The UHF-CNDO/2 study of tetra-atomic radicals containing silicon and phosphorus

Structure and reactivity of the hypervalent phosphoranyl radicals

“…It should be pointed out however that the use of this equation to compute hfs constants is not without criticism. 54 Quantitatively, the results of both molecular orbital methods are not very good. This is especially true of the INDO method which predicts a larger 3IP hfs constant in PH4 relative to PF4, whereas experimentally the interaction constant in PF4 and its derivatives is over twice as large as that found in radicals derived from PH4.…”

CNDO/2 calculations on geometries of tetra- and pentacoordinated phosphoranyl radicals and UHF [unrestricted Hartree-Fock] calculations on tetracoordinated .pi.-ligand phosphoranyl radicals

“…Evidently, CNDO/2 calculations cannot be used to calculate spin densities in phosphorus radicals. 15,18 This is presumably also true for other second-row atoms. Another difficulty is that with CNDO/2 it is only possible to calculate relatively small-sized radicals because of the long computer times.…”