Phosphorus bond enthalpy terms

The P2 molecule, with a P=P triple bond, is unstable except at high temperatures, and P4 and other forms of phosphorus with P—P single bonds are more stable at ordinary temperatures. This behaviour is in contrast to that of nitrogen, which is stable only as N2 molecules. The difference between the two elements is a consequence of 2p-2p n bonding being more effective than 3p-3p n bonding, and of the N—N o bond being weaker than the P—P a bond. The bond enthalpy terms are listed in Table 11.3. 

Table 11.3 Molar bond enthalpy terms for some nitrogen and phosphorus bonds...

Bonds to Fluorine.—Phosphorus (m) Compounds. SCF wavefunctions for PF allow estimation of the dissociation enthalpy (4.7 eV), the dipole moment (0.6 D), and the P—F distance (1.58 A), etc.,261 while the emission spectra of the species produced by the action of microwave discharges on HPF2 and PF3 may be analysed in terms of the PF diatomic.262 Experimental data for the e.s.r. parameters of the PF2 radical263 and those calculated by ab initio methods264 are in good agreement. 

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