Abstract
103RhNMR chemical shifts have been computed at the GIAO-B3LYP level of density functional theory (DFT) for a number of [Rh(COD)(P∩P)]+ complexes [COD = 1,5-cyclooctadiene, P∩P = 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 language | English |
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Pages (from-to) | 6437-6444 |
Number of pages | 8 |
Journal | Organometallics |
Volume | 32 |
Issue number | 21 |
Early online date | 4 Oct 2013 |
DOIs | |
Publication status | Published - 11 Nov 2013 |
Keywords
- Density-functional theory
- Transition-metal-complexes
- Molecular orbital methods
- NMR spectroscopy
- Basis sets
- Organometallic complexes
- Noncovalent interactions
- Diolefin complexes
- Shielding tensors
- Olefin complexes