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

Reaction of the divacant polyoxometalate K₈[γ‐XW₁₀O₃₆] (X=Si, Ge) with two equivalents of the metal‐nitrido precursor Cs₂[Ru^VINCl₅], at room temperature in water, produces K₂(Me₂NH₂)₂H₂[γ‐XW₁₀O₃₈{RuN}₂], X=Si ( DMA ‐ 1 a ) or Ge ( DMA ‐ 1 b ). 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) Å in 1 a and 1 b , respectively. EXAFS studies confirmed the key structural assignments from X‐ray crystallography. The XANES spectrum of DMA‐1 a , diamagnetism, NMR (²⁹Si and ¹⁸³W) chemical shifts, voltammetric behavior, reductive titrations with [PW₁₂O₄₀]^4?, and computational data are all consistent with d² Ru^VI centers in these complexes. The FT‐IR and Raman spectra show the expected vibrational modes of the {γ‐XW₁₀} unit and the Ru?N stretch at 1080 cm^?1, respectively. Interestingly, reduction of DMA‐1 a 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.