Effects of steric/basic properties of Lewis bases on the degree of aggregation of zinc(II) pivalate complexes

Abstract

A triangular [Zn 3( μ 3-OH)(OC(O) t Bu)( μ 2 - κ 1 O: κ 1 O′–O 2C t Bu) 4(3,5-lutidine) 3] ( 1), a paddlewheel based dinuclear [Zn( μ 2- κ 1 O: κ 1 O′–O 2C t Bu) 2L] 2 [L = 2,4-lutidine ( 2), 3,4-lutidine ( 3), and 2,3-lutidine ( 4)] and an hourglass based linear trinuclear [Zn 3( μ 2 - κ 1 O: κ 1 O′-O 2C t Bu) 6(pyridine) 2] ( 5) complexes were synthesized to understand the role of subtle steric/basic properties of Lewis bases on the degree of aggregation of the products. The mononuclear Zn(OC(O) t Bu) 2·2H 2O was also prepared in order to probe the origin of the μ 3-OH moiety in complex 1. Complexes 1– 5 and Zn(OC(O) t Bu) 2·2H 2O were characterized by microanalytical, IR, TGA/DTA, solution ( 1H and 13C) NMR, solid-state cross-polarization magic angle spinning (CP-MAS) 13C NMR, mass spectral data and single crystal X-ray diffraction data. Complex 1 represents the first example of a discrete trinuclear zinc(II) carboxylate complex that contains a [Zn 3( μ 3-OH)] 5+ core with zinc atoms in three distinct geometries namely a distorted tetrahedral, trigonal bipyramidal, and octahedral. A plausible mechanism for the formation of complexes 1– 5 was explained with the aid of point zero charge (pzc) model.