Tantalum complexes isocyanide

Although monodentate isocyanide-tantalum complexes are available by alternative routes,204 the majority of studies are concerned with the resultant 2-imines. Conversely, similar reactions with nitriles give monodentate imine moieties, which can undergo reactions while remaining attached to the metal.195,203-209... 

Tantalum complexes 38 were prepared through the reaction in Equation (22). The authors postulate coordination of one isocyanide to the boron with concomitant loss of methane, azaallyl formation, and finally coordination of the second isocyanide to boron followed by its insertion into the B-C bond <2002OM2422>. 

Interestingly, co-ordination of isocyanide ligand to the endo-hydride olefin tantalum complexes gives adducts containing organic groups [equation (6)]. ... 

The reaction of [p-MeC6H4C(NSiMe3)2]2Ta( = CH2)CH3 with 2,6-dimethyl-phenyl isocyanide afforded an f/ -ketenimine complex (Scheme 118). Carbon-sulfur cleavage reactions produced tantalum thioformaldehyde and tantalum sulfido complexes. ... 

No homoleptic isocyanide complexes of niobium, tantalum, titanium, zirconium, and halfnium have yet been synthesized. The vanadium cation... 

A mononuclear tantalum-benzyne complex (121) has been prepared by thermolysis of 120 [Eq. (20)].14 An X-ray crystal structure was reported for 121. Bond lengths for the benzyne unit are given in Table III. Complex 121 exhibits a rich insertion chemistry similar to that of Ti, Zr, and Ru benzyne complexes. Insertion reactions of 121 with ethylene, 2-butyne, acetonitrile, and carbon dioxide give 122, 123, 124, and 125, respectively (Scheme 15). Diphenylacetylene does not couple with 121, presumably because of steric constraints. Reagents with acidic protons such as methanol or terminal alkynes cleave the Ta—C bond to give butyl isocyanide and carbon monoxide, but... 

Niobium and tantalum halides also react with isocyanides to give migration products [equation (12.51)]. Azide complexes react with CNR to afford coordination compounds with tetrazolyl [equation (12.52)]. Codimerization and cooligomerization of... 

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