NICKEL(IV) BIS((3)-1,2-DICARBOLLIDE) AS AN ACCEPTOR MOLECULE IN THE SYNTHESIS OF ELECTRICALLY CONDUCTING CHARGE-TRANSFER COMPLEXES

The reaction of {closo-(3)-1,2-C2B9H11}Ni-2(IV) (1) with tetrathiotetracene (TTT) and tetraselenotetracene (TSeT) leads to novel electrically conducting charge transfer complexes. The ESR and magnetic susceptibility of the complexes [TTT2](.+)[{closo-(3)-1,2-C2B9H11}Ni-2(III)](.-) (2) and [TSeT](.+)[{closo-(3)-1,2-C2B9H11}Ni-2(III)](.-) (3) were studied. The susceptibilities of both complexes exhibit approximately Curie-Weiss behavior. Complex 2 shows a slight deviation from the Curie-Weiss law in the temperature region where the crystals show a significant electrical conductivity. An electron transfer mechanism exists between the TTT radical cations and the [{closo-(3)-1,2-C2B9H11}Ni-2(III)](.-) anions, which is slowed with decreasing temperature. The single-crystal room-temperature electrical conductivities of 2 and 3 are 23.3 and 17.3 S.cm(-1), respectively. Single-crystal X-ray structures of 2 and 3 are reported and consist of segregated stacks of conducting TTT or TSeT cations and nickel dicarbollide anions. Crystal data for 2: C40H38B18NiS8 + C6H3Cl3, triclinic, P $($) over bar$$ 1, a = 6.834(1) Angstrom, b = 12.368(1) Angstrom, c = 16.077(2) Angstrom, alpha = 86.75(1)degrees, beta = 101.54(1)degrees, gamma = 102.54(1)degrees, V = 1299.5(5) Angstrom(3), Z = 1, D(calcd) = 1,546 g.cm(-3), T = 295 K, lambda = 0.7107 Angstrom, crystal size 0.50 x 0.32 x 0.05 mm, and mu = 8.76 cm(-1). Of the 4252 reflections measured, in the range 6 degrees < 2 theta > 48 degrees, 2937 were considered observed (I > 3 sigma(I)). The final R factor was R = 0.038, R(w) = 0.043. Crystal data for 3: C22H30B18NiSe4, triclinic, P $($) over bar$$ 1, a = 7.010 (1) Angstrom, b = 14.567 (1) Angstrom, c = 15.589 (3) Angstrom, alpha = 94.60 (1)degrees, beta = 89.92(2)degrees, gamma = 99.03 (2)degrees, V = 1567.0(8) Angstrom(3), Z = 1, D(calcd) = 1.830 g.cm(-3), T = 295 K, lambda = 1.5418 Angstrom, crystal size 0.50 x 0.11 x 0.01 mm, and mu = 64.85 cm(-1). Of the 5812 reflections measured, in the range 6 degrees < 2 theta > 134 degrees, 4689 were considered observed (I > 3 sigma(I)). The final R factor was R = 0.071, R(w) = 0.074.