Synthesis, Coordination to Rh(I), and Hydroformylation Catalysis of New β-Aminophosphines Bearing a Dangling Nitrogen Group: An Unusual Inversion of a Rh-Coordinated P Center - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2002

Synthesis, Coordination to Rh(I), and Hydroformylation Catalysis of New β-Aminophosphines Bearing a Dangling Nitrogen Group: An Unusual Inversion of a Rh-Coordinated P Center

Résumé

Variants of the β-aminophosphine L1 [Ph2PCH2CH(Ph)NHPh] containing additional nitrogen donor functions have been prepared. These functions are branched off the C atom adjacent to the P atom, or the P atom itself. Ligand [Ph2PCH(o-C6H4NMe2)CH(Ph)NHPh] has been obtained as a mixture of two diastereomers L3A and L3B by lithiation of L2 [Ph2PCH2(o-C6H4NMe2)] with n-BuLi followed by PhCHNPh addition and hydrolysis. The diastereomers have been separated by fractional crystallization from ethanol. Ligand Et2NCH2P(Ph)CH2CH(Ph)NHPh has been obtained as a mixture of two diastereomers L5A and L5B starting with P−Ph reductive cleavage of L1 by lithium and subsequent hydrolysis to give PhP(H)CH2CH(Ph)NHPh (mixture of two diastereomers L4A and L4B). The latter reacts with diethylamine and formaldehyde to afford the L5 diastereomeric mixture. Complexes RhCl(CO)(L) (L = L3A, 1A; L3B, 1B; L5A/B, 2A/B) were obtained by reaction of [RhCl(CO)2]2 and the appropriate ligand or ligand mixture. Complexes 1A, 1B, and 2A have been isolated in pure form and characterized by classical techniques and by single-crystal X-ray diffraction. All structures exhibit a bidentate κ-P,κ-N(NHPh) mode similar to the complex containing L1. While complexes 1A or 1B are stable in CDCl3 solution, complex 2A slowly converts to its diastereomer 2B. This unexpected epimerization appears to take place by inversion at the Rh-coordinated P center, an apparently unprecedented phenomenon. A mechanism based on a reversible P−C bond oxidative addition is proposed. The influence of the pendant nitrogen function of the diaminophosphines L3A and L5A/B on the rhodium catalytic activity in styrene hydroformylation has been examined and compared to that of the aminophosphines L1 or L2. The observed trends are related to the basicity of the dangling amine function and to its proximity to the metal center.
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hal-03284120 , version 1 (20-07-2021)

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Jacques Andrieu, Philippe Richard, Jean-Michel Camus, Rinaldo Poli. Synthesis, Coordination to Rh(I), and Hydroformylation Catalysis of New β-Aminophosphines Bearing a Dangling Nitrogen Group: An Unusual Inversion of a Rh-Coordinated P Center. Inorganic Chemistry, 2002, 41 (15), pp.3876-3885. ⟨10.1021/ic011035i⟩. ⟨hal-03284120⟩
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