The equilibrium[Formula: see text]was studied in nitrobenzene solution and evidence for the occurrence of tricoordinate (Ph3P)2AuX was obtained. The results indicate that π-bonding of phosphine to gold(I) is much stronger than that of phosphine to silver(I). Attempts to prepare tricoordinate complexes from di(tertiary)phosphine or arsine failed. Chloro- and bromo(triphenylstibine)gold(I) have been prepared. The dipole moments of Ph3-MAuX, where M = P or As, and X = Cl, Br, and I, or M = Sb and X = Br have been determined. Metal–ligand stretching frequencies are compared.