An ion-pair complex [TTF] [Pd(mnt)_2]: synthesis, crystal structure, magnetic property, and electrical conductivity

摘要

A new ion-pair complex, [TTF][Pd(mnt)_2] (1), where TTF~+ = tetrathiafulvalene and mnr~(2-) = maleo-nitriledithiolate, was synthesized and characterized structurally. Compound 1 crystallizes in triclinic space group P-1, with a = 8.008(5)A, b= 11.333(8)A, c= 11.373(6)A, α= 108.112(7)°, β=91.550 (5)°, γ 95.232(5)°, and V=975.2(11)A~3. The [TTF]~+ cations (C) and [Pd(mnt)_2]~- anions (A) form mixed stacks in ...AACCAACC... fashion, and the neighboring mixed stacks are held together via van der Waals forces in the crystal. Compound 1 shows weak Curie/Weiss-type magnetic behavior from 2 to 370 K; theoretical investigation disclosed the existence of strongly antiferromagnetic coupling in both [Pd(mnt)_2]_2~(2-) and [TTF]_2~(2+) dimer pairs via frontier orbitals overlap mechanism and weakly ferromagnetic coupling between the face-to-face overlapped [TTF]~+ and [Pd(mnt)_2]~- via spin polarization mechanism within a mixed stack. The powdered pellet electrical conductivity measurement indicated that I shows semiconductor character with activation energy of l.l(3)eV.