%0 Journal Article %1 hlwoodcock:Christe1997 %A Christe, K. O. %A Dixon, D. A. %A Schrobilgen, G. J. %A Wilson, W. W. %D 1997 %J JOURNAL OF THE AMERICAN CHEMICAL SOCIETY %K bibtex-import %N 17 %P 3918--3928 %T Tetrafluorophosphate anion %V 119 %X The elusive POF4- anion has been characterized for the first time. It is formed from N(CH3)(4)F and POF3 in CHF3 solution at -140 degrees C and can be observed at this temperature by F-19 and P-31 NMR spectroscopy. Between -140 and -100 degrees C it reacts with POS forming the OF2P-O-PF5- anion, which, at higher temperatures, reacts with F- anions to give PO2F2- and PF6-. This reaction sequence provides a low activation energy barrier pathway for the highly exothermic dismutation of pseudo-trigonal-bipyramidal POF4- to tetrahedral PO2F2- and octahedral PF6- and explains the previous failures to isolate POF4- salts. In addition to POF4-, OF2POPF5-, and PO2F2-, the protonated form of OF2POPF5-, i.e., HOF2POPF5, was also identified as a byproduct by NMR spectroscopy. The structure, vibrational spectra, force field, NMR parameters, and dismutation energy of POF4- were calculated by nb initio electronic structure methods using, where required, the closely related and well-known PF4- ion and POF3, PF3, SOF4, and SF4 molecules for the determination of scaling factors. Although the structures and dismutation energies of isoelectronic POF4- and SOF4 are very similar, their dismutation behavior is strikingly different. While POF4- dismutates rapidly at low temperatures, SOF4 is kinetically stable toward dismutation to SO2F2 and SF6. This fact is attributed to the lack of a low activation energy barrier pathway for SOF(4)7. Furthermore, the dismutation energy calculations for POF4-, SOF4, and ClOF3 revealed very large errors in the previously published thermodynamic data for the heats of formations of SO2F2 and SOF4 and the dismutation reaction energy of POF4-. Energy barriers and the C-4v transition states for the Berry-style pseudorotational exchange of equatorial and axial fluorines in POF4-, SOF4, PF4-, and SF4 were also calculated and can account for the observation that on the NMR time scale the exchange in PF4- and SF4 can be frozen out at about -40 degrees C, while in POF4- and SOF4 it is still rapid at -140 and -150 degrees C, respectively.

@article{hlwoodcock:Christe1997, abstract = {The elusive POF4- anion has been characterized for the first time. It is formed from N(CH3)(4)F and POF3 in CHF3 solution at -140 degrees C and can be observed at this temperature by F-19 and P-31 NMR spectroscopy. Between -140 and -100 degrees C it reacts with POS forming the OF2P-O-PF5- anion, which, at higher temperatures, reacts with F- anions to give PO2F2- and PF6-. This reaction sequence provides a low activation energy barrier pathway for the highly exothermic dismutation of pseudo-trigonal-bipyramidal POF4- to tetrahedral PO2F2- and octahedral PF6- and explains the previous failures to isolate POF4- salts. In addition to POF4-, OF2POPF5-, and PO2F2-, the protonated form of OF2POPF5-, i.e., HOF2POPF5, was also identified as a byproduct by NMR spectroscopy. The structure, vibrational spectra, force field, NMR parameters, and dismutation energy of POF4- were calculated by nb initio electronic structure methods using, where required, the closely related and well-known PF4- ion and POF3, PF3, SOF4, and SF4 molecules for the determination of scaling factors. Although the structures and dismutation energies of isoelectronic POF4- and SOF4 are very similar, their dismutation behavior is strikingly different. While POF4- dismutates rapidly at low temperatures, SOF4 is kinetically stable toward dismutation to SO2F2 and SF6. This fact is attributed to the lack of a low activation energy barrier pathway for SOF(4)7. Furthermore, the dismutation energy calculations for POF4-, SOF4, and ClOF3 revealed very large errors in the previously published thermodynamic data for the heats of formations of SO2F2 and SOF4 and the dismutation reaction energy of POF4-. Energy barriers and the C-4v transition states for the Berry-style pseudorotational exchange of equatorial and axial fluorines in POF4-, SOF4, PF4-, and SF4 were also calculated and can account for the observation that on the NMR time scale the exchange in PF4- and SF4 can be frozen out at about -40 degrees C, while in POF4- and SOF4 it is still rapid at -140 and -150 degrees C, respectively.}, added-at = {2006-06-16T05:03:46.000+0200}, author = {Christe, K. O. and Dixon, D. A. and Schrobilgen, G. J. and Wilson, W. W.}, biburl = {https://www.bibsonomy.org/bibtex/2453cd3715486501ffdd70735ce77f1d8/hlwoodcock}, citeulike-article-id = {569683}, interhash = {98d4f6c72f6bcab2ae9746a9ac8626e0}, intrahash = {453cd3715486501ffdd70735ce77f1d8}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, keywords = {bibtex-import}, number = 17, pages = {3918--3928}, priority = {2}, timestamp = {2006-06-16T05:03:46.000+0200}, title = {Tetrafluorophosphate anion}, volume = 119, year = 1997 }