The design of ionic complexes of fullerenes manifesting magnetic transitions and high conductivity

The design of multicomponent ionic complexes of fullerenes, (D1) (C60 ) (D2) is discussed. In this approach D1 was an organic cation and D2 was a neutral structure-forming molecule. These complexes demonstrated paramagnetic-diamagnetic transitions associated with the C-C and M-C bond formation, singlet-triplet transitions and high conductivity. 1. (D) (C60 ) CoOEP contain tetramethylphosphonium (1) and N-methyldiazabicyclooctane (MDABCO (2)) cations. Diamagnetic -bonded {CoOEP (C60 )} anions in 1 do not dissociate up to 290K. In 2 both MDABCO and C60 coordinate to CoOEP and reversible dissociation of the Co-C(C60 ) -bond is observed at 50-250K. The dissociation is accompanied by transition from diamagnetic to paramagnetic state [1]. 2. Unusual (C60 )2 dimer bound by two bonds was found in {(MDABCO) CoTMPP}2 (C60 )2. The dimer has a biradical state (S = 1) at 300 K. The EPR behaviour of the dimer was described within the model for triplet excited (S = 1) and singlet ground states (S = 0) with the energy gap of 70 2 cm [2]. 3. Complexes of C60 and C70 anions with coordination (MDABCO)2 MTPP assemblies (M = Zn, Co, Mn, Fe) involve layers formed by (MDABCO)2 MTPP and zigzag chains of C60 . In the zigzag chains C60 spins are antiferromagnetically coupled. The 70 complexes contain diamagnetic (C70 )2 dimers linked by one bond [3]. 4. The (D) (C60 ) TPC complex manifests metallic behaviour. In the complex there are two types of closely packed hexagonal layers built of monomeric C60 anions. Different environment of C60 anions provides different rotation freedom. The effect of the rotation of C60 anions on metallic conductivity is discussed. 5. Complexes (D)2 (C60 )2 ET contain double chains formed by C60 and manifest reversible dimerization of C60 in the 250-280K range. The crystal structures of monomeric and dimeric phases and the changes of the magnetic properties of the complexes at the dimerization are discussed. The work was supported by the Russian Science Support Foundation, INTAS YSF 05-109-4653 and RFBR grants N 06-03-32824 and 06-03-91361.