Computational insight into 103Rh chemical shift-structure correlations in rhodium bis(phosphine) complexes

Manuel A Ortuno Maqueda, Ludovic Castro, Michael Bühl

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

103Rh NMR chemical shifts have been computed at the GIAO-B3LYP level of density functional theory (DFT) for a number of [Rh(COD)(PP)] + complexes [COD = 1,5-cyclooctadiene, PP = chelating bis(phosphine) including bis(dimethylphosphino)ethane (dmpe), bis(diphenylphosphino)ethane (dmpe), MeDUPHOS, DIOP, BINAP, and others]. Structures have been optimized using PBE0 and M06 functionals in the gas phase, in a continuum modeling the solvent, and with [PF6]- counteranion included explicitly. Observed trends in δ(103Rh) are well reproduced for pristine PBE0-optimized cations in the gas phase or for ion pairs optimized in a continuum with M06. While there is no overall trend between computed δ(103Rh) values and complex stabilities (evaluated through isodesmic ligand exchange reactions), there is a linear relationship between the 103Rh chemical shifts and the mean Rh-P bond distances. This relationship appears to be remarkably general, encompassing various chelating ring sizes and substituents at P, including remote electron-donating and -withdrawing substituents that are characterized through their Hammett constants. The combination of 103Rh NMR and DFT computations emerges as a useful tool for structure elucidation of Rh-phosphine complexes.

Original languageEnglish (US)
Pages (from-to)6437-6444
Number of pages8
JournalOrganometallics
Volume32
Issue number21
DOIs
StatePublished - Nov 11 2013

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