Chemistry of a Nitrosyl Ligand κ:η-Bridging a Ditungsten Center: Rearrangement and N–O Bond Cleavage Reactions

[Image: see text] The novel nitrosyl-bridged complex [W(2)Cp(2)(μ-P(t)Bu(2))(μ-κ:η-NO)(CO)(NO)](BAr(4)) [Ar = 3,5-C(6)H(3)(CF(3))(2)] was prepared in a multistep procedure starting from the hydride [W(2)Cp(2)(μ-H)(μ-P(t)Bu(2))(CO)(4)] and involving the new complexes [W(2)Cp(2)(μ-P(t)Bu(2))(CO)(4)](BF(4)), [W(2)Cp(2)(μ-P(t)Bu(2))(CO)(2)(NO)(2)](BAr(4)), and [W(2)(μ-κ:η(5)-C(5)H(4))Cp(μ-P(t)Bu(2))(CO)(NO)(2)] as intermediates, which follow from reactions with HBF(4)·OEt(2), NO, and Me(3)NO·2H(2)O, respectively. The nitrosyl-bridged cation easily added chloride upon reaction with [N(PPh(3))(2)]Cl, with concomitant NO rearrangement into the terminal coordination mode, to give [W(2)ClCp(2)(μ-P(t)Bu(2))(CO)(NO)(2)], and underwent N–O and W–W bond cleavages upon the addition of CN(t)Bu to give the mononuclear phosphinoimido complex [WCp(NP(t)Bu(2))(CN(t)Bu)(2)](BAr(4)). Another N–O bond cleavage was induced upon photochemical decarbonylation at 243 K, which gave the oxo- and phosphinito-bridged nitrido complex [W(2)Cp(2)(N)(μ-O)(μ-OP(t)Bu(2))(NO)](BAr(4)), likely resulting from a N–O bond cleavage step following decarbonylation.