Perylene derivative charge transfer salts: synthesis, crystal structure and characterisation of (pet)3[Ni(mnt)2]2

Abstract

(pet)₃ [Ni(mnt)₂ ]₂ single crystals, where pet=perilo[1,12-b,c,d]thiophene and mnt= maleonitriledithiolate (cis-2,3-dimercapto-butene-2,3-dinitrile), were obtained by electrocrystallisation from dichloromethane solutions of pet and the tetrabutylammonium salt of [Ni(mnt)₂ ]^– . The crystal structure is triclinic, space group P1, with cell parameters a=10.2972(9), b=11.5037(12), c=13.3297(10) Å, alpha;=78.320(8) °, beta;=87.096(7) °, gamma;=87.785(8) °, Z=1 and consists of segregated stacks along a of partially oxidised pet molecules arranged as trimers, (pet)₃²⁺ , and dimerised [Ni(mnt)₂ ]^– anions. The electrical properties are typical of a semiconductor with room-temperature conductivity of ca. 9 S cm^–1 with an activation energy of 168 meV, and the paramagnetic susceptibility is due to a singlet–triplet type contribution of antiferromagnetically coupled pairs of S=1/2 spins of the [Ni(mnt)₂ ]^– species with J/k_B=–226 K.