Conformational studies of chelated sulphur- and selenium-containing ligands by nuclear magnetic resonance. Part III. Band-shape fitting studies for complexes of 1,2-bis(isopropylseleno)ethane with palladium(II) halides and with chromium, molybdenum, and tungsten carbonyl complexes

Abstract

Band-shape fitting studies have been made for the ¹H n.m.r. spectra of complexes of the deuteriated analogue of the chelating ligand 1,2-bis(isopropylseleno)ethane with palladium(II) halides and with chromium, molybdenum, and tungsten carbonyl complexes. These studies show conclusively that the coalescence phenomenon observed in the temperature-dependent n.m.r. spectra results from inversion of configuration about the ligand atoms and not from reversal of the chelate ring. Detailed analysis of the spectra of the chelate-ring methylene protons and thermodynamic parameters for the inversion process are reported.