344613-79-2Relevant academic research and scientific papers
A sterically hindered N,N,O tripod ligand and its zinc complex chemistry
Troesch,Vahrenkamp
, p. 2305 - 2311 (2001)
The new ligand bis(2-picolyl)(2-hydroxy-3,5-di-tert-butylbenzyl)amine (HL) was prepared from bis(2-picolyl)-amine and 2,4-di-tert-butyl-6-(chloromethyl)phenol. It acts as a tetradentate N,N,O tripod ligand ensuring 5-fold coordination in all its zinc complexes L·Zn-X. The central complex of the series was [L·Zn(OH2)]ClO4 (1) obtained from zinc perchlorate. Together with the more labile complex L·Zn-C2H5 (2), obtained from diethyl zinc, it was used as a starting material for ligand substitutions. In the presence of bases, 1 was converted to L·Zn-OH (3), [L·Zn(py)]ClO4 (4), and [(L·Zn)3(μ3-CO3)]ClO4 (5). Metathetical reactions produced the neutral complexes L·Zn-X with X = Br (6), OAc (7), OC6H5 (8), SC6H5 (9), OP(O)(OPh)2 (10), p-nitrophenolate (11), l-methyluracilate (12), o-formylphenolate (13), and o-hydroxymethylphenolate (14). Structure determinations of 1, 5, 7, 10, 11, 13, and 14 confirmed the strictly monodentate attachment of all units X in L·Zn-X. The hydrolytic cleavage of tris(p)-nitrophenyl) phosphate by 1 was investigated preparatively and kinetically. L·Zn-OH was found to be the hydrolytically active nucleophile. The second-order rate constant for the cleavage reaction was found to be slightly lower than the values for related systems, reflecting the steric hindrance in the tert-butyl-substituted ligand L.
