Inorganic Chemistry, Vol.53, No.13, 6775-6787, 2014
Methylene-Linked Anilide-Bis(aryloxide) Ligands: Lithium, Sodium, Potassium, Chromium(III), and Vanadium(III) Ligation
The anilide bis(aryloxide) proligands H-3[ONOR] (where H-3[ONOR] = 2,6-(3-R-1-5-R-2-2-hydroxybenzyl)-4-tert-butyl-N-tolyl-aniline; H-3[ONOfBu], R-1= Bu-t, R-2 = Me; H-3[ONOMe], R-1= Me, R-2 = Bu-t; H-3[ONOMe2], R-1 = R-2= Me) were synthesized from 2-bromo-5-tert-butyl-isophthalic acid dimethyl ester in three steps in multigram scale. The ligand precursor H-3[ONOfBu] was readily doubly and triply deprotonated with alkali metal reagents to generate the related derivatives M-2[H(ONOtBu)] and M-3[ONOtBu] (M = Li, Na, K). The extent of ligand deprotonation is observed to depend on the choice of deprotonating reagents and solvents. Transmetalation reaction of the trilithium derivative Li-3[ONOtBu] with MCl3(THF)(3) (M = Cr, V; THF = tetrahydrofuran) afforded [(ONOtBu)CrCl(THF){Li(THF)}] (5) and [(ONOfBu)V(THF)] (6). The vanadium complex 6 reacted readily with 2-butyne, styrene oxide, and mesityl azide, yielding [(ONOfBu)V(eta(2)-MeCCMe)] (7), [(ONOtBu)V(O)] (8), and [(ONOtBu)-V(NMes)] (9), respectively. The solid-state structures of H-3[ONOtBu] and metal complexes were determined by X-ray crystallography. The [ONOtBu] ligand adopts a u-shaped structure in solution and solid state.