Intermolecular Aurophilic versus Intramolecular Au⋅⋅⋅N Secondary Interactions in Two‐Coordinate Gold(I) Selenolate Complexes

Abstract

AbstractA series of gold(I) selenolates viz., [Au(Sepy‐2)(PPh3)] (1), [Au(Sepy‐4)(PPh3)] (2) (py=pyridyl), [Au(Sepyz‐2)(PPh3)] (3) (pyz=pyrazinyl), [Au(Sepym‐2)(PPh3)] (4) (pym=pyrimidyl) and [Au{Sepym(Me2‐4,6)‐2}(PPh3)] (5) {pym‐2‐(Me2‐4,6)=4,6‐dimethyl‐2‐pyrimidyl} have been synthesized and structurally characterized. The gold atom acquires a two‐coordinate linear geometry with Au−Se distance of ∼ 2.41 Å. The existence of aurophilic interactions are determined by the nature of substituent on selenium. It was observed that the complexes derived from selenolate ligand with pyridyl moiety (one hetero‐N atom in the ring) could exhibit aurophilicity; whereas, the complexes derived from ligands containing pyrazinyl and pyrimidyl moieties (two hetero‐N atoms) are devoid of such interaction but show secondary Au⋅⋅⋅N interaction. The complex [Au(Sepy‐4)(PPh3)] shows polymorphism and the two polymorphs differ in the relative orientations of linear molecules. There are competing secondary intramolecular Au⋅⋅⋅N interaction which plays crucial role on intermolecular aurophilic interaction and overall structure. Theoretical calculations at DFT and MP2 levels have been carried out to rationalize the experimental findings.