Diamidosilylether complexes of yttrium(III) and chromium(III): Synthetic challenges and surprises

摘要

The synthesis, spectroscopic and structural characterization of a series of diamidosilylether complexes of yttrium(Ill) and chromium(111) are reported. Addition of one equiv. of Li-2{[(BuN)-Bu-t(SiMe2)](2)O} to YCl3 in THF generates YCl(THF){[(BuN)-Bu-t(SiMe2)](2)O} (1) in high yield; 1 was crystallized as a bis-THF adduct. Alkylation of 1 proceeds cleanly with bulky LiCH(SiMe3)(2) or NaC5H5 to yield Y[CH(SiMe3)(2)](THF){[(BuN)-Bu-t(SiMe2)](2)O} (2) and Y(eta(5)-C2H5)(THF){[(BuN)-Bu-t(SiMe2)](2)O} (3) respectively. Complex 2 was characterized by H-1 NMR spectroscopy, with the diagnostic Y-CH resonance at delta -0.84 ((2)J(YH) = 2.4 Hz), while 3 was structurally characterized and shows a diagnostic Y-C5H5 singlet at delta 6.47. Attempts to use less bulky alkylating agents resulted in a mixture of products or decomposition. Addition of two equiv. of Li-2{[tBuN(SiMe2)](2)O} to YCl3 in toluene with trace THF generates {Y{[(BuN)-Bu-t(SiMe2)](2)O}(2)}Li(THF) (4), which was structurally characterized. Complex 4 acts as a diamidosilylether ligand-transfer agent, reacting with MCl3 (M = Fe 5; Cr 6) to yield {MCl[(BuN)-Bu-t(SiMe2)](2)O}(2) along with 1. Complex 6 was structurally characterized, revealing a chloride-bridged dinuclear system containing rare five-coordinate chromium(111) centres. (c) 2005 Elsevier B.V. All rights reserved.