An infrared and phosphorus-31 nuclear magnetic resonance spectroscopic study of some square planar rhodium (I) complexes

Author

Celeste Reneé Daffron

Date of Award

12-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Clifton Woods

Committee Members

Dave Abbott, Richard Hutchings, Don Womack

Abstract

The electronic environment of rhodium in some square planar complexes has been monitored using both infrared spectroscopy and nuclear magnetic resonance spectroscopy. Efforts have been made to determine the importance of σ and π contributions of the ligands to the observed variations in spectral parameters. The pK_a's of some substituted pyridines have been used as a measure of the σ donor ability of these ligands toward Rh in trans-[Rh(CO)L(PPh₃)₂]PF₆ complexes. It has been found that the pK_a is related linearly to the carbonyl stretching frequency for some pyridine complexes. In trans-[Rh(CO)A(PPh₃)₂] complexes (A = anionic ligand), no obvious correlation was observed between ν(C≡O) and a parameter called the sigma electronegativity of A (χ_A(σ)).

Rhodium-phosphorus coupling constants have been measured for the complexes. A meaningful correlation between J_Rh-P and χ_A(σ) was not observed; however, for most pyridines a general increase in J_Rh-P is observed with increasing pK_a. It has also been observed that J_Rh-P varies by a constant amount as the pyridines or the anionic ligands are varied in these square planar complexes.

Recommended Citation

Daffron, Celeste Reneé, "An infrared and phosphorus-31 nuclear magnetic resonance spectroscopic study of some square planar rhodium (I) complexes. " Master's Thesis, University of Tennessee, 1981.
https://trace.tennessee.edu/utk_gradthes/15162