Stable Silver(I) Hydride Complexes Supported by Diselenophosphate Ligands

The first stable structure of silver(l) cluster cations [Ag-8(mu(4)-H){Se2P(OR)(2)}(6)](+) [R = Pr-i, 1; Et, 2] containing Ag(l)-hydride bridges (Ag-mu-H-Ag) in T symmetry was reported. The clusters having an interstitial hydride were composed of an octanuclear silver core in tetracapped tetrahedral geometry, which was inscribed within a Se-12 icosahedron represented by six dialkyl diselenophosphate ligands in a tetra metallic-tetraconnective (mu(2), mu(2)) bonding mode. The presence of hydride was unequivocally corroborated by both H-1 and Ag-109 NMR spectroscopies of which a nonet in the H-1 NMR spectrum for the hydride resonance coupled with a doublet peak observed in the Ag-109 NMR spectrum clearly suggests that eight silver nuclei are equivalent in the NMR time scale and a fast exchange of the positions between the vertex and capping silver atoms in solution must occur. The hypothesis was also supported by a density functional theory (DFT) investigation on a simplified model [Ag-8(H)(Se2PH2)(6)](+), which confirmed that the Ag8H cubic core of T-h symmetry may not be formed as it is energetically highly unfavorable (0.67 eV less stable than the T structure).