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The reaction of 1,3,5-[([.sup.i][Pr.sub.2]]PO).sub.3][C.sub.6]H3 with [Co.sub.2][(CO).sub.8] leads to the isolation of a POCOP-type mononuclear pincer complex {[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-[([.sup.i][Pr.sub.2]]PO).sub.3]C6[H.sub.2]}Co[(CO).sub.2] [(1) or a tetranuclear species {[K.sup.P]-{[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-[([.sup.i][Pr.sub.2]]PO).sub.3][C.sub.6][H.sub.2]}Co[(CO).sub.2]}.sub.2][Co.sub.2][(CO).sub.6] (2), depending on the ligand to cobalt ratio employed. The latter compound can be an impurity during the synthesis of {2,6-[([.sup.i][Pr.sub.2]]PO).sub.2]-4-[Me.sub.2]N-[C.sub.6][H.sub.2]}Co[(CO).sub.2], when the ligand precursor 5-(dimethylamino)resorcinol is contaminated with phloroglucinol due to incomplete monoamination. Similarly, the reaction of 1,3,5-[( [.sup.i][Pr.sub.2]]PO).sub.3]C6H3 with [NiCl.sub.2] in the presence of 4-dimethylaminopyridine provides {[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-[([.sup.i][Pr.sub.2]]PO).sub.3][C.sub.6][H.sub.2]}NiCl (3) bearing an appended phosphinite group. Structures 1-3 have been studied by X-ray crystallography. Key words: phosphinite, pincer complexes, C-H activation, appended functionality, catalyst immobilization. La reaction du 1,3,5-[([.sup.i][Pr.sub.2]PO).sub.3][C.sub.6][H.sub.3] avec le [Co.sub.2][(CO).sub.8] permet d'isoler le complexe de ligand pince mononucleaire de type POCOP{[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-[([.sup.i][Pr.sub.2]PO)3[C.sub.6][H.sub.2]}Co(CO).sub.2] [(1)oul'especetetranucleaire[{[K.sup.P]-{[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-([.sup.i][Pr.sub.2]PO)3[C.sub.6][H.sub.2]}Co(CO).sub.2]}.sub.2][Co.sub.2][(CO).sub.6](2), selon le rapport ligand-cobalt utilise. Cette derniere espece peut etre une impurete issue de la synthese du {2,6-[([.sup.i][Pr.sub.2]]PO).sub.2]-4-[Me.sub.2]N-[C.sub.6][H.sub.2]}Co[(CO).sub.2], lorsque le precurseur de ligand 5-(dimethylamino)resorcinol est contamine par du phloroglucinol en raison d'une monoamination incomplete. De maniere similaire, la reaction du 1,3,5-[([.sup.i][Pr.sub.2]PO).sub.3][C.sub.6][H.sub.3] avec le [NiCl.sub.2] en presence de 4-dimethylaminopyridine produit le {[K.sup.P],[K.sup.C],[K.sup.P]-2,4,6-([.sup.i][Pr.sub.2]PO)3[C.sub.6][H.sub.2]}NiCl (3) portant un groupe phosphinite attache. Nous avons etudie les structures 1-3 par radiocristallographie. [Traduit par la Redaction] Mots-cles : phosphinite, complexes de ligands pinces, activation de liaison C-H, groupe fonctionnel attache, immobilisation du catalyseur., Introduction Diphosphinite-derived POCOP-type pincer complexes have been studied extensively as homogeneous catalysts for a wide variety of organic transformations (.1-11) To facilitate catalyst-product separation and catalyst recycling, (12), (13) Lewis [...]