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High-Throughput and in Situ Energy Dispersive X-ray Diffraction Investigation on the Formation of the New Metal Organogermanate Cu(OOCC2H4Ge)2O3

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journal contribution
posted on 07.12.2011, 00:00 by Corinna Schmidt, Norbert Stock
Using the bifunctional metalloligand bis(2-carboxyethylgermanium sesquioxide) (HOOCCH2CH2Ge)2O3, we carried out a high-throughput (HT) study in the system Cu2+/(HOOCCH2CH2Ge)2O3/H2O/2-propanol. The HT experiment included 72 individual reactions, which were employed to study the influence of the molar ratio of the starting materials and the volume fraction of the solvents on the product formation. One new compound Cu(OOCC2H4Ge)2O3 (1) (monoclinic, P21/n, a = 1348.36(4), b = 509.64(1), c = 1599.21(5) pm, β = 114.44(1)°, V = 1000.45(5) × 106 pm3, Z = 4) was obtained and characterized in detail using single crystal X-ray diffraction, scanning electron microscopy (SEM), thermogravimetric (TG) measurements, and IR spectroscopy. The title compound crystallizes in thin blue-colored needles. The crystal structure contains alternating chains of 4-rings of corner-sharing GeO3C-polyhedra and chains of Cu2O8 paddle-wheel units. Their interconnection leads to the formation of layers that are held together by van der Waals interactions. The formation of the title compound was also explored by in situ energy dispersive X-ray diffraction (EDXRD) measurements using conventional heating in the temperature range 120–140 °C. Using the Avrami-Eroféev equation and the Sharp–Hancock method, Avrami exponents in a range of 1.65–1.87 are obtained, which suggests a nucleation controlled reaction mechanism for the crystallization process. All rate constants are in the 0.029(3)–0.242(3) s–1 range, and the Arrhenius activation energy was determined to be 113(7) kJ/mol.

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