Structural analysis and catalytic activity of tetranuclear metal carboxylate clusters with a [KZn3(μ3-OH)(OOCCPh3)6] or [Zn4(μ4-O)(OOCCPh3)6] central motif†
Abstract
In this work, three new tetranuclear triphenylacetato zinc–potassium or zinc compounds, namely [KZn3(μ3-OH)(OOCCPh3)6(MeCN)] (1), [Zn4(μ4-O)(OOCCPh3)6(MeCN)] (2), and [Zn4(μ4-O)(OOCCPh3)6(MeCN)2] (3) were obtained by the reaction of potassium triphenylacetate (Ph3CCOOK) with ZnCl2 in MeCN solution. It was established that the formation of crystalline 1–3 depends on the time of crystallization. Compound 1 crystallizes first, then compound 2, and finally compound 3. Compounds 1 and 2 have similar structures, which are based on the [KxZn4−x(μ3-OH)x(μ4-O)1−x(OOCCPh3)6(MeCN)] central motif (where x = 1 for 1 and 0 for 2), and undergo cocrystallization in solution to form [KZn3(μ3-OH)(OOCCPh3)6(MeCN)]0.92·[Zn4(μ4-O)(OOCCPh3)6(MeCN)]0.08 (1·2). It was therefore impossible to isolate 2 in an analytically pure form. The use of compounds 1 and 3 as initiators for the ring-opening polymerization of L-lactide under bulk conditions was investigated. The key factors that affect the catalytic activity and the physicochemical properties of the obtained polymers were identified. It was established that replacement of the K+ ion and bridging OH group in 1 by a Zn2+ ion and the O2− group found in 3 increased the thermal stability and catalytic activity of the tetranuclear system.
![Graphical abstract: Structural analysis and catalytic activity of tetranuclear metal carboxylate clusters with a [KZn3(μ3-OH)(OOCCPh3)6] or [Zn4(μ4-O)(OOCCPh3)6] central motif](/en/Image/Get?imageInfo.ImageType=GA&imageInfo.ImageIdentifier.ManuscriptID=D0NJ02540B&imageInfo.ImageIdentifier.Year=2020)
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