Reversible heterolytic CH cleavage by intramolecular CH activation at diazabutadiene ligands at iridium
摘要:
Reactions between [(CpIrCl2)-Ir-*](2) and diaryl-substituted diazabutadienes (dab) ArN=CR'-CR'=NAr (R' = H: Ar = 4-MeC6-H-4, 2,6-Me2C6H3, 2,6-(i) Pr2C6H3; R' = Me: Ar = 4-MeC6H4) proceed straightforwardly to give the dab complexes (CpIr)-Ir-*(dab)Cl+Cl-. Sterically more encumbered dab ligands (R' = Me: Ar = 2,6-Me2C6H3, 2,6-(i) Pr2C6H3, 2,4,6-Me2C6H3) instead give products Cp-* IrClCH2C(=NHAr)CMe=N(Ar)Cl-+(-) in which the dab ligand has undergone C-H activation at one of methyl groups of the dab bridge. The C-H cleavage reaction is reversible in the sense that thermally, the cyclometalated Ir complex decomposes to regenerate the free ligand. (C) 2002 Elsevier Science B.V. All rights reserved.
Reversible heterolytic CH cleavage by intramolecular CH activation at diazabutadiene ligands at iridium
摘要:
Reactions between [(CpIrCl2)-Ir-*](2) and diaryl-substituted diazabutadienes (dab) ArN=CR'-CR'=NAr (R' = H: Ar = 4-MeC6-H-4, 2,6-Me2C6H3, 2,6-(i) Pr2C6H3; R' = Me: Ar = 4-MeC6H4) proceed straightforwardly to give the dab complexes (CpIr)-Ir-*(dab)Cl+Cl-. Sterically more encumbered dab ligands (R' = Me: Ar = 2,6-Me2C6H3, 2,6-(i) Pr2C6H3, 2,4,6-Me2C6H3) instead give products Cp-* IrClCH2C(=NHAr)CMe=N(Ar)Cl-+(-) in which the dab ligand has undergone C-H activation at one of methyl groups of the dab bridge. The C-H cleavage reaction is reversible in the sense that thermally, the cyclometalated Ir complex decomposes to regenerate the free ligand. (C) 2002 Elsevier Science B.V. All rights reserved.