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

The novel nitrosyl-bridged
complex [W2Cp2(μ-PtBu2)(μ-κ:η-NO)(CO)(NO)](BAr4) [Ar = 3,5-C6H3(CF3)2] was prepared in a multistep procedure starting from the
hydride [W2Cp2(μ-H)(μ-PtBu2)(CO)4] and involving the
new complexes [W2Cp2(μ-PtBu2)(CO)4](BF4), [W2Cp2(μ-PtBu2)(CO)2(NO)2](BAr4), and [W2(μ-κ:η5-C5H4)Cp(μ-PtBu2)(CO)(NO)2] as intermediates,
which follow from reactions with HBF4·OEt2, NO, and Me3NO·2H2O, respectively. The
nitrosyl-bridged cation easily added chloride upon reaction with [N(PPh3)2]Cl, with concomitant NO rearrangement into the
terminal coordination mode, to give [W2ClCp2(μ-PtBu2)(CO)(NO)2], and underwent N–O and W–W bond cleavages
upon the addition of CNtBu to give the
mononuclear phosphinoimido complex [WCp(NPtBu2)(CNtBu)2](BAr4). Another N–O bond cleavage was induced upon photochemical
decarbonylation at 243 K, which gave the oxo- and phosphinito-bridged
nitrido complex [W2Cp2(N)(μ-O)(μ-OPtBu2)(NO)](BAr4), likely
resulting from a N–O bond cleavage step following decarbonylation.