No abstract

No abstract

NF3, N2F4, NF2, PF3, P2F4, PF2, and PF2I have been studied by photoionization mass spectrometry. Modified or confirmatory values have been obtained for the heats of formation of NF+3, NF+2, and NF+ and the ionization potentials of NF3 and NF2. The stepwise bond energies are deduced to be D00(NF) =3.27±0.02 eV; D00(FN–F) =2.85±0.02 eV; and D00(F2N–F) =2.47±0.01 eV. Heats of formation at 0 K have been measured for PF+2 (89.6±0.5 kcal/mol), PF+ (≤214.8 kcal/mol), and PF2I (−142.3±1.0 kcal/mol). The directly measured ionization potential of PF2 is 8.85±0.01 eV. The stepwise bond energies are found to be D00(PF)

Absorption spectra of polycrystalline samples of LiUF6, α-NaUF6, and CsUF6 have been recorded at 4, 77, and 298 K. This group of compounds has a common sixfold U–F coordination that approaches an octahedral site symmetry for LiUF6 but exhibits increasing trigonal distortion (D3d symmetry) along the indicated series. Spectra have been systematically interpreted as consisting of sequences of vibronic transitions coupled to well-defined electronic excited states. Crystal-field calculations have been performed.

The title compounds have a common sixfold U‐Fcoordination that approaches an octahedral site symmetry for LiUFÖ but exhibits increasing trigonal distortion along the indicated symmetry.