Samuel R. Lee^a, Natchayatorn Keawkla^b, R. Noah Sladek^a, Nattamai Bhuvanesh^a, Panida Surawatanawong^b*, and Oleg V. Ozerov^a

^aDepartment of Chemistry, Texas A&M University, College Station, Texas 77842, United States

^bDepartment of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

Protolysis of AlMe₃ or AlEt₃ with 2-diisopropylphosphinopyrrole (1) resulted in alane/bis(phosphine) pincer ligands containing two flanking phosphines and a central Al-Me (2-Me), Al-Et (2-Et) unit.  Reactions of 2-Me with [(COD)MI]₂ (COD = 1,5-cyclooctadiene; M = Rh or Ir) in the presence of pyridine produced pincer complexes (3-Rh-I and 3-Ir-I) with M supported by the PAlP tridentate ligand, and pyridine, methyl, and iodide as monodentate ligands for Al or M.  The analogous reaction of 2-Et with [(COD)MI]₂ and pyridine resulted in the formation of the analogous compounds 4-Rh-I and 4-Ir-I with hydride in place of methyl.  DFT calculations were used to analyze the thermodynamic preferences for the positioning of pyridine, methyl or hydride, and the halide (chloride or iodide) on M vs Al.  Cobalt was included with Rh and Ir among M for the purposes of DFT calculations.  Theoretical studies suggested that different isomers are preferred for the iodide complexes (M-I and Al-Py) than for the chloride ones (M-py and Al-Cl, previously reported for Rh and Ir).  X-ray structural study of 3-Rh-I and analysis of the ¹H NMR data of the Rh and Ir compounds in benzene corroborated these predictions.

Reference: Lee, S. R.;  Keawkla, N.;  Sladek, R. N.;  Bhuvanesh, N.;  Surawatanawong,* P.; Ozerov,* O. V. Organometallics 2025, 44, 347-353. https://pubs.acs.org/doi/abs/10.1021/acs.organomet.4c00490