Issue 47, 2022

Reactivity of bi- and monometallic trifluoroacetates towards amorphous SiO2

Abstract

The reactivity of alkali–manganese(II) and alkali trifluoroacetates towards amorphous SiO2 (a-SiO2) was studied in the solid-state. K4Mn2(tfa)8, Cs3Mn2(tfa)7(tfaH), KH(tfa)2, and CsH(tfa)2 (tfa = CF3COO) were thermally decomposed under vacuum in fused quartz tubes. Three new bimetallic fluorotrifluoroacetates of formulas K4Mn3(tfa)9F, Cs4Mn3(tfa)9F, and K2Mn(tfa)3F were discovered upon thermolysis at 175 °C. K4Mn3(tfa)9F and Cs4Mn3(tfa)9F feature a triangular-bridged metal cluster of formula [Mn33-F)(μ2-tfa)6(tfa)3]4−. In the case of K2Mn(tfa)3F, fluoride serves as an inverse coordination center for the tetrahedral metal cluster K2Mn24-F). Fluorotrifluoroacetates may be regarded as intermediates in the transformation of bimetallic trifluoroacetates to fluoroperovskites KMnF3, CsMnF3, and Cs2MnF4, which crystallized between 250 and 600 °C. Decomposition of these trifluoroacetates also yielded alkali hexafluorosilicates K2SiF6 and Cs2SiF6 as a result of the fluorination of fused quartz. The ability to fluorinate fused quartz was observed for monometallic alkali trifluoroacetates as well. Hexafluorosilicates and heptafluorosilicates K3SiF7 and Cs3SiF7 were obtained upon thermolysis of KH(tfa)2 and CsH(tfa)2 between 200 and 400 °C. This ability was exploited to synthesize fluorosilicates under air by simply reacting alkali trifluoroacetates with a-SiO2 powder.

Graphical abstract: Reactivity of bi- and monometallic trifluoroacetates towards amorphous SiO2

Supplementary files

Article information

Article type
Paper
Submitted
29 ဩ 2022
Accepted
10 နို 2022
First published
18 နို 2022

Dalton Trans., 2022,51, 18224-18233

Author version available

Reactivity of bi- and monometallic trifluoroacetates towards amorphous SiO2

H. N. Munasinghe, M. R. Imer, R. G. Szlag, L. Suescun and F. A. Rabuffetti, Dalton Trans., 2022, 51, 18224 DOI: 10.1039/D2DT02822K

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