Coordination Features of the 1,3,5‐Triazapentadienyl Ligand in Alkyl Complexes of Rare‐Earth Metals

Abstract

AbstractThe reactions of 1,3,5‐triazapentadiene 2,6‐iPr2C6H3NC(Ph)NC(Ph)NHC6H3iPr2‐2,6 (1) with Ln(CH2SiMe3)3(THF)2 (Ln=Y, Lu) in hexane afford bis(alkyl) complexes [2,6‐iPr2C6H3NC(Ph)NC(Ph)NC6H3iPr2‐2,6]Ln(CH2SiMe3)2(THF) (Ln=Y (2), Lu (3)) in 58 (2) and 62 (3) % yields. The X‐ray diffraction study revealed that in 3 the triazapentadienyl ligand coordinates with the Lu3+ ion in “amidinate” fashion resulting in the formation of a four‐membered metallocycle. In contrast, the reaction of 1 with the scandium analogue Sc(CH2SiMe3)3(THF)2 in toluene proceeds with the cleavage of C−N bond of 1,3,5‐triazapentadiene and leads to the formation of a dinuclear monoalkyl complex [{μ2‐2,6‐iPr2C6H3NC(Ph)N}Sc(CH2SiMe3)(THF)]2 (4) in 43 % yield. Complex 4 features κ2‐N,N‐coordination of the residual dianionic {μ2‐2,6‐iPr2C6H3NC(Ph)N}2− ligand μ‐bridging two Sc3+ centers. Alkyl complexes 2–4 were evaluated as pre‐catalysts for isoprene polymerization and hydrosilylation of unsaturated substrates with PhSiH3.