Vicinal Dinitridoruthenium-Substituted Polyoxometalates γ-[XW10O38{RuN}2]6- (X = Si or Ge)

Reaction of the divacant polyoxometalate K8[gamma-XW10O36] (X = Si, Ge) with two equivalents of the metal-nitrido precursor Cs-2[(RuNCl5)-N-VI]. at room temperature in water. produces K-2(Me2NH2)(2)H-2[gamma-XW10O38-{RuN}(2)], X=Si (DMA-1a) or Ge (DMA-1b). The X-ray crystal structures of both complexes show monomeric complexes with highly unusual vicinal terminal metal-nitrido units. The Ru=N bond lengths are 1 594(10) and 1.612(11) angstrom in 1a and 1b, respectively EXAFS studies confirmed the key structural assignments front X-ray crystallography The XANES spectrum of DMA-1a. diamagnetism, NMR (Si-29 and W-183) chemical shifts. voltammetric behavior. reductive titrations with [PW12O40](4)(-) and computational data are all consistent with d(2) Ru-VI centers in these complexes. The FT-IR and Raman spectra show the expected vibrational modes of the {gamma-XW10) unit and the Ru N stictch at 1080 cm(-1). respectively. Interestingly, reduction of DMA-1a by 4 equivalents of [PW12O40](4)(-) produces NH3 in nearly quantitative yield Cyclic voltammetry versus pH and calculations provide the energetics for the possible two-electron reduction and two-proton addition processes in this reaction.