Comparative Measure of the Electronic Influence of Highly Substituted Aryl Isocyanides
- 20 February 2015
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 54 (6), 2936-2944
- https://doi.org/10.1021/ic5030845
Abstract
To assess the relative electronic influence of highly substituted aryl isocyanides on transition metal centers, a series of C4v-symmetric Cr(CNR)(CO)5 complexes featuring various alkyl, aryl, and m-terphenyl substituents have been prepared. A correlation between carbonyl-ligand (13)C{(1)H} NMR chemical shift (δCO) and calculated Cotton-Kraihanzel (C-K) force constant (kCO) is presented for these complexes to determine the relative changes in isocyanide σ-donor/π-acid ratio as a function of substituent identity and pattern. For nonfluorinated aryl isocyanides possessing alkyl or aryl substitution, minimal variation in effective σ-donor/π-acid ratio is observed over the series. In addition, aryl isocyanides featuring strongly electron-releasing substituents display an electronic influence that nearly matches that of nonfluorinated alkyl isocyanides. Lower σ-donor/π-acid ratios are displayed by polyfluorinated aryl isocyanide ligands. However, the degree of this attenuation relative to nonfluorinated aryl isocyanides is not substantial and significantly higher σ-donor/π-acid ratios than CO are observed in all cases. Substituent patterns for polyfluorinated aryl isocyanides are identified that give rise to low relative σ-donor/π-acid ratios but offer synthetic convenience for coordination chemistry applications. In order to expand the range of available substitution patterns for comparison, the syntheses of the new m-terphenyl isocyanides CNAr(Tripp2), CNp-MeAr(Mes2), CNp-MeAr(DArF2), and CNp-FAr(DArF2) are also reported (Ar(Tripp2) = 2,6-(2,4,6-(i-Pr)3C6H2)2C6H3); p-MeAr(Mes2) = 2,6-(2,4,6-Me3C6H2)2-4-Me-C6H2); p-MeAr(DArF2) = 2,6-(3,5-(CF3)2C6H3)2-4-Me-C6H2); p-FAr(DArF2) = 2,6-(3,5-(CF3)2C6H3)2-4-F-C6H2).Funding Information
- National Science Foundation
- U.S. Department of Energy (DE-SC0008058)
- Camille and Henry Dreyfus Foundation
This publication has 74 references indexed in Scilit:
- Zwitterionic Stabilization of a Reactive Cobalt Tris‐Isocyanide Monoanion by Cation CoordinationAngewandte Chemie, 2012
- Recent developments in transition metal diaryl chemistryDalton Transactions, 2010
- OLEX2: a complete structure solution, refinement and analysis programJournal of Applied Crystallography, 2009
- A short history of SHELXActa Crystallographica Section A Foundations of Crystallography, 2007
- Design and Synthesis of Isocyanide Ligands for Catalysis: Application to Rh‐Catalyzed Hydrosilylation of KetonesChemistry – An Asian Journal, 2007
- First Paramagnetic Zerovalent Transition Metal Isocyanides. Syntheses, Structural Characterizations, and Magnetic Properties of Novel Low-Valent Isocyanide Complexes of Vanadium1Journal of the American Chemical Society, 2000
- Transition metal complexes and cycloaddition products of pentafluorophenyl isocyanideJournal of Fluorine Chemistry, 1998
- Reaction of aromatic isocyanides with triethylamine: a new method for the synthesis of indole betainesMendeleev Communications, 1998
- Vibrational Spectra and Bonding in Metal Carbonyls. I. Infrared Spectra of Phosphine-substituted Group VI Carbonyls in the CO Stretching RegionJournal of the American Chemical Society, 1962
- The Donor-Acceptor Properties of Isonitriles as Estimated by Infrared StudyJournal of the American Chemical Society, 1961