Volatile and Thermally Stable Polymeric Tin Trifluoroacetates

TY - JOUR

T1 - Volatile and Thermally Stable Polymeric Tin Trifluoroacetates

AU - Bačić, Goran

AU - Rankine, Conor D

AU - Masuda, Jason D

AU - Wann, Derek A

AU - Barry, Seán T

N1 - © 2020 American Chemical Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2020/1/21

Y1 - 2020/1/21

N2 - 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.

AB - 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.

U2 - 10.1021/acs.inorgchem.9b01308

DO - 10.1021/acs.inorgchem.9b01308

M3 - Article

C2 - 31916436

SN - 0020-1669

VL - 59

SP - 996

EP - 1005

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 2

ER -