| Abstract
| - A range of rhodium(I) and iridium(I) complexes containing bidentate phosphine−pyrazolyl ligands ofgeneral formulas [M(R2PyP)(COD)]BPh4 (R = Me, iPr, Ph, M = Ir, 3b−3d and M = Rh, 4b−4d),[Ir(R2PyP)(CO)2]BPh4 (R = Me, iPr, 5b,5c), and [M(R2PyP)(CO)Cl] (R = Me, iPr, Ph, M = Ir, 6b−6dand M = Rh, 7b−7d) were successfully synthesized. A number of these complexes and their analogueswith unsubstituted ligands are extremely active as catalysts for the intramolecular hydroamination ofalkynes. The air-stable cationic iridium complexes containing 1,5-cyclooctadiene, COD, as co-ligands,[Ir(R2PyP)(COD)]BPh4 (R = H, Me, iPr, and Ph, 3a−3d), are efficient as catalysts for the cyclization of4-pentyn-1-amine (8) to 2-methyl-1-pyrroline (9) with the turnover rate at 50% conversion (Nt) of up to3100 h-1, at 60 °C. The cationic iridium complexes containing carbonyl co-ligands, [Ir(R2PyP)(CO)2]BPh4 (R = H, Me, iPr, 5a−5c), are moderately effective in catalyzing this reaction, and the neutralcomplexes [M(R2PyP)(CO)Cl] (M = Ir, 6a Ir, 7a) are ineffective. Generally, an increase in steric bulkof the substituent R near the nitrogen donor leads to an improvement in catalytic performance of theresulting metal complexes.
- Cationic iridium complexes with phosphine−pyrazolyl donor ligands and a COD co-ligand are among the most efficient catalysts reported in the literature to date for the intramolecular hydroamination of alkynes. These complexes also have long catalytic lifetimes and are effective even at ambient temperature.
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