Hydrogen bonding interactions in single component molecular conductors based on metal (Ni, Au) bis(dithiolene) complexes

Dalton Trans. 2020 May 14;49(18):6056-6064. doi: 10.1039/d0dt00960a. Epub 2020 Apr 22.

Abstract

Introduction of hydrogen bonding (HB) interactions in single component conductors derived from nickel and gold bis(dithiolene) complexes is explored with the 2-alkylthio-1,3-thiazole-4,5-dithiolate (RS-tzdt) with R = CH2CH2OH through the preparation of the neutral [Ni(HOEtS-tzdt)2]0 (closed-shell) and [Au(HOEtS-tzdt)2]˙ (radical) complexes. At variance with many other radical gold dithiolene complexes which have a strong tendency to dimerize in the solid state, [Au(HOEtS-tzdt)2]˙ crystallizes into uniform stacks interconnected by strong O-HN HB involving the nitrogen atom of the thiazole ring. [Au(HOEtS-tzdt)2]˙ is isostructural with its neutral, closed-shell nickel analog [Ni(HOEtS-tzdt)2]0, a rare situation in this metal bis(dithiolene) chemistry. It demonstrates how the strength of the HB directing motif can control the overall structural arrangement to stabilize the same structure despite a different electron count. The nickel complex behaves as a band semiconductor with weak room temperature conductivity (1.6 × 10-5 S cm-1), while the gold complex is described as a Mott insulator with a three orders of magnitude improved conductivity (6 × 10-2 S cm-1).