Gold(I) Complexes Containing Phosphanyl‐ and Arsanylborane Ligands

The structural and photophysical properties of a series of new Au I compounds have been studied. The reactions of AuCl(tht) with the phosphanyl‐ and arsanylboranes RR ′ EBH 2 NMe 3 (E=P, As; R=H, Ph; R′=H, Ph, t Bu) afford the complexes [AuCl(RR ′ EBH 2 NMe 3 )]. In the solid state, [AuCl(H 2 PBH 2 NMe 3 )] 2 ( 2 a ) is a dimer showing unsupported intermolecular aurophilic interactions with short Au⋅⋅⋅Au distances. In contrast, [AuCl(H 2 AsBH 2 NMe 3 )] n ( 2 b ) aggregates to form 1D chains. Organic substituents on the pnictogen atoms lead to discrete molecules in [AuCl(RR ′ PBH 2 NMe 3 )] ( 2 c : R=H, R′= t Bu; 2 d : R=R′=Ph). To increase the aurophilicity, the ionic homoleptic complexes [Au(RR ′ EBH 2 NMe 3 ) 2 ][AlCl 4 ] ( 3 a – d ) have been synthesized, for which 3 a,b form chains in the solid state and exhibit luminescence. The emissions show a drastic redshift with temperature decrease, correlating with decreasing Au⋅⋅⋅Au distances. DFT calculations provide insight into the bonding situation of the products.