The stability of phosphaalkynes R-C≡P (R = -BH₂, -CH₃, -NH₂, -OH) and their isomers

B3LYP and CCSD(T) methods were employed to investigate the systems of R-C≡P (R = -BH₂, -CH₃, - NH₂, -OH). The results indicate that isomers P≡C-BH₂ and CH₃-C≡P containing C≡P triple bond are thermodynamically the most stable species in BH₂-C≡P and CH₃-C≡P systems, respectively. But in the systems of HO-C≡P and NH₂-C≡P, H-P=C=O and N≡C-PH₂ containing C≡N triple bond are thermodynamically the most stable species, respectively. The calculated results on the kinetic stability indicate that for R-C≡P (R = -BH₂, -NH₂) systems, in which no experimental information are available, five isomers are kinetically stable. In HO-C≡P system, two kinetically stable species are located. Isomer H-P=C=O has been detected in experiment, and in view of higher kinetic stability, another isomer HO-C≡P should be experimentally observable. For CH₃-C≡P system, isomer CH₃-C≡P has been observed in experiment, and another kinetically stable isomer HC≡C-PH₂ ought to be detected in future experiments.