Calculated heats of formation of simple phosphinidenes (phosphanylidenes, R-P)

Ab initio MO and DET calculations up to the coupled-cluster theory level, C CSD(T) with large 6-311++G(3df,2p) and cc-pVTZ basis sets, have been applie d to determine the heats: of formation of a series of simple phosphinidenes (R-P) that exhibit a triplet ground state. Three different exchange and is ogyric reactions of the type RP + HX --> HP t RX have been used as working reactions. A set of consistent values for DeltaH(f,298)degrees (R-P) are ev aluated as follows (values in kcal/mol): HICP, 47.6; H2NP. 48.6: HOP. -0.5: FP, - 12.5 (exp: -12.4); H3SiP, 61.9, H2PP, 58.0; HSP, 17.9; ClP, 30.0 (ex p: 30.8): BrP, 40.0 (exp: 38.9) with an estimated error bar of +/-2 kcal/mo l. DFT/B3LYP calculations have been found to reproduce these values with ac ceptable accuracy. Empirical corrections for the DFT/B3LYP calculations wer e estimated and heats of formation for a series of other phosphinidenes wer e also evaluated using this correction: H2FCP, 10.2; HF2CP, -43.6; F3CP, -9 6.0, H2ClCP, 46.6: H2BrCP. 56.8; O=CHP, 34.6; S=CHP, 81.2, HN=CHP, 77.3: CH 3CH2P, 45.4; H2C=CHP, 70.4: HC drop C-P, 100,5. Except for the diatomic spe cies, no experimental values for RP are available yet. (C) 2000 Elsevier Sc ience B.V. All rights reserved.