The new type of [Zr6(μ3-O)4(μ3-OH)4] cluster core:: Crystal structure and spectral characterization of [Zr6O4(OH)4(OOCR)12] (R = But, C(CH3)2Et)

Hexanuclear Zr(IV) oxo carboxylate derivatives of the general formula [Zr6O4(OH)(4)(OOCR')(12)] (R' = Bu' (1), C(CH3)(2)Et (2)) were synthesized from Zr(OR)(4) (R = Pr', C(CH3)(2)Et) and appropriate organic acids (HOOCR', R'= Bu, C(CH3)(2)Et) in a molar ratio 1:2. The crystal structures of 1 and 2 were solved in the centrosymmetric R3 space group. Zirconium atoms form hexanuclear Zr(IV) clusters, linked by 4:4 system of mu(3)-oxo/hydoxo bridges and stabilized by syn-syn carboxylate groups. Each of the metal ions is surrounded by eight oxygen atoms derived from four mu(3)-O; OXO/hydroxo bridges, and four mu-O; carboxylate ones. Analysis of crystallographic and spectroscopic data suggests that four protons migrate between eight oxide bridges of the [Zr6O4(OH)(4)(OOCR')(12)] cluster. Thermogravimetric and temperature variable (VT IR) studies have been carried out in order to determine the thermal behaviors of 1 and 2. (c) 2006 Elsevier Ltd. All rights reserved.