Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pri2C6H3)

The compounds [MoCl(NAr)2R] (R=CH2CMe2Ph (1) or CH2CMe3(2); Ar=2,6-Pri2C6H3) have been prepared from [MoCl2(NAr)2(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl2(NAr)(NBut)(dme)] affords [MoCl(NAr)(NBut)(CH2CMe2Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)2(CH2CMe2Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)2(CH2CMe2Ph)] (5) (Ind=Indenyl), [Mo(OBut)(NAr)2(CH2CMe 2Ph)] (6), [MoMe(NAr)2(CH2CMe2Ph)] (7), [MoMe(PMe3)(NAr)2(CH2CMe 2Ph)] (8) (formed in the presence of PMe3) and [Mo(NHAr)(NAr)2(CH2CMe2P h)](9). In the latter case, a by-product {[Mo(NAr)2(CH2CMe2Ph) ]2(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.