Ligand Influence on Intramolecular Cyclometalation in Bis(phosphinimine) Rare Earth Alkyl Complexes

The synthesis and reactivity of two new bis(phosphinimine)carbazole ligands (PippN=PMe2)2DMC, (HLA, 3) and (PippN=P(C4H8))2DMC, (HLB, 10), where Pipp = para-isopropylphenyl, DMC = 3,6-dimethylcarbazole, is 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(CH2SiMe3)3(DMAP)2, 4, as well as Lu(CH2SiMe3)3(THF)2. In the case of 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 PMe2 groups generated the complex (LA-ΚThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Bis(pyrazolyl)carbazole as a Versatile Ligand for Supporting Lutetium Alkyl and Hydride Complexes

Two derivatives of a new bis­(pyrazolyl)­carbazole pincer ligand H­(Cz­Pz^R), R = ^<i>i</i>Pr and Me, and their syntheses are reported. Lutetium dialkyl complexes of the ligand (CzPz^R)­Lu­(CH₂­SiMe₃)₂, R = ^<i>i</i>Pr and Me, have been prepared and found to exhibit high thermal stability in solution. These organolutetium compounds are Lewis base free, and the solid-state structure of (CzPz^<i>i</i>Pr)­Lu­(CH₂­SiMe₃)₂ revealed that the complex is monomeric with a trigonal-bipyramidal geometry. Hydrogenolysis of (CzPz^<i>i</i>Pr)­Lu­(CH₂­SiMe₃)₂ afforded a trimetallic lutetium hydride complex that possesses five bridging hydride ligands. Notably, intramolecular C–H bond activation of the CzPz^<i>i</i>Pr ligand was found to occur during the formation of this latter hydride complex, with metalation of a pyrazole carbon atom