The Photoeleci-ron Spectrum of Phosphorus Pentafluoride
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چکیده
Phosphorus pentafluoride plays an important role in phosphorus chemistry for both stereochemical and theoretic31 reasons. Several semi-empiricnl moleculnr orbital calculations have been carried out on PF, [l-5] in an effort to elucidate its electronic structure. However, reference to table 1 indicates a generally unsatisfactory agreement between these calculations regarding both the sequencing and the magnitudes of the eigenvalues. In view of the foregoing it seemed appropriate to determine the photoelectrcn (PE) spectrum of PF,. Taking the ground state geometry of PF, to be trigonal bipyramidal [6] (Dsh) and assuming that the F(2s) orbitals are of too low energy to be detectsb!e by He I photoelectron spectroscopy* it is possible to predict a total of ten PE bands. The six non-bonding x-type combinations of F(2p) orbitals are of symmetry a;, a;, e’(2), and e”(2) and the four P-F(2p) u-bonding orbit& transform as a; (2), a;, and e”. Intuitively one expects most of the non-bonding orbitals to be of higher energy than the P-F u-bonding crbitals, a view which is generally substantiated by the molecular orbital calculations (table 1). The preceding qualitive discussion is, of course, based on the implicit assumption of no sigma-pi mfilg. Using the apparatus and techniques described elsewhere [g] it is possible to detect the first six PE bands of PFS (fig. I). The high relative intensities of the fist
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تاریخ انتشار 2001