Ligand Properties of Tri(2-thienyl)- and Tri(2-furyl)phosphine and -arsine (2-C4H3E)3P/As (E = O, S) in Gold(I) Complexes

Abstract

Tri(2-thienyl)- and tri(2-furyl)phosphine and -arsine (L) have been introduced as ligands to gold(I) chloride and acetate (AuX). Structural studies have shown that in the 1:1 complexes of the type L-Au-X the gold atoms are bound exclusively to the phosphorus/arsenic centers without any intraor intermolecular approach of the donor atoms of the three heterocycles towards the metal atoms. Intermolecular aurophilic bonding is found in the crystals of the [tri(thienyl)phosphine]gold acetate complex, but is absent in crystals of the chloride complexes. The phosphines L have been quaternized with methyl iodide and the resulting phosphonium salts [LMe]I structurally characterized to provide reference data as to the preferred configurational and conformational motifs. The mass spectra of the gold complexes indicate a high stability of the dinuclear cationic species [(LAu)2X]+ with X = Cl, OAc for all ligands L.