfaces. Changing of the porphyrin conformation from warped to planar on complexation is also noteworthy. Of course, a molecule that is nonplanar in the gas phase can adopt a flat conformation in a crystal in order to maximise the packing density. However, here the nonplanar conformation is displayed in crystals of pure porphyrins and, furthermore, planarisation of the porphyrin chromophore is unlikely to facilitate its co-crystallisation with a spherical fullerene molecule. In fact, conformationally flexible molecules often adopt folded conformations to ªwrapº around a fullerene cage, for example, a tetrathiafulvalene derivative in DBTTF ´ C60 ´ C6H6 .[3b] Therefore the porphyrin planarisation may be due to intermolecular interactions rather than packing requirements. Rigid saddle-shaped macrocyclic complexes [MII(tmtaa)] and [MII(omtaa)] can accommodate a fullerene
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Figure 11. X-ray photoelectron C 1s spectra of H2TPP (dashed) and 2 (solid line), and a portion thereof multiplied eight times.

nature : the former originates from the p ± p* transition in phenyl groups, the latter mainly from the losses associated with the excitation of p plasmons of the C60 .[37] The halfwidth of the C 1s peaks for [MII(tpp)] in fullerene complexes is also smaller than for the pure donors (see Table 4), while the relative integral intensity and the halfwidth of the satellite peak are larger in the former.

Discussion
On the strength of IR, ESR, UV-visible and X-ray photoelectron spectroscopy, conductivity and crystallographic data, compounds 1 ± 12 are essentially molecular complexes without any notable charge transfer. This could be predicted for 1 ± 3 and 5 ± 10, since the oxidation potentials of H2TPP, [Cu(tpp)] (both 1.00 V) and [Co(tpp)] ( 0.54 V) (in benzonitrile, vs SCE[38]) are very positive compared to the reduction potentials of C60 and C70, þ 0.44 and þ 0.41 V, respectively (in dichloromethane, vs SCE[39]). However, Eox of [Mn(tpp)] (þ 0.23 V, acetonitrile, vs SCE[40]) seems close enough to the Ered of C70 to expect a significant CT in 4, which does not occur. One possible explanation is that nonpolar solvents were used. Previously it was shown[12, 13] that even such strong donors as [Cr(tpp)] and [Sn(tptp)] can not reduce C60 to a radical anion in nonpolar solvents, notwithstanding much more negative redox potentials (Eox þ 0.86 and þ 1.17 V, respectively). The formation of radical-anion salts was observed in polar media like tetrahydrofuran or Nmethylimidazole, which stabilises [Cr(tpp)] and [Sn(tptp)]2 cations. Unfortunately, we were unable to prepare complexes of [Mn(tpp)] with fullerenes in the CS2/THF mixture (1:1) to corroborate this hypothesis. In the case of [Co(tpp)] and C60 , only a THF solvate of [Co(tpp)] without C60 was obtained. The other reason for a low extent of charge transfer in the complexes may be the low efficiency of HOMO ± LUMO overlapping between porphyrin and fullerene moieties. The
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molecule in their concave surface and achieve a better match of curvature without any change in the macrocycle shape.[15] A larger area of an host ± guest contact evidently maximises the total van der Waals interaction. However, these macrocycles (and the warped porphyrin in 8) do not form such short contacts with fullerenes, as the planar porphyrins do. Also, as could be expected, maximisation of the fullerene ± macrocycle interaction diminishes the fullerene ± fullerene interactions. In ªdisparateº fullerene-porphyrin complexes, distances between the centroids of C60 molecules are often shorter than the doubled van der Waals radius of 5.0 ,[41] especially in 1 and [FeCl(oep)] ´ C60 ´ CHCl3 (see above). In the better matched fullerene-ªsaddleº complexes, C60 molecules lie further apart, or are completely insulated from direct contacts. The contacts of a copper atom with two electron-rich fullerene 6/6 bonds in 10 is of particular interest. A distorted octahedral coordination with four strong bonds and two weak ones (trans to each other) is very common for CuII due to the Jahn ± Teller effect. A survey of the October 1999 release of the Cambridge Structural Database[24] shows that the Cu ´ ´ ´ C(olefin) distances are distributed in two distinct ranges, namely 1.9 ± 2.1 (strong h2 coordination) and 3.1 ± 3.3 (nonbonded contacts), with a few exceptional distances of 2.9 ± 3.0 , that is, slightly shorter than van der Waals contacts (Figure 12). The Cu ´ ´ ´ C(C70) distances in 10 (2.88 ± 3.03 )

R. N. Lyubovskaya et al. and [Ni(odmap)] ´ C60 .[19] As the C70 molecule is disordered in 8 and ordered in 10 (and also in all three [MII(oep)] ´ C70 ´ C6H6 ´ CHCl3 complexes), one can suggest that the additional metal ´ ´ ´ fullerene coordination may be responsible for the C70 ordering. However, in the structure of [Zn(tpp)] ´ C70 the C70 is also disordered. Metal(ii) tetraphenylporphyrins form complexes with C70 more readily than with C60 (e.g,. 9 precipitates even from dilute solutions), while the opposite is true for substituted tetrathiafulvalenes and aromatic hydrocarbons.[11] The reasons of this may be better steric compatibility between [MII(tpp)] and C70 . Thus, [Ni(omtaa)] can accommodate C70 in the same way as smaller [Ni(omaa)] accommodates C60 .[15d] Another reason may be the higher propensity of C70 for d ± p metal ± fullerene interactions : although the Cu ´ ´ ´ C70 interactions in 10 are rather weak, they compare favourably with the absence of any such interactions in the C60 complex 8. Whatever the origin of the effect, it may be utilised to separate chromatographically C60 from C70 by using appended metal tetraphenylporphyrins.

Conclusion
New molecular complexes of fullerenes C60 and C70 with tetraphenylporphyrin, metal(ii) tetraphenylporphyrins and iron(iii) tetraphenylporphyrin chloride were obtained and characterised by IR, UV-visible, ESR, and XPS data. All the complexes obtained are molecular ones without charge transfer in the ground state. Single-crystal structures of four molecular complexes showed different packing of fullerene molecules varying from columnar to three-dimensional ones. In all compounds the interaction between the components is mainly of van der Waals nature, with probable contribution of C60 ´ ´ ´ N(H2TPP) p ± p interactions and secondary d ± p coordination [M(tpp)] ´ ´ ´ C70 ; this last coordination mode slightly affects the electronic state of [M(tpp)] . Indirect evidence for a specific [M(tpp)] ± fullerene interaction was provided by ESR spectroscopy : the effect of complexation with fullerenes on the ESR spectra of metal tetraphenylporphyrins decreases in the succession [Mn(tpp)] b [Co(tpp)] b [Cu(tpp)] , becoming negligible for [FeCl(tpp)] . The difference in nonbonding interactions of [Cu(tpp)] with C60 and C70 observed in the complexes may be useful for chromatographic separation of these fullerenes. According to the UV-visible spectra, the charge transfer can probably take place in the photoexited state of the complexes, affecting the whole set of electric and magnetic properties of the complexes formed. Studies of photoinduced electron transfer in the solid state of the complexes, which are of particular interest for their optical properties, are presently under way.

Figure 12. Histogramm of bonding (white columns) and nonvalent (grey) CuþC(olefin) distances from CSD data. Secondary bonding distances in 10 are shown as thin lines.

belong to the latter category and can be described as an additional coordination (secondary bonding), which is fairly common for d elements and was reported earlier for a variety of fullerene complexes. Similar interactions of a metal atom with 6/6 bonds of C60 (M ´ ´ ´ C 2.67 ± 3.32 ) were observed in two isomorphous complexes [MII(oep)] ´ C60 ´ CHCl3 (M Co and Zn).[18] In a series of isomorphous compounds [MII(oep)] ´ C70 ´ C6H6 ´ CHCl3 (M Co, Ni and Cu)[18] the metal atom has an additional coordination with only one carbon atom of the C70 cage ; the Cu ´ ´ ´ C distance of 2.92 (cf. Co ´ ´ ´ C 2.80 and Ni ´ ´ ´ C 2.83 ) is close to those in 10. Metal ´ ´ ´ fullerene interactions of the same order were also found recently in [Zn(tpp)] ´ C70 (2.89 ),[20a] [Fe(tpp)]B(C6F6)4 ´ C60 (2.63 )[20b] 2614

Experimental Section
Materials : [Mn(tpp)] was synthesised from H2TPP and MnCl2 ´ 4H2O and purified as described earlier, its elemental analysis, ESR and IR spectra coincide with the reported data.[42] H2TPP, [Co(tpp) ] , [Cu(tpp)] , [Zn(tpp)]
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and [FeCl(tpp) ] were purchased from Aldrich. Fullerenes C60 of 99.9 % purity and C70 of 98 % purity were used. Benzene and toluene were distilled over Na/benzophenone under argon ; trichloroethylene and CS2 were distilled over P2O5 under argon. The solvents were stored under argon. General : Single-crystal IR spectra were measured on a Perkin Elmer 1725X spectrophotometer, equipped with an IR microscope, in the 650 ± 3200 cmþ1 range. The powdered samples were pressed in KBr pellets (1:400) ; their spectra were recorded in the 400 ± 7000 cmþ1 range. Electronic absorption spectra were measured with a Perkin Elmer Lambda 19 UV-visible-NIR spectrophotometer in the 220 ± 3000 nm range (KBr pellet, 1:2000). Electronic reflectance spectra of the single crystals were recorded with a microspectroreflectometer equipped with an UV-visible microscope in the 240 ± 1150 nm range. The spectra were recorded in polarised light at room temperature. The absorption spectra were derived from the reflectance spectra by the Kramers ± Kronig transformation. Thermogravimetric analysis was carried out on a Q-1000 derivatograph in quartz bowls in the argon flow at the 10 ± 20 K minþ1 rate of heating in the 298 ± 1273 K range. The mass-loss temperature was determined from the minimum of DTG curve. X-ray photoelectron spectra (XPS) were measured with a VIEE-15 spectrometer upon excitation by MgKa radiation (E 1253.6 eV) and calibrated to the C 1s peak (285.0 eV). ESR spectra were registered with a Radiopan SE/X 2547 spectrometer. The conductivity was measured by two-contact method on pressed pellets. Synthesis : All complexes were obtained by the evaporation of equimolar solutions of C60 and corresponding porphyrin under argon during 5 ± 10 days. The analyses of the obtained complexes are summarised in Table 1. H2TPP ´ 2 C60 ´3 C6H6 (1) and H2TPP ´ 2 C60 ´4 C6H6 (2): Compounds 1 and 2 were obtained by crystallisation from the same benzene solution (at room temperature) as hexagonal needles and nonrectangular prisms, respectively. The crystals were washed with acetone until the disappearance of the H2TPP colour and dried in air. The relative yields 1 and 2 depend on the evaporation temperature ; 1 is predominantly formed below 15 8C and 2 above 24 8C. The crystals of 1 slowly deteriorate on storage in air or in argon due to the loss of the solvent. H2TPP ´ C70 ´2 C6H6 (3): Compound 3 precipitated from the benzene solution (at room temperature) as plates with quantitative yield. The crystals were washed with acetone and dried in air. They degrade on storage after several days. [Cu(tpp) ] ´ C60 ´C7H8 (7): Plate-like crystals of 7 were obtained from toluene in a quantitative yield. The crystals were washed with acetone and dried in air. They degrade on storage after several days. [Cu(tpp) ]2 ´C60 (8): Compound was obtained from a solution of C60 , CuTPP and ferrocene (1:1:10 molar ratio) in toluene as nonrectangular prismatic Table 5. Crystal data of 1, 2, 8 and 10. 1 formula Mr [g molþ1] crystal system space group a [] b [] c [] a [8] b [8 ] g [8 ] V [3] Z 1calcd [g cmþ3] m [mmþ1] T [K] Max. 2q [8] reflections measured unique reflections observed reflections [I b 2 s(I)] parameters R [I b 2 s ( I ) ] wR2
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2605 ± 2616
crystals in a quantitative yield. The solvent was decanted from the crystals before the precipitation of ferrocene, and the crystals were washed with acetone. [Cu(tpp) ] ´ C70 ´2 C7H8 (9): Compound 9 precipitated from toluene solution as prisms with a quantitative yield. The crystals were washed with acetone and dried in air. They degrade on storage after several days. [Mn(tpp)] ´ C70 ´ 1.25 CS2 (4), [Co(tpp) ] ´ C60 ´ 0.5 CS2 (5) and [Co(tpp)] ´ C70 (6): Compounds 4 ± 6 were obtained from CS2 as elongated parallelepipedal crystals, washed with diethyl ether until complete decoloration of the solution and dried under argon ; yields 50 ± 80 % (on fullerene). Black platelike crystals of a C60 ´ C70 ´ xCS2 solvate were obtained as a by-product and separated manually from the crystals of the molecular complexes under a microscope. The crystals of 4 are air sensitive and were handled in argon atmosphere. [Cu(tpp) ] ´ C70 ´ 1.5 C7H8 ´ 0.5 C2HCl3 (10), [Zn(tpp)(C5H5N)]2 ´C60 (11) and [FeCl(tpp)]2 ´C60 (12): Compounds 10 and 11 were obtained from trichloroethylene, with the addition of several drops of toluene and pyridine, respectively. Without these additional solvents, crystallisation does not occur. Compound 12 was crystallised from pure trichloroethylene. The crystals of parallelepipedal habit were washed with acetone and dried in air ; yield 90 %. A peculiar blue lustre is characteristic for all the complexes. Crystal structure determination : X-ray diffraction experiments for 1, 2, 8 and 10 were carried out on SMART 3-circle diffractometers with 1 K CCD area detectors in the Chemistry Department, University of Durham (1, 2) and in the Centre for X-ray Structural Studies, Institute of Organoelement Compounds R.A.S. (8, 10), by using graphite-monochromated MoKa radiation (l 0.71073 ). The data collection nominally covered over a half (for 1, 2, 8) or 34 (for 10) of the reciprocal space, by a combination of four sets of w scans, each set with different f and/or 2q angles. The absence of the crystal decay was monitored by repeating the first 50 scans at the end of the data collection and comparing the duplicate reflections. Reflection intensities were integrated using SAINT program.[43] The solution and refinement of all structures were performed with SHELXTL program package.[44] The intensity statistics were biased owing to strong anisotropic extinction that hindered the routine crystal structure determination by direct methods. The structures of 1, 2, and 10 were solved after omitting a group of reflections with the greatest normalized structure amplitudes in the primary set, and 8 after lowering the symmetry from the space group C2/c (later confirmed by the successful refinement) to C2. After this, all non-hydrogen atoms except some disordered ones of the fullerene skeleton or the solvent molecules, were revealed from E-syntheses, and the remaining atoms were located from the subsequent Fourier maps. The structures were refined by full-matrix least-squares against F 2 of all data.

2
6

8
6

10
60

H2TPP ´ 2C60 ´ 3C6H 2290.12 rhombohedral R (No. 148) 19.9967(8) 19.9967(8) 19.9967(8) 99.311(2) 99.311(2) 99.311(2) 7640 3 1.493 0.09 120 52.7 51 574 10 400 5579 839 0.119 0.366

H2TPP ´ 2C60 ´ 4C6H 2368.02 monoclinic P21/c (No. 14) 13.7422(6) 20.765(1) 18.626(1) 90 91.814(4) 90 5312 2 1.481 0.09 120 60.8 66 978 14 719 10 488 1191 0.062 0.147

[Cu(tpp) ]2 ´ C 2073.16 monoclinic C2/c (No.15) 22.6284(7) 20.5604(7) 19.6828(6) 90 106.145(1) 90 8796 4 1.565 0.56 110 60.1 40 445 12 881 8739 706 0.058 0.165

[Cu(tpp) ] ´ C70 ´ 1.5 C7H8 ´ 0.5 C2HCl 1582.67 triclinic å P1 (No. 2) 14.3756(6) 16.5497(8) 17.659(9) 72.460(1) 86.278(1) 80.577(1) 3951 2 1.305 0.37 110 60.1 43 877 22 654 14 023 1174 0.100 0.331

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The ordered non-hydrogen atoms were refined in anisotropic approximation, the disordered ones in isotropic approximation, with hydrogen atoms (partially revealed in difference Fourier maps) ªridingº in idealised positions. Crystal data and experimental parameters are listed in Table 5. Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-143510 (10), 143511 (8), 143512 (2) and 143513 (1). Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax : ( 44) 1223-336-033 ; e-mail : deposit@ccdc.cam.ac.uk).

R. N. Lyubovskaya et al.
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Acknowledgements
The work was supported by the Russian Program ªFullerenes and Atomic Clustersº and by Russian Foundation for Basic Research, grants Nos. 9903-32810 and 00-03-32577a. A support from the University of Durham (ISN, July ± October 1998) and the EPSRC funding of the Senior Research Fellowship (J.A.K.H.) are gratefully acknowledged. The authors (I.S.N. and Y.L.S.) are indebted to Prof. Mikhail Yu. Antipin for an access to the equipment and the software of the Centre for X-ray studies, Institute of Organoelement Compounds R.A.S.

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