Author(s) Varela-Izquierdo, V.; Geer, A.M.; de Bruin, B.; López, J.A.; Ciriano, M.A.; Tejel, C.
Journal Chemistry
Date Published 2019 Dec 10
Abstract

The feasibility of oxidative addition of the P-H bond of PHPh to a series of rhodium complexes to give mononuclear hydrido-phosphanido complexes has been analyzed. Three main scenarios have been found depending on the nature of the L ligand added to [Rh(Tp)(C H )(PHPh )] (Tp= hydridotris(pyrazolyl)borate): i) clean and quantitative reactions to terminal hydrido-phosphanido complexes [RhTp(H)(PPh )(L)] (L=PMe , PMe Ph and PHPh ), ii) equilibria between Rh and Rh species: [RhTp(H)(PPh )(L)]⇄[RhTp(PHPh )(L)] (L=PMePh , PPh ) and iii) a simple ethylene replacement to give the rhodium(I) complexes [Rh(κ -Tp)(L)(PHPh )] (L=NHCs-type ligands). The position of the P-H oxidative addition-reductive elimination equilibrium is mainly determined by sterics influencing the entropy contribution of the reaction. When ethylene was used as a ligand, the unique rhodaphosphacyclobutane complex [Rh(Tp)(η -Et)(κ -CH CH PPh )] was obtained. DFT calculations revealed that the reaction proceeds through the rate limiting oxidative addition of the P-H bond, followed by a low-barrier sequence of reaction steps involving ethylene insertion into the Rh-H and Rh-P bonds. In addition, oxidative addition of the P-H bond in OPHPh to [Rh(Tp)(C H )(PHPh )] gave the related hydride complex [RhTp(H)(PHPh )(POPh )], but ethyl complexes resulted from hydride insertion into the Rh-ethylene bond in the reaction with [Rh(Tp)(C H ) ].

DOI 10.1002/chem.201903981
ISSN 1521-3765
Citation Varela-Izquierdo V, Geer AM, de Bruin B, López JA, Ciriano MA, Tejel C. Rhodium Complexes in P-H Bond Activation Reactions. Chemistry. 2019;25(69):15915-15928.

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