Mass Spectrometric Studies at High Temperatures. IX. The Sublimation Pressure of Copper(II) Fluoride

Abstract

The molecules need not have over-all planar symmetry but planarity would probably be retained in the individual boroxine rings. We can visualize the formation of H4B607 as elimination of a H2 molecule in a reaction of H3B303 at a B-H bond with HzB303(0H) at the 0-H bond. Similarly, H4B404 could be formed from H3B303 and HzB(0H) (hydroxyborane) .* Ion currents of HBO+ and HBOH+ are always observable in these experiments but, because these ions are formed by fragmentation from a number of precursors, it is difficult to assess the importance of the molecular contribution of HBO and HzBOH. These species may be important in the kinetics of reaction as precursors to boroxine.The pressure dependences of reactions 1 and 3 show that the equilibrium concentrations of H4B404 and H4B6-0 7 should increase relative to H3B303 as the pressure of H3B303 increases. Relatively high concentrations of H4B404 and H4Be07 should be possible in a static system where the partial pressure of Hz over B-Bz03 mixtures is of the order of 1 atm at temperatures near 1400'K.Mass spectrometric studies of CuFz sublimation from a Knudsen cell have established CuFz(g) as the major vapor species and AH"~~~[sublimation] = 63.9 f 1.0 kcal mole-'. The dissociation energy of CuF(g) is 87 f 9 kcal mole-' (3.8 f 0.4 ev).

Vapor Pressures and Sublimation Enthalpies of Copper Difluoride and Silver(I, II) Fluorides by the Torsion−Effusion Method

“…The vapor pressures measured in the present work are compared, in Table 4, with those reported in the literature. Our data are lower than those measured by Kent et al 1 and comparable, even if with a lower slope, with those measured by Ehlert and Wang 2 (see Figure 2).…”

“…The average third-law value, ∆ sub H°(298 K) ) 261 ( 1 kJ • mol -1 , is in agreement with the second-law one. Giving equal weight to second-and third-law results, the final standard Our results are compared in Table 4 with those proposed by Kent et al 1 and by Ehlert and Wang 2 and with those by us, recalculated using the vapor pressures reported in their works 1,2 and the IVTANTHERMO database 9 thermodynamic functions.…”

Ab initio Study of the Diatomic Fluorides FeF, CoF, NiF, and CuF

“…It is interesting that the first emission spectrum of CuF was observed by Robert S. Mulliken as early as 1925 . Since then, we are aware of at least 22 experimental spectroscopic works on CuF. ,− The most recent and pertinent experimental results will be contrasted with ours later on.…”

Thermochemistry of the copper fluorides

“…Considerable attention was devoted to the study of the monomer CuF since the ionization potential (IP) and dissociation energy reported by Hildenbrand3 were not in agreement with the values given by Margrave and co-workers. 4 An examination of the solid phase formed when CuF2 is heated under reducing conditions also seemed worthwhile since a patent5 has been issued for the preparation of CuF(c) even though von Wartenberg6 found CuF to be a metastable solid and several other attempts7 to produce CuF(c) failed. Consequently, thermal analysis and x-ray diffraction methods were used to study CuF2 under reducing as well as neutral conditions from ambient temperature to over 1100 K.…”