Abstract : The results presented in this thesis project describe the study of ruthenium complexes enclosing terminal phosphinidene Ru(η6-arene)(L)(=PR) (arene = benzene, p-cymene, tri-iso-propylbenzene; L = phosphine, phosphite, isonitrile ; R = benzene, tri-tert-butylbenzene, ferrocenylmethyl).
The first part is a bibliographic update regarding the chemistry of stable phosphinidene complexes. We have mentioned the metal-phosphinidene bond manner, the different paths to synthetically achieve these compounds, their spectroscopic and structural features as well as their reactivity.
The second part is dedicated to the synthesis of the ruthenium nucleophiles phosphinidenes complexes. Two methods of synthesis, the transmetallation and the dehydrohalogenation, have been used to attain these compounds. The influence of the steric and electronic effects of the ligands and of the substituent on the phosphinidene, on the nature of the complex and their spectroscopic and structural properties has been also examined in detail.
Finally, in the last part, the reactivity of the ruthenium complexes has been carried out. This work allowed putting in evidence the ambivalent behavior of these compounds. Indeed, if their nucleophile character results in a reactivity with the electrophiles (Lewis and Brönsted acids, alkyl halogens), the phosphinidene complexes may react with electron rich species, such as the alkynes. A deepened mechanistic study showed the determining role performed by the steric effects in this behavior of the phosphinidene complexes. Finally, a quite original reactivity has been described using oxidizers, mainly with oxygen. In this case, it permitted the synthesis and the characterization of the first monomeric metaphosphonates. These are stabilized through complexation by an organometallic ruthenium fragment presenting a η2-PO coordination, completely unprecedented in now-a-days literature. On the other hand, this complexation leads to an unexpected nucleophilic behavior since the free metaphosphonates are known to be powerful electrophiles.