Bulky formamidinate complexes of lithium: the first examples of η2:η1-CN,N′ metal amidinate coordination

Abstract

The lithium complexes [Li{N(Ar)C(H)N(Ar)}(pmdeta)], where Ar = 2,6-R₂C₆H₃ (R = Me (1), Et (2) and ⁱPr (3)) and pmdeta = N,N,N′,N″,N″-pentamethyldiethylenetriamine, have been synthesised and their solid state structures determined by X-ray methods. Compounds 1–3 comprise a Li(pmdeta) centre coordinated by a bulky formamidinate in either the E-syn or E-anti isomeric form. The structures of compound 3 and one unique molecular unit of compound 1 (E-anti isomer) display coordination of the pendant amidinate imine, and can therefore be considered the first examples of η²:η¹-CN,N^′ metal amidinate coordination.