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The synthesis and reactivity of two new bis(phosphinimine)carbazole ligands [(PippN=P[Me.sub.2]).sub.2]DMC ([HL.sub.A], 3) and [(PippN=P([C.sub.4][H.sub.8])).sup.2] DMC ([HL.sub.B], 10), where Pipp = para-isopropylphenyl and DMC = 3,6- dimethylcarbazole, are reported. Dialkyl lutetium complexes of 3 and 10 were prepared in the presence of DMAP and THF by reaction of the proteo ligands with the new trialkyl reagent, Lu[(C[H.sub.2]Si[Me.sub.3]).sub.3][(DMAP).sub.2] (4) as well as Lu[(C[H.sub.2]Si[Me.sub.3]).sub.3][(THF).sub.2]. For both ligands 3 and 10, the resulting lutetium complexes were prone to intramolecular cyclometalative alkane elimination reactions whereby the location of cyclometalation was influenced by the identity of the ancillary ligand coordinated to the metal. For ligand 3, cyclometalation of two [PMe.sup.2] groups generated the complex ([L.sub.A]-[κ.sup.3]N,[κ.sup.2]C)Lu[(DMAP).sub.2] (5), whereas ligand 10 resulted in the single ortho-metalation of a paraisopropylphenyl ring to afford ([L.sub.B]-[κ.sup.3]N, κC)Lu(C[H.sub.2]Si[Me.sub.3]) (12). When complexed with scandium, ligand 10 behaved differently; double cyclometalation of two phospholane moieties resulted in the species ([L.sub.B]- [κ.sup.3]N,[κ.sup.2]C)Sc (15). The nature of the cyclometalation reactivity of ligands 3 and 10 is supported by X-ray crystallography and kinetic analysis, respectively. Key words: ligand design, rare earth, scandium, lutetium, phosphinimine, cyclometalation. Les presents travaux rendent compte de la synthese et de la reactivite de deux nouveaux ligands de type bis(phosphinimine)carbazole, [(PippN=P[Me.sub.2]).sub.2]DMC ([HL.sub.A], 3) et le [(PippN=P([C.sub.4][H.sub.8])).sub.2]DMC ([HL.sub.B], 10), ou Pipp = para-isopropylphenyle et DMC = 3,6-dimethylcarbazole. Les complexes de dialkylluthenium derives des ligands 3 et 10 ont ete prepares en presence DMAP ou de THF par reaction des proteoligands avec le nouveau reactif trialkyle Lu[(C[H.sub.2]Si[Me.sub.3]).sub.3][(DMAP).sub.2] (4) ou avec le reactif Lu[(C[H.sub.2]Si[Me.sub.3]).sub.3][(THF).sub.2]. Dans le cas des deux ligands (3 et 10), les complexes de lutecium obtenus etaient sensibles aux reactions intramoleculaires d'elimination d'alcane par cyclometallation, par lesquelles la position de la cyclometallation etait influencee par la nature du ligand auxiliaire coordonne au metal. Dans le cas du ligand 3, la cyclometallation de deux groupements [PMe.sub.2] a produit le complexe ([L.sub.A]-[κ.sup.3]N, [κ.sup.2]C)Lu[(DMAP).sub.2] (5) tandis que le ligand 10 a subi l'ortho-metallation d'un seul cycle para-isopropylphenyle, produisant le complexe ([L.sub.B]-[κ.sup.3]N, κC)Lu(C[H.sub.2]Si[Me.sub.3]) (12). Le ligand 10, lorsque complexe avec le scandium, s'est comporte differemment : une double cyclometallation des deux groupements phospholane a produit l'espece ([L.sub.B]- [κ.sup.3]N, [κ.sup.2]C)Sc (15). La nature de la reactivite des ligands 3 et 10 face a la cyclometallation a ete elucidee par radiocristallographie et analyse cinetique, respectivement. Mots-cles : conception de ligand, terres rares, scandium, lutecium, phosphinimine, cyclometallation., Introduction A fine balance is required when tuning the steric properties of an ancillary ligand for use in rare earth metal chemistry. Sufficiently sterically demanding groups must be retained on [...]