Chloro, Alkyl and Aryl Complexes of Rare Earth Metals Supported by Bulky Tetrasubstituted Guanidinate Ligands

The reactions of anhydrous LnCl3 (Ln = Y, Nd, Sm, Lu) with two equiv. of sodium N,N′‐dicyclohexyl‐N′′‐bis(trimethylsilyl)guanidinate Na[(Me3Si)2NC(NCy)2], obtained from Na[N(SiMe3)2] and the 1,3‐dicyclohexyl‐substituted carbodiimide CyN=C=NCy in THF, yield the monochloro bis(guanidinate) tetrahydrofuranate complexes [(Me3Si)2NC(NCy)2]2LnCl(THF) [Ln = Y (1), Nd (2), Sm (3) and Lu (4)]. The analogous reactions of YCl3 and LuCl3 with the lithium guanidinate [Li(Et2O)][(Me3Si)2NC(NCy)2] afford the bis(guanidinate) “ate” complexes [(Me3Si)2NC(NCy)2]2Ln(μ‐Cl)2Li(THF)2 [Ln = Y (5) and Lu (6)]. Treatment of 5 with dimethoxyethane results in the formation of [(Me3Si)2NC(NCy)2]2Y(μ‐Cl)2Li(DME) (7). The carbyl complexes [(Me3Si)2NC(NCy)2]2Y‐tBu] (8), [(Me3Si)2NC(NCy)2]2Y(μ‐Me)2Li(TMEDA) (10) and [(Me3Si)2NC(NCy)2]2YPh(THF) (13) were obtained by interaction of complex 1 with RLi (R = tBu, Me or Ph). The molecular structures of 1, 6, 7, 8 and the side product [Li(TMEDA)][(Me3Si)2NC(NCy)2] have been determined by single‐crystal X‐ray analyses. Agostic interactions between the yttrium atom and the tert‐butyl group in complex 8 in the solid state as well as in solution have been substantiated by 13C NMR spectroscopy and X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)