Design, crystal structures and magnetic properties of anionic salts containing fullerene C_(60) and indium(III) bromide phthalocyanine radical anions

摘要

Two salts containing fullerene C_(60) and indium(III) bromide phthalocyanine (Pc) radical anions have been obtained as single crystals: (TBA~+)_3(C_(60)~(?-)){In~(III)(Br)(Pc)~(?-)}(Br~-)·C_6H_4Cl_2 (1) and (TEA~+)_2(C_(60)~(?-)){In~(III)(Br)-(Pc)~(?-)}·C_6H_4C_(l2)·C_6H_(14) (2) where TBA~+ and TEA~+ are tetrabutyl- and tetraethylammonium cations, respectively. The presence of both radical anions is supported by spectra of 1 and 2 in the NIR and IR-ranges. The salts contain zigzag C_(60)~(?-) chains with 10.136 and 10.383 ? center-to-center (ctc) distances in 1 and a uniform ctc distance of 10.186 ? in 2. In 1, the C_(60)~(?-) radical anions are dimerized in the 180-140 K range to form singly bonded (C_(60)~-)_2 dimers, whereas they remain monomeric in 2. Effective packing of planar In (Br)(Pc)?- and spherical C_(60)~(?-) is attained by introducing fullerene spheres between the phenylene substituents of Pc allowing the formation of multiple van der Waals contacts between them. The effective magnetic moment of 1 at 300 K is 2.35μB, indicating a contribution of both C_(60)~(?-) and In(Br)(Pc)~(?-) species having S = 1/2 spin state. There is strong antiferromagnetic coupling of spins between fullerenes in the chains and fullerenes and phthalocyanines in the monomeric phase of 1 with the Weiss temperature of -120 K in the 300-180 K range. The formation of diamagnetic (C_(60)~-)_2 dimers switches off magnetic coupling and magnetically isolates In(Br)(Pc)~(?-) (Weiss temperature is only -1 K in the 140-10 K range). Magnetic behavior of 2 is described by the Curie-Weiss law with weak ferromagnetic coupling of spins with Θ = +7.6 K in the 50-300 K range. Both salts manifest single Lorentzian EPR lines at room temperature with g = 1.9911 and a linewidth (ΔH) of 25.4 mT (1) and g = 1.9956 and ΔH = 7.5 mT (2) which can be attributed to both C_(60)~(?-) and In(Br)(Pc)~(?-) species having strong exchange interaction. An asymmetric signal with the main component at g = 1.989-1.965 in the dimeric phase of 1 was attributed to the In(Br)(Pc)~(?-) radical anions.