Novel silver diselenophosphate clusters: structures of Ag-10(mu(10) Se)[Se2P(OEt)(2)](8) and {Ag[Se2P(OPri)(2)]}(6)

Two types of clusters, [Ag(Se2P(OR)(2))](n) (R = Et, n = infinity, 1a; R = Pr-i, n = 6, 1b) and Ag-10(mu(10)-Se)[Se2P(OR)(2)](8) (2a, 2b) were obtained from the reaction of stoichiometric amounts of Ag(CH3CN)(4)PF6 and NH4Se2P(OR)(2) in (C2H5)(2)O at -20 degreesC. These new silver(I) clusters containing diselenophosphate (dsep) ligands were characterized by elemental analysis, NMR spectroscopy, fast-atom bombardment mass spectrometry (FAB-MS) for 2, and, in the case of 1b, and 2a, by X-ray crystallography. The structure of 1b reveals a hexameric aggregate {Ag[Se2P(OPri)2]} 6 where six silver atoms are located at the corners of a pseudohexagonal prism alternating with selenium atoms in two Ag3Se3 rings interconnected vertically by the P-Se bridges of the dsep ligands but not by additional Ag-Se bonding. The dsep ligands are organized in a paddle-wheel fashion about an Ag6Se6 pseudohexagonal prismatic core. The decasilver clusters 2 contain an encapsulated selenium atom in a distorted, cis-bicapped trapezoidal-prismatic geometry and are surrounded by eight dsep ligands having three different types of coordination pattern. Furthermore, the hypercoordinated selenide ion, Se2-, in 2 was unequivocally identified by the solution Se-77{H-1} NMR spectrum with a chemical shift centered at -1396 ppm.