Noble-Gas Difluoride Complexes of MOF4 (M=Mo,W); Syntheses,Structures and Bonding of NgF2 ⋅ MOF4 and XeF2 ⋅ 2MOF4 (Ng=Kr,Xe) |
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Authors: | Mark R. Bortolus Dr. Hélène P. A. Mercier Dr. David S. Brock Prof. Gary J. Schrobilgen |
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Affiliation: | Department of Chemistry, McMaster University, Hamilton, ON L8S 4M1 Canada |
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Abstract: | The NgF2 ⋅ MOF4 (Ng=Kr, Xe; M=Mo, W) and XeF2 ⋅ 2MOF4 complexes were synthesized in anhydrous HF (aHF) solvent and melts, respectively. Their single-crystal X-ray diffraction (SCXRD) structures show NgF2 ⋅ MOF4 and XeF2 ⋅ 2MOF4 have Ft−Ng−Fb- - -M arrangements, in which the NgF2 ligands coordinate to MOF4 through Ng−Fb- - -M bridges. The XeF2 ligands of XeF2 ⋅ 2MOF4 also coordinate to F3OM−Fb’- - -M'OF4 moieties through Xe−Fb- - -M bridges to form Ft−Xe−Fb- - -M(OF3)−Fb’- - -M'OF4, where XeF2 coordinates trans to the M=O bond and Fb’ coordinates trans to the M’=O bond. The Ng−Ft, Ng−Fb, and M- - -Fb bond lengths of NgF2 ⋅ nMOF4 are consistent with MOF4 and F3OM−Fb’- - -M'OF4 fluoride-ion affinity trends: CrOF444≈F3OMo−Fb’- - -Mo'OF43OW−Fb’- - -W'OF4. The [- -(F4OMo)(μ3-F)H- - -(μ-F)H- -]∞ solvate was also synthesized in aHF and characterized by SCXRD. Quantum-chemical calculations show the M- - -Fb bonds of NgF2 ⋅ MOF4 and XeF2 ⋅ 2MOF4 are predominantly electrostatic, σ-hole type bonds. |
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Keywords: | σ-hole bonding group 6 oxide tetrafluoride chemistry noble-gas chemistry Raman spectroscopy X-ray crystallography |
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