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-P t Bu2)­(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-P t Bu2)­(CO)4] and involving the new complexes [W2Cp2(μ-P t Bu2)­(CO)4]­(BF4), [W2Cp2(μ-P t Bu2)­(CO)2(NO)2]­(BAr4), and [W2(μ-κ:η5-C5H4)­Cp­(μ-P t Bu2)­(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-P t Bu2)­(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 Bu2)­(CN t Bu)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-OP t Bu2)­(NO)]­(BAr4), likely resulting from a N–O bond cleavage step following decarbonylation.