Synthesis and characterization of dinuclear gold(I) ring and open-ring complexes containing saturated and unsaturated dithiol bridging ligands and phosphine or bis(diphosphine) donor ligands. Crystal structures of [Au2(.mu.-S(CH2)3S) (.mu.-dppm)], [Au2(.mu.-MNT)(PPh3)2], [Au2(.mu.-S2C6H4) (PPh3)2], and [Au4(.mu.-S2C6H3CH3)2(PEt3)2]