The implication of titanocene and zirconocene complexes in phosphinine
chemistry is reviewed. Two approaches to polyfunctional phosphinines
using dimethyltitanocene as starting precursor have been developed so
far. The first one involves the thermal rearrangement of 1-alkynyl-dih
ydrophosphetes. The second relies on the reactivity towards alkynes of
1,3,2-diazaphosphinines which are obtained by a metal transfer reacti
on from the corresponding diazatitanacycle. (2-Phosphininyl)-halogenoz
irconocene complexes, prepared by insertion of zirconocene into the ca
rbon-halogen bond of 2-halogenophosphinines, have found interesting ap
plications in the synthesis of alpha-functionalized compounds and 2,2'
-biphosphinines upon reaction with electrophiles and nickel(0) complex
es, respectively. Another important development of their chemistry is
provided by the synthesis of monomeric and dimeric phosphabenzyne-zirc
onocene complexes. Preliminary investigations have shown that their re
activity closely mimics that of their carbon counterparts. Various mol
ecules such as polar alkynes, aldehydes, ketones, nitriles, phosphine
sulfides, insert into the carbon-zirconium bond of these complexes to
give a wide range of annelated metallacycles which can be subsequently
transformed into functional phosphinines upon acidic hydrolysis. (C)
1998 Elsevier Science S.A. Al rights reserved.