Formation of the alkoxyalkyl complexes [M{CHMe(OMe)}(CO)<sub>2</sub>(η-C<sub>5</sub>H<sub>4</sub>R)](M = Mo, R = H; M = W, R = H or Me) and their transformations by loss of MeOH into η<sup>3</sup>-propenoyl or vinyl complexes. Crystal structures of [Mo{CHMe(PPh<sub>3</sub>)}(CO)<sub>2</sub>(PPh<sub>3</sub>)(η-C<sub>5</sub>H<sub>5</sub>)]BF<sub>4</sub>, [Mo(η<sup>3</sup>-CH<sub>2</sub>CHCO)(CO)(PPh<sub>3</sub>)(η-C<sub>5</sub>H<sub>5</sub>)] and [W(σ-CHCH<sub>2</sub>)(CO)<sub>2</sub>(PPh<sub>3</sub>)(η-C<sub>5</sub>H<sub>4</sub>Me)]
                                
                                    
                                        作者:Harry Adams、Neil A. Bailey、J. Trevor Gauntlett、Ian M. Harkin、Mark J. Winter、Simon Woodward                                    
                                    
                                        DOI:10.1039/dt9910001117
                                    
                                    
                                        日期:——
                                    
                                    Addition of MeSO3F or [Me3O]BF4 followed by PPh3 to the aldehyde complex [Mo(MeCHO)(CO)2(eta-C5H5)]- results in formation of the methoxyalkyl complex trans-[MoCHMe(OMe)}(CO)2(PPh3)(eta-C5H5)] in a reaction that proceeds via the unstable [Moeta-2-CHMe(OMe)}(CO)2(eta-C5H5)].  A by-product of this reaction is the ylide trans-[MoCHMe(PPh3)}(CO)2(PPh3)(eta-C5H5)]X (X = BF4- or SO3F-), a species (X = BF4) better prepared by treatment of trans-[MoCHMe(OMe)}(CO)2(PPh3)(eta-C5H5)] with HBF4 in the presence of PPh3.  The crystalline ylide trans-[MoCHMe(PPh3)}(CO)2(PPh3)(eta-C5H5)]BF4 is monoclinic, with a = 11.378(34), b = 18.903(35), c = 20.17(8) angstrom, beta = 115.28(31)-degrees and for the 3918 independent reflections with I/sigma(I) > 3.0, R = 0.0510.  In solution, trans-[MoCHMe(OMe)}(CO)2(PPh3)(eta-C5H5)] either degrades to [MoH(CO)2(PPh3)(eta-C5H5)] or loses MeOH to form the eta-3-propenoyl [Mo(eta-3-CH2CHC = O)(CO)(PPh3)(eta-C5H5)].  This molecule is monoclinic, with a = 17.231(50), b = 8.189(14), c = 16.727(36) angstrom, beta = 106.79(22)-degrees and for the 1654 independent reflections for which \F\/sigma(\F\) > 4.0, R = 0.100.  The proposed mechanism for its formation is based on isotopic tracking experiments and includes a vinyl to carbonyl migration.  Treatment of [WMe(CO)3(eta-C5H4R)] (R = H or Me) with PPh3 in MeCN gives the acyl [W(sigma-COMe)(CO)2(PPh3)(eta-C5H4R)].  These react with [Me3O][BF4] to form the cationic carbenes [W = CMe(OMe)}(CO)2(PPh3)(eta-C5H4R)]BF4, which in turn react with LiBHEt3 to give the alkoxyalkyls trans-[WCHMe(OMe)}(CO)2(PPh3)(eta-C5H4R)].  The alkoxyalkyls trans-[WCHMe(OMe)}(CO)2(PPh3)(eta-C5H4R)] react with traces of acid to form the sigma-vinyls trans-[W(sigma-CH = CH2)(CO)2(PPh3)(eta-C5H4R)], the methylcyclopentadienyl species of which is crystalline, monoclinic, with a = 36.952(40), b = 10.971(13), c = 25.148(23) angstrom and beta = 103.60(8)-degrees.  For the 2542 independent reflections for which \F\/sigma(\F\) > 5.0, R converged to 0.0750.