Two pairs of geometrical isomers, cis- and trans-[RhCl2L2]+ [L = 1,3-bis(dimethylphosphino)propane or 1,2-bis(dimethylphosphino)ethane], have been synthesized and their structures and spectroscopic properties investigated. The previous characterization of the dmpe complexes made by other workers was found to be erroneous. A convenient method of preparation and separation of the complexes into isomers has been found. The geometrical structures of the isomers have been confirmed by 1H, 13C and 31P NMR spectroscopy and by single-crystal X-ray structure determinations. The Rh-Cl bond lengths in the cis complexes are considerably longer than those in the corresponding trans isomers, and the Rh-P bonds trans to Cl in the cis isomers are relatively shorter than those of mutually trans phosphine ligands in both the cis- and trans-isomers, exhibiting a strong trans influence of the dimethylphosphino group. The 1H, 13C and 31P NMR spectra of the complexes were found to be consistent with the structures found by single-crystal X-ray analyses, and the chemical shifts (δp) and coupling constants [1J(RhP) and 2J(PP)] correspond well with the structural parameters (Rh-P bond length and P-Rh-P angle). The electronic spectra and isomerization reactions of the complexes were also determined.
|Number of pages||8|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - Dec 1 1995|
ASJC Scopus subject areas