906562-19-4Relevant academic research and scientific papers
Alkylyttrium complexes supported by N,N′-dicyclohexyl-N″- bis(trimethylsilyl)guanidinate ligands
Trifonov, Alexander A.,Lyubov, Dmitrii M.,Fukin, Georgy K.,Baranov, Evgenii V.,Kurskii
, p. 3935 - 3942 (2008/10/09)
The reaction of anhydrous YCl3 with an equimolar amount of lithium N,N′-dicyclohexyl-N″-bis-(trimethylsilyl)guanidinate, Li[(Me3Si)2NC(NCy)2], in THF afforded the monoguanidinate dichloro complex [{(Me3Si)2NC(NCy) 2}Y{(μ-Cl)2Li(THF)2}(μ-Cl)]2 (1). X-ray diffraction study showed that complex 1 has a bimetallic tetranuclear dimeric core with six μ2-bridging chloro ligands. Treatment of complex 1 with 4 molar equiv of LiCH2SiMe3 in hexane at 0°C yielded the monomeric salt-free dialkyl complex {(Me3Si) 2NC(NCy)2}Y(CH2SiMe3) 2(THF)2 (2). The monoguanidinate tetramethyl ate-complex {(Me3-Si)2NC(NCy)2}Y[(μ-Me) 2Li(TMEDA)]2 (3) was prepared by the reaction of complex 1 with 8 equiv of MeLi in the presence of excess TMEDA in toluene at 20°C. The complexes 2 and 3 were structurally characterized. Alkylation of complex 1 with t-BuLi (1:4 molar ratio) in hexane resulted in the formation of the bis(guanidinate) alkyl yttrium complex {(Me3Si)2NC(NCy) 2}2Y(t-Bu) (4) in 42% yield. The guanidinate ligand redistribution was also observed in the reaction of the mono(guanidinate) dichloro yttrium complex {(Me3Si)2NC(NCy) 2}YCl2(Et2O) (5) with 2 molar equiv of LiCH2SiMe3 in hexane at 0°C. This reaction afforded ate-complex {(Me3Si)2NC(NCy)2} 2Y(μ-CH2SiMe3)2Li (6) in 34% yield. The X-ray diffraction study has revealed a low formal coordination number of the lithium atom in 6 and its agostic interaction with two methyl carbon atoms of SiMe3 groups.
