Coordination of CB11H12 to Cationic Zirconium(IV) Complexes. Synthesis and Structures of (C5H5)2Zr(η2-CH2Ph)(CB11H12), (C5H4Me)2Zr(CH3)(CB11H12), and (C5Me5)Zr(CH3)2(CB11H12)

Abstract

The reaction of Ag[CB11H12] with Cp2Zr(CH2Ph)2 yields (Cp2Zr(η2-CH2Ph)(η1-CB11H12) (1), in which the carborane coordinates to Zr via a single B-H-Zr bridge involving the B-H bond trans to the carbon of the closo CB11H12 anion. Data for 1: a = 9.802(5) Å, b = 13.663(5) Å, c = 10.860(4) Å, β = 92.48(4)°, V = 1453(2) Å3, Z = 2, in space group P21/m. A similar structure is observed for Cp′2Zr(CH3)(η1-CB11H12) (2, Cp′ = C5H4Me), which is prepared by reaction of Cp′2Zr(CH3)2 with Ag[CB11H12]. Data for 2: a = 13.504(2) Å, b = 19.432(3) Å, c = 7.919(1) Å, V = 2078(1) Å3, Z = 4, in space group Pnn2. The reaction of Cp*Zr(CH3)3 (Cp* = C5Me5) with Ag[CB11H12] yields Cp*Zr(CH3)2(η3-CB11H12) (3), in which the carborane coordinates in a unique tridentate fashion via three B-H-Zr bridges involving the B-H bonds on a triangular face opposite the carborane carbon. Data for 3: a = 12.360(3) Å, b = 19.450(4) Å, c = 9.161(2) Å, β = 90.93(4)°, V = 2202(1) Å3, Z = 4, in space group P21/c. Complex 1 polymerizes ethylene, and 2 oligomerizes propene under mild conditions, while 3 is unreactive with propene, 2-butyne, or styrene, apparently due to the lower lability of the tridentate carborane ligand. The CB11H12-ligands of 1–3 are rapidly displaced by CH3CN or THF. © 1993, American Chemical Society. All rights reserved.