Abstract:
Measurements of the heats of iodination of hexakis(trifluorophosphine)chromium(0) and of tetrakis(trifluorophosphine)nickel(0) were carried out by high temperature microcalorimetry. Standard enthalpies of formation were derived: ΔH°f(Ni(PF3)4, liq)=–961.9 ± 3 kcal mol–1(–4025 ± 12 kJ mol–1), ΔH°f(Cr(PF3)6, c)=–1446.4 ± 4 kcal mol–1(–6052 ± 17 kJ mol–1).
The mean bond dissociation energies, D(Ni—PF3) and D(Cr—PF3) were evaluated as 35.2 ± 0.8 and 25.5 ± 1 kcal mol–1 respectively; these values compare very closely with the values D(Ni—CO) and D(Cr—CO) in Ni(CO)4 and Cr(CO)6.
