851511-61-0Relevant articles and documents
Synthesis of molybdenum(VI) monoimido alkyl and alkylidene complexes
Pilyugina, Tatiana S.,Schrock, Richard R.,Hock, Adam S.,Mueller, Peter
, p. 1929 - 1937 (2005)
In this paper we report the synthesis of several new Mo(NR)Cl 4(THF) species (R = C6F5, 3,5-(CF 3)2C6H3, 1-adamantyl, CPh 3, and 2,6-i-Pr2C6H3) via the treatment of MoCl4(THF)2 with azides and their reactions with neopentyl reagents. Addition of Mo(NR)Cl4(THF) complexes in toluene to a cold solution of NpMgCl in ether gave Mo(NR)Np3Cl species (R = C6F5) 3,5-(CF3)2C 6H3) Ad, Ph3C, and 2,6-i-Pr2C 6H3 (Ar); Np = CH2-t-Bu) in poor (35%) to modest (51%) yields. Heating Mo(NAr)Np3Cl in C6D 6 to 50 °C results in α-hydrogen abstraction to give neopentane and a molecule whose NMR spectra are consistent with it being Mo(NAr)(CH-t-Bu)(CH2-t-Bu)Cl; it decomposed bimolecularly upon attempted isolation. The other Mo(NR)Np3Cl species were found to be more stable than Mo(NAr)Np3Cl, but when they did decompose at elevated temperatures, no neopentylidene complex could be observed. Addition of neopentyllithium to Mo(NR)Np3Cl species (R = Ar, CPh3, or Ad) yielded Mo(NR)(CH-t-Bu)Np2 species, the adamantylimido version of which is unstable toward bimolecular decomposition. Addition of neopentyllithium to Mo(NR)Np3Cl complexes in which R = pentafluorophenyl or 3,5-trifluoromethylphenyl led to intractable mixtures. Addition of 1 equiv of 2,6-diisopropylphenol, 2,6-dimethylphenol, or 3,5-(2,4,6-i-Pr3C6H2)2C 6H3OH (HIPTOH) to Mo(NCPh3)(CH-t-Bu)Np 2 led to formation of Mo(NCPh3)(CH-t-Bu)Np(OR) species, while treatment of Mo(NCPh3)(CH-t-Bu)2(CH 2-t-Bu) with C6F5OH gave Mo(NCPh 3)-Np3(OC6F5). The three monophenoxide neopentylidene complexes showed poor to moderate metathesis activity for ring-closing a small selection of substrates. X-ray studies were completed for Mo[N-3,5-(CF3)2C6H 3]Cl4(THF), Mo[N-3,5-(CF3)2C 6H3]Np3Cl, Mo(NCPh3)-Np 3Cl, and Mo(NCPh3)(CH-t-Bu)(CH2-t-Bu)(OHIPT).
