o-Alkyl-substituted aromatic phosphanes for hydroformylation studies: synthesis, spectroscopic characterization and ab initio investigations

• Published in: Journal of molecular catalysis. A, Chemical Vol. 200; no. 1; pp. 69 - 79
• Main Authors: Riihimäki, Helena, Suomalainen, Pekka, Reinius, Heidi K, Suutari, Johanna, Jääskeläinen, Sirpa, Krause, A.O.I, Pakkanen, Tapani A, Pursiainen, Jouni T
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2003; Elsevier
• Subjects: Ab initio calculations; Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Hydroformylation; NMR spectroscopy; o-Alkyl-substituents; Phosphane ligands; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; o-Alkyl-substituents; Ab initio calculations; NMR spectroscopy; Phosphane ligands; Hydroformylation; Tertiary phosphine; Ab initio method; Organic ligand; NMR spectrometry; Transition metal Complexes; Phosphorus Organic compounds; Characterization; Synthesis; Rhodium Complexes; Platinoid Complexes
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(03)00022-0

In earlier hydroformylation studies modification of the rhodium catalyst with o-methyl-substituted or o-ethyl-substituted phosphane ligands have increased regioselectivity to branched aldehydes. The promising results achieved created a need for further studies. Hence, a wider group of o-substituted arylphosphane ligands, e.g. (2-cyclohexylphenyl)diphenylphosphane, (2-isopropylphenyl)diphenylphosphane, (2-methylnaphthyl)diphenylphosphane, (2,5-dimethylphenyl)diphenylphosphane and (2-phenylphenyl)diphenylphosphane were synthesized and tested in rhodium-catalyzed hydroformylation to support the previous findings. Characterization of the ligands was made by NMR spectroscopy ( 1 H , 31 P { 1 H }, 13 C { 1 H }, HSQC, COSY-90 and COLOC). Additional parameters for evaluation of the stereoelectronic properties of the ligands were provided by quantum mechanical calculations and by synthesizing Rh(acac)(CO)(PR 3) complexes. In the rhodium-catalyzed hydroformylation of propene and 1-hexene the ligands increased the formation of branched aldehydes compared to triphenylphosphane. Additionally the increasing size of the o-alkyl-substituent was found to effect favorably to the iso-selectivity.