N-substituted guanidinate anions as ancillary ligands in group 4 chemistry. Syntheses and characterization of M{RNC[N(SiMe3)(2)]NR}(2)Cl-2, [M{CyNC[N(SiMe3)(2)]NCy}Cl-3](-) (M = zr, hf; R = Pr-i, cy), and Zr{CyNC[N(SiMe3)(2)]NCy}(CH2Ph)(3)

摘要

Addition of N(SiMe3)(2) anion equivalents to carbodiimides, RN=C=NR (R = cyclohexyl, isopropyl), generated tetrasubstituted guanidinates which provided entry to a series of bis- and mono(guanidinate) complexes of Zr and Hf exhibiting the general formulas {RNC[N(SiMe3)(2)]NR}(2)MCl2 (R = isopropyl, M = Zr (1), Hf (2); R = cyclohexyl, M = Zr (3), Hf (4) and {CyNC[N(SiMe3)(2)]NCy}MeL4](-) (M = Zr (5), Hf (6)) depending on the metal:ligand ratio used in the reaction. In addition to spectroscopic characterization, definitive evidence for the molecular structures of these products is provided through single-crystal X-ray analyses for 1, 3, 4, 5, and 6, which are presented. These results further define the ligand-bonding parameters and provide clear evidence that the planar N(SiMe3)(2) functional groups and the MNCN planes have a nearly perpendicular orientation and therefore do not experience significant pi overlap. Complex 5 provides an access to the organometallic derivative {CyNC[N(SiMe3)(2)]NCy}Zr(CH2Ph)(3) (7) by reaction with 3 equiv of PhCH2MgCl. Single-crystal X-ray analysis confirmed the connectivity of this species and indicated an eta(2)-benzyl group. These results provide the first reported example of an organozirconium complex supported by a guanidinate Ligand. [References: 38]