Protonation reactions of dinitrogen complexes of molybdenum and tungsten with PMe3 as Co-ligand. X-Ray structure of the hydrazidium complex [WCl(NNH3)(PMe3)4] Cl2

Abstract

The reactions of cis-[M(N₂)₂(PMe₃)₄] or [M(N₂)(PMe₃)₅](M = Mo or W) with HX (X = Cl or l) give the hydrazido (2–) complexes [MX(NNH₂)(PMe₃)₄]X as intermediate products. For M = Mo, the final product is ammonia, but for M = W, X = Cl, the final product is the hydrazidium complex [WCl(NNH₃)(PMe₃)₄]Cl₂(A). These reactions have been monitored by ³¹P and ¹⁵N n.m.r. spectroscopy, and complex (A) has been structurally characterised by X-ray diffraction. It exists in the solid state as centrosymmetric dimer units consisting of two cations linked through Cl anions by strong hydrogen bonds. The W–N–N group is almost linear with W–N 1.785(15) and N–N 1.40(2)Å. Compound (A) can also be prepared from [WCl(NNH₂)(PMe₃)₄]Cl and HCl, but it is converted by Na[BPh₄] in methanol into the hydrazide complex [WCl(NNH₂)(PMe₃)₄][BPh₄].