Volatile and Thermally Stable Polymeric Tin Trifluoroacetates

• Published in: Inorganic chemistry 2020-01, Vol.59 (2), p.996-1005
• Main Authors: Bačić, Goran, Rankine, Conor D, Masuda, Jason D, Wann, Derek A, Barry, Seán T
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b01308

Tin trifluoroacetates are effective vapor phase single-source precursors for F-doped SnO2, but their structures have been poorly understood for decades. Here we undertook a comprehensive structural analysis of these compounds in both the solid and gas phases through a combined single-crystal X-ray crystallography, gas phase electron diffraction, and density functional theory investigation. Tin­(II) bis­(trifluoroacetate) (1) thermally decomposes into a 1:1 mixture of 1 and ditin­(II) μ-oxybis­(μ-trifluoroacetate) (2) during sublimation, which then polymerize into hexatin­(II)-di-μ3-oxyoctakis­(μ-trifluoroacetate) (3) upon solidification. Reversible depolymerization occurred readily upon heating, making 3 a useful vapor phase precursor itself. Tin­(IV) tetrakis­(trifluoroacetate) (5) was also found to be polymeric in the solid state, but it evaporated as a monomer over 130 °C lower than 3. This counterintuitive improvement in volatility by polymerization was possibly due to the large entropy change during sublimation, which offers a strategic new design feature for vapor phase deposition precursors.