Preparation of Zirconium Guanidinate Complexes from the Direct Insertion of a Carbodiimine and Aminolysis Using a Guanidine. Comparison of the Reactions

Direct insertion of 1 equiv of CyNCNCy
(1; Cy = cyclohexyl) into the Zr–NMe2 bonds in (Me2N)3Zr­[N­(SiMe3)2] (2) and (Me2N)3Zr­[Si­(SiMe3)3] (3) gave exclusively [CyNC­(NMe2)­NCy]­Zr­(NMe2)2[N­(SiMe3)2] (5) and [CyNC­(NMe2)­NCy]­Zr­(NMe2)2[Si­(SiMe3)3] (6), respectively. The reaction
between 2 and guanidine CyNHC­(NMe2)NCy
(9) gave 5 and HNMe2 through
the preferred cleavage of a Zr–NMe2 bond in 2. The reaction between 3 and 9 led
to the preferred cleavage of the Zr–Si­(SiMe3)3 bond in 3, yielding [CyNC­(NMe2)­NCy]­Zr­(NMe2)3 (7) and HSi­(SiMe3)3 and, upon cleavage of another Zr–NMe2 bond,
forming [CyNC­(NMe2)­NCy]2Zr­(NMe2)2 (8). The aminolysis of Zr­(NMe2)4 (4) by 9 first afforded 7 and then 8. The structures of 5, 6, and 9 have been determined by X-ray diffraction.