- Phosphaalkyne
but does not exist outside the laboratory.
There are two types of phosphaalkynes. One type of phosphaalkyne is a heavier analogue of nitriles (R-C≡N). Another type of phosphaalkyne has a five-valent three coordinate phosphorus. This molecule can also be described as
ylide or a phosphinocarbene . The phosphorus pendant of theisonitrile s R-P+≡C- called isophosphaalkynes has never been observed.In 1950, H. Albers reported the first indication of the existence of the parent compound of phosphaalkynes (type A), H-C≡P. This compound was identified by infrared absorption spectrometry and its synthesis was improved by Manfred Regitz in 1987. The synthesis of the first kinetically stable phosphaalkyne, which has a
tert-butyl group as a substituent R, was reported in 1981. These phosphaalkynes exhibit 1,2-addition reaction s andcycloaddition s in their reactivity.In 2000, Guy Bertrand reported the first structure of the type B phosphaalkyne. Its P-C-R
bond angle is 152.6 degrees, so this type of phosphaalkyne may be best described by a phosphorus vinyl ylide structure (B2).The cyaphide ion P≡C- as the phosphorus
cyanide cousin is not known as a salt and only observed in the gas phase.In silico measurements reveal that the -1 charge in this ion is location mainly on carbon (0.65). On the other hand the molecule does exist as a terminalligand in a certainruthenium transition metal complex trans- [(dppe)2Ru-(H)(C≡P)] stabilized bydppe ["Making the True "CP" Ligand." Cordaro et. alAngew. Chem. Int. Ed. 2006, 45, 6159 - 6162 DOI|10.1002/anie.200602499] .References
Wikimedia Foundation. 2010.