769923-89-9Relevant academic research and scientific papers
Substituent effects. Synthesis and structural characterization of group 4 metallacarboranes containing (C6H5CH2) 2C2B9H92- and [o-C 6H4(CH2)2]C2B 9H92- ligands
Kwong, Wai-Chuen,Chan, Hoi-Shan,Tang, Yong,Xie, Zuowei
, p. 4301 - 4307 (2004)
Substituants on the carborane cage carbons affect not only bonding interactions between the group 4 metal ion and the carboranyl of the C 2B9 system but also the reactivity pattern of the resulting metal complexes. Treatment of MCI4(THF)2 with 1 equiv of [(C6H5CH2)2C 2B9H9]Na2(THF),x in THF at room temperature gave the bis(carboranyl) complexes {n4:n 2-[(C6H5CH2)2C 2B9H9]2MCI(THF)}{Na(THF) 3} (M = Zr (1), Hf (2)). Under the same reaction conditions, interaction of TiCl4(THF)2 with 1 equiv of [(C 6H5CH2)2C2B 9H9]Na2(THF)x led to the isolation of a small amount of TiCl3(THF)3 and B-substituted zwitterionic compound (C6H5CH2) 2C2B9H9(THF) (4). Reaction of 1 with 1 equiv of Li[N(SiMe3)2] resulted in the replacement of a Na+ by a Li+, giving the ionic complex [n 3:n2-{(C6H5CH2) 2C2B9H9}2ZrCl-(THF)] [Li(THF)4] (3). ClZr[N(SiMe3)2]3 was isolated from the reaction of 1 with excess Li-[N(SiMe3) 2]. An equimolar reaction between M(NEt2)4 and (C6H5CH2)2B9H 11 afforded the monocarboranyl complexes [n2-(C 6H5CH2)2C2B 9H9]M(NEt2)2(NHEt2) (M = Ti (5), Zr (6)). It is believed that the additional N(p π)→M(dπ) interactions stabilize this type of complex. Treatment of MCl4(THF)2 with 1 equiv of less bulky yet rigid [{o-C6H4(CH2) 2}C2B9H9]Na2-(THF) x generated a bent-metallocene type of complex, [{o-C 6H4(CH2)2}C2B 9H9]2M(THF)2 (M = Zr (7), Hf (8)). These metallacarboranes were all fully characterized by various spectroscopic techniques and elemental analyses. Molecular structures of 1 and 3-5 were confirmed by single-crystal X-ray analyses.
