GOLD COMPLEXES WITH SELENIUM LIGANDS .7. SYNTHESIS AND CRYSTAL-STRUCTURES OF OLIGONULEAR GOLD(I)-SELENOLATE COMPLEXES

Cationic and neutral oligonuclear organophosphinegold(I) complexes with organic selenolate ligands SeR- [R = Ph, CH2Ph, C6H4NH2-4, C6H4CI-4 or C10H7 (naphthyl)] have been prepared and characterized by spectroscopic methods. Additionally, X-ray crystal structure analyses have been performed for [(AuPPh3)2(SeCH2Ph)]SbF6, the mixed cationic-neutral complex [(AuPPh3)2(SeC10H7)]SbF6.[Au(PPh3)-(SeC10H7)] and for [(AuSePh)2(dppe)] [dppe = 1,2-bis(diphenylphosphino)ethane]. The Au-Se bond lengths lie in the range 2.41 2 angstrom (neutral complexes) to 2.465 angstrom (cationic complexes). All crystal structures show distortions of the co-ordination geometry at selenium and reveal short Au ... Au contacts. The molecular structure of [(AuPPh3)2(SeCH2Ph)]SbF6 represents the first example of a cationic alkylselenolate-gold complex. The complex [(AuPPh3)2(SeC10H7)]SbF6.[Au(PPh3)(SeC10H7)] exhibits an unexpected structure: the cationic and the corresponding neutral selenolate complex are linked by intermolecular Au ... Au interactions, thus forming a trinuclear selenolate complex. The complex [(AuSePh)2(dppe)] is the first structurally characterized gold-organoselenolate complex with a bridging diphosphine ligand.