109434-14-2Relevant academic research and scientific papers
13C and 17O NMR and IR spectroscopic study of a series of carbonyl(4-substituted pyridine)(meso-tetraphenylporphinato)iron(II) complexes. Correlations between NMR chemical shifts and IR stretching frequencies of the carbonyl ligand and taft parameters of the pyridine substituent
Box, James W.,Gray, Gary M.
, p. 2774 - 2778 (2008/10/08)
The results of a 13C and 17O NMR and IR spectroscopic study of a series of carbonyl(4-substituted pyridine) (meso-tetraphenylporphinato)iron(II) (Fe(TPP)(CO)(py-4-X)) complexes are presented. Good to excellent linear correlations between the 13C and 17O NMR chemical shifts and the IR stretching frequencies of the carbonyl ligand are observed as the pyridine substituent is varied. Good to excellent linear correlations are also observed between these NMR chemical shifts and IR stretching frequencies and the NMR chemical shifts and IR stretching force constants for the trans carbonyls of a series of cis-Mo(CO)4(py-4-X)2 complexes as the pyridine substituent is varied. The relationship between the donor ability of the pyridine ligands and the 13C and 17O NMR chemical shifts and IR stretching frequencies of the carbonyl ligands in the Fe(TPP)(CO)(py-4-X) complexes has been quantitated by fitting the spectroscopic data to the single and the dual Taft substituent parameters of the pyridine substituent. Good to excellent correlations are observed. The upfield shift in the 13C NMR resonance of the carbonyl ligand as the electron-donor ability of the pyridine increases is unique. This has been rationalized by using the Buchner and Schenk description of metal carbonyl 13C NMR chemical shifts.
