Supramolecular chemistry of gold(I) thiocyanate complexes with thiophene, phosphine and isocyanide ligands, and the structure of 2,6-dimethylphenyl isocyanide

Abstract

The reaction of equivalent quantities of (L)AuCl (L = tetrahydrothiophene, trimethylphosphine, 2,6-xylyl isocyanide or mesityl isocyanide) and KSCN in CH2Cl2–water gave (L)Au(SCN) in excellent yield. The products were formed through Cl ↔ (SCN) anion exchange in the two-phase systems. Crystals of (THT)Au(SCN) contain short inter-ion Au⋯Au contacts (3.006 A) within chain polymers of alternating cations [Au(THT)2]+ and anions [(NCS)2Au]−. The crystal structure of (Me3P)Au(SCN) exhibits dimers based on short Au⋯Au contacts of 3.099 A. The dimers appear to aggregate further by long Au⋯S contacts giving a tetrameric motif. Molecules of (2,6-Me2C6H3NC)Au(SCN) crystallise as flat, centrosymmetric dimers with long intermolecular Au⋯Au and Au⋯S contacts. Although the general aurophilic motif of (2,4,6-Me3C6H2NC)Au(SCN) is similar to (2,6-Me3C6H3NC)Au(SCN), its structure has two different dimers formed from similar monomers. The crystal structure of 2,6-Me2C6H3NC was also characterised and (consistent with bonding theory of metal isocyanides) exhibited a CN bond which is slightly longer than in the gold(I) complex.