Synthesis and Reactions of Polynuclear Polyhydrido Rare Earth Metal Complexes Containing “(C5Me4SiMe3)LnH2” Units: A New Frontier in Rare Earth Metal Hydride Chemistry

Abstract A series of tetranuclear octahydrido rare earth metal complexes of general formula (C 5 Me 4 SiMe 3 )Ln(μ‐H) 2 4 (THF) n (Ln = Sc, Y, Gd, Dy, Ho, Er, Tm, Lu; n = 0, 1, or 2) that contain C 5 Me 4 SiMe 3 as an ancillary ligand have been prepared and structurally characterized. These hydride clusters are soluble in common organic solvents such as THF, toluene, and hexane, and maintain their tetranuclear framework in solution. Such polynuclear polyhydrido complexes exhibit extremely high and unique reactivity toward a variety of unsaturated substrates including CO, CO 2 , and nitriles. The reaction of these neutral polyhydrides with one equivalent of Ph 3 CB(C 6 F 5 ) 4 affords the corresponding cationic hydride clusters (C 5 Me 4 SiMe 3 ) 4 Ln 4 H 7 (THF) n B(C 6 F 5 ) 4 , which can act as catalysts for the syndiospecific polymerization of styrene and regio‐ and stereospecific cis ‐1,4‐polymerization of 1,3‐cyclohexadiene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)