Tetrathiafulvalene and Tetramethyltetraselenafulvalene Salts with [M(dcdmp)2] Anions (M = Au, Cu, and Ni): High Conductivity and Unusual Stoichiometries

Silva, R.A.L.; Santos, I.C.; Gama, V.; Lopes, E.B.; Auban-Senzier, P.; Almeida, M.; Belo, D.

Key information

Authors:

Silva, R.A.L. (Rafaela Antunes Leão da Silva); Santos, I.C. (Isabel Maria Fernandes Cordeiro dos Santos); Gama, V. (Vasco Pires Silva da Gama); Lopes, E.B. (Elsa Maria Simões Branco Lopes); Auban-Senzier, P.; Almeida, M. (Manuel José Duarte Leite de Almeida); Belo, D. (Maria Dulce Jesus Pombo Belo)

Published in

November 6, 2019

Abstract

Four new charge transfer salts based on tetrathiafulvalene (TTF) or tetramethyltetraselenafulvalene (TMTSF) donors and transition metal complexes [M(dcdmp)2] (dcdmp = 2,3-dicyano-5,6-dimercaptopyrazine), TMTSF5[Cu(dcdmp)2]4 (1), (TMTSF)2[Ni(dcdmp)2] (2), and (TTF)7[M(dcdmp)2]6 (M = Au (3) and Cu (4)) were prepared by electrocrystallization. These compounds are characterized by a rich variety of crystal structures with unusual donor/acceptor stoichiometries. In spite of the uncommon structural types observed, these salts can be highly conducting. Compound 1 crystallizes with segregated TMTSF stacks, showing 1D metallic properties with a room temperature conductivity of 134 S/cm. Compound 2 crystallizes in an out-of-registry mixed column arrangement of donor dimers and acceptors. Compounds 3 and 4 appear in single crystal X-ray diffraction as isostructural and composed of columns of TTF hexamers that are disrupted by a single TTF layer and surrounded by [M(dcdmp)2]− monoanionic pairs, aligning perpendicularly to the hexamer stacks. However, measurements of the electric transport properties in single crystals suggest the existence of two phases. While phase 2 has a semiconducting behavior, phase 1 is clearly more conductive with copper complex 4 presenting a metal semiconductor transition around 210 K and room temperature conductivity of ∼210 S/cm.