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

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.