Compounds with One- and Two-Connected P Atoms

Bonding of the 3jt p(P)-2jt p(C) type is now generally believed to be present in the trivalent phosphorus compounds indicated in Table 6.13. Such compounds have proved invaluable in the synthesis of organophosphorus ring and cage derivatives. It is believed that the chemical behaviour of P=C bonds mimics that of alkenes very closely [15]. 

The simplest 1- and 2-connected organophosphorus compounds based on trivalent phosphorus are methinophosphide, H-C=P, and methylene phosphine, H2C=PH. Many acyclic derivatives based on a single P atom have been made. 

---