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′ = But (1), C(CH3)2Et (2)) were synthesized from Zr(OR)4 (R = Pri, C(CH3)2Et) and appropriate organic acids (HOOCR′, R′ = But, C(CH3)2Et) 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 μ3-oxo/hydoxo bridges and stabilized by syn–syn carboxylate groups. Each of the metal ions is surrounded by eight oxygen atoms derived from four μ3-O; oxo/hydroxo bridges, and four μ-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.

Graphical abstractHexanuclear Zr(IV) oxo carboxylate derivatives of the general formula [Zr6O4(OH)4(OOCR′)12] (R′ = But (1), C(CH3)2Et (2)) were synthesized from Zr(OR)4 (R = Pri, C(CH3)2Et) and appropriate organic acids (HOOCR′, R′ = But, C(CH3)2Et) in a molar ratio 1:2. The structure of these compounds consists of hexanuclear Zr(IV) clusters formed by six zirconium atoms, linked by 4:4 system of μ3-oxo/hydoxy bridges and stabilized by syn–syn carboxylate groups. Results of crystallographic and spectroscopic data suggest that in [Zr6(μ3-O4)(μ3-OH)4] clusters four protons migrate between eight oxide bridges. Thermal stability studies of 1 and 2 using TGA/DTA and VT IR methods have been carried out.Figure optionsDownload full-size imageDownload as PowerPoint slide