Reactions of molybdenum and tungsten oxide tetrafluoride with sulfur(IV) Lewis bases: structure and bonding in [WOF4]4, MOF4(OSO), and [SF3][M2O2F9] (M = Mo, W)
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Date
2020
Authors
Turnbull, Douglas
Chaudhary, Praveen
Leenstra, Dakota
Hazendonk, Paul
Wetmore, Stacey D.
Journal Title
Journal ISSN
Volume Title
Publisher
American Chemical Society
Abstract
The structure of [WOF4]4 has been reinvestigated
by low-temperature X-ray crystallography and DFT (MN15/def2-
SVPD) studies. Whereas the W4F4 ring of the tetramer is planar
and disordered in the solid state, the optimized gas-phase geometry
prefers a disphenoidally puckered W4F4 ring and demonstrates
asymmetric fluorine bridging. Dissolution of MOF4 (M = Mo, W)
in SO2 and SF4 results in the formation of MOF4(OSO) and
[SF3][M2O2F9], respectively. Both SO2 adducts and [SF3]-
[Mo2O2F9] have been characterized by X-ray crystallography.
The crystal structure of [SF3][Mo2O2F9] reveals dimerization of
the ion pair that results in a rare heptacoordinate sulfur center.
Optimization of the {[SF3][M2O2F9]}2 dimers in the gas phase,
however, results in the elongation of one contact such that the
sulfur centers are effectively hexacoordinate. Meanwhile, the crystal structure of [SF3][W2O2F9]·HF instead demonstrates
hexacoordinate sulfur centers and a highly unusual coordination to [SF3]+ from [W2O2F9]−through an oxido ligand. While
[SF3][W2O2F9] does not decompose at ambient temperature, MOF4(OSO) and [SF3][Mo2O2F9] are unstable toward evolution of
SO2 or SF4. Computational studies reveal that the monomerization of [WOF4]4 in the gas phase at 25 °C is thermodynamically
unfavorable using SO2, but favorable using SF4, consistent with the relative thermal stabilities of WOF4(OSO) and [SF3][W2O2F9].
Description
Accepted author manuscript.
Keywords
Adducts , Metal organic frameworks , Mathematical methods , Ligands
Citation
Turnbull, D., Chaudhary, P., Leenstra, D., Hazendonk, P., Wetmore, S. D., & Gerken, M. (2020). Reactions of molybdenum and tungsten oxide tetrafluoride with sulfur(IV) Lewis bases: structure and bonding in [WOF4]4, MOF4(OSO), and [SF3][M2O2F9] (M = Mo, W). Inorganic Chemistry, 59(23), 17544-17554. https://dx.doi.org/10.1021/acs.inorgchem.0c02783?ref=pdf