Isocyanide ligands insertion reactions with metal complexes

Since the vanadium center of vanadocenes is electron-deficient, various vanadium derivatives are formed by the attack with PR3, CO, or unsaturated jr-donating ligands. This reaction provides a useful synthetic method for the synthesis of ] -alkene complexes as described later. Thus formed Cp 2V(CO) (22) is converted to the cyano derivative (23, see Cyanide Complexes of the Transition Metal on treatment with the isocyanide (Scheme 12). ( -C5]V[e5)2V is incubated with O2 at —78°C to yield [(/U.- -C5]V[e503)V(0)]2 via oxygen insertion into the carbon-vanadium bond. ... 

Their formation can be rationalized in several ways. It may involve insertion of the isocyanide into the M—Et bond of an intermediate monoethyl complex, but it can also be explained by substitution of one of the chloro ligands in the starting material by the metalated aldimine, which results from the reaction of f-BuNC with EtMgCl. NMR data suggest a dynamic coordination behavior for the tethered ether ligand and also for the (imino)propionyl group, whose coordination mode may be either or... 

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