Preparation and structural characterisation of isocyanide gold(I) nitrates, [Au(NO3)(CNR)] (R = Et, But or C6H3Me2-2,6); new auriophilic motifs †

Abstract

The first examples of isocyanide gold(I) nitrates, [Au(NO3)(CNR)] (R = Et, But or C6H3Me2-2,6) have been prepared from the corresponding chlorides and AgNO3. Full characterisation included crystal structure determinations for each example. The structures of the analogous compounds [AuCl(CNR)] (R = Et or C6H3Me2-2,6) were also determined for comparison. All species show Au· · ·Au interactions in the solid state, but with different modes of aggregation; [AuCl(CNEt)] and [Au(NO3)(CNBut)] have infinite zigzag chains, [AuCl(CNC6H3Me2-2,6)] has a ‘broken’ chain of tetrameric units, [Au(NO3)(CNEt)] has a linked chain of tetrameric units, while [Au(NO3)(CNC6H3Me2-2,6)] has a highly compressed chain. In each instance the Au· · ·Au interactions for [Au(NO3)(CNR)] are shorter than for the analogous [AuCl(CNR)], suggesting NO3– enhances these secondary bonds. This is in direct contrast to previous theoretical predictions. The structure of the solvated ionic compound [Au(CNC6H3Me2-2,6)2]NO3 has also been determined.