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Structure and Conformational Properties of Azido(difluoro)phosphane, F 2 PN 3
Author(s) -
Zeng Xiaoqing,
Beckers Helmut,
Willner Helge,
Berger Raphael J. F.,
Hayes Stuart A.,
Mitzel Norbert W.
Publication year - 2011
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000882
Subject(s) - chemistry , conformational isomerism , crystallography , raman spectroscopy , steric effects , natural bond orbital , infrared spectroscopy , spectroscopy , matrix isolation , stereochemistry , molecule , organic chemistry , physics , quantum mechanics , optics
Azido(difluoro)phosphane, F 2 PN 3 , is a colorless gas, which freezes to a glassy solid at ca. –120 °C, and the boiling point obtained by extrapolating the vapor‐pressure curve is 8 °C. It has been characterized by IR (gas phase, Ar matrix), Raman (liquid, amorphous, and crystalline solid), and 19 F, 31 P, 14 N, and 15 N NMR spectroscopy. The conformational properties of F 2 PN 3 have been studied by vibrational spectroscopy, gas electron diffraction (GED), and quantum chemical calculations. An almost equimolar mixture of two conformers was identified in the gas and neat liquid phases, as well as in Ar matrix, for which the N 3 group adopts a syn and anti orientation with respect to the bisector of the FPF angle. The syn conformer was found to be slightly more stable than the anti conformer by 2.4 ± 0.6 kJ mol –1 (Δ H °) determined by gas–phase temperature‐dependent IR spectroscopy, but in the crystalline state at low‐temperature only the anti form is observed. The very different conformational properties of F 2 PN 3 relative to that of the previously investigated F 2 PNCO are discussed, guided by a natural bond orbital (NBO) analysis of electron delocalizations and steric exchange repulsions.