Reactivity of tungsten(V) mononuclear complexes towards Li(TCNQ) and TCNQ. Comparison of the crystal structures of [W(S2CNMe2)4][TCNQ] and [Mo(S2CNMe2)4][TCNQ]·MeCN (TCNQ = 7,7,8,8-tetracyanoquinodimethane)‡

Abstract

The reaction of tungsten(V) complexes [W(S₂CNR₂)₄]I (R = Me or Et) with Li(TCNQ) in a dimethylformamide–water mixture at room temperature afforded the new derivatives [W(S₂CNR₂)₄][TCNQ] 1a and 1b (TCNQ = 7,7,8,8-tetracyanoquinodimethane). These compounds reacted further with TCNQ in acetonitrile to produce [W(S₂CNR₂)₄][TCNQ]₂ in which the TCNQ moieties are in a mixed-valence state. The physical properties of these new derivatives in solution and in the solid state are presented. The structures of 1a and of its molybdenum analogue [Mo(S₂CNR₂)₄][TCNQ]·MeCN 2a have been studied by X-ray diffraction analyses: in 1a the TCNQ moieties form alternating stacks along the c axis according to a quite unusual bond–bond overlap; in 2a the TCNQ^˙– moieties are dimerized and exhibit the usual slipped conformation.