Synthesis and structures of titanium and yttrium complexes with N,N′-tetramethylguanidinate ligands: different reactivity of the M–N bonds toward phenyl isocyanate

Abstract

A salt elimination reaction of bis(cyclopentadienyl)titanium dichloride (C(5)H(5))(2)TiCl(2) with one equiv. of N,N'-tetramethylguanidinate lithium [LiN[double bond, length as m-dash]C(NMe(2))(2)] proceeded in THF at room temperature to yield a bis(cyclopentadienyl)titanium mono-guanidinate chloride (C(5)H(5))(2)TiCl(N[double bond, length as m-dash]C(NMe(2))(2)) (). However, treatment of two equiv. of LiN[double bond, length as m-dash]C(NMe(2))(2) with (C(5)H(5))(2)TiCl(2) under the same conditions resulted in the elimination of one cyclopentadienyl ring to form an unexpected mono(cyclopentadienyl)titanium bis(guanidinate) chloride (C(5)H(5))TiCl[N[double bond, length as m-dash]C(NMe(2))(2)](2) (), in which only one Ti-Cl bond is broken, with the other Ti-Cl bond retained. Reaction of [(C(5)H(5))(2)YCl](2) with LiN[double bond, length as m-dash]C(NMe(2))(2) gave the corresponding product {(C(5)H(5))(2)Y[mu-eta(1):eta(2)-N[double bond, length as m-dash]C(NMe(2))(2)]}(2) (). On further investigations on the reactivity of toward phenyl isocyanate, we found phenyl isocyanate only inserts into the Y-N(mu-Gua) bonds of to yield [(C(5)H(5))(2)Y(mu-eta(1):eta(2)-OC(N[double bond, length as m-dash]C(NMe(2))(2))NPh)](2) (). Complexes were characterized by elemental analysis and spectroscopic properties and their solid-state structures were determined by X-ray single-crystal diffraction.