Spectroscopic, Structural and DFT Study of the Responses of Carbonylmetal Crown Ether Complexes to Alkali Metal Cations

Stephenson, G. Richard, Anson, Christopher E., Creaser, Colin S. and Daul, Claude A. (2011) Spectroscopic, Structural and DFT Study of the Responses of Carbonylmetal Crown Ether Complexes to Alkali Metal Cations. European Journal of Inorganic Chemistry, 2011 (13). pp. 2086-2097. ISSN 1434-1948

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Abstract

FTIR spectra of tricarbonyl(eta(6)-benzo-15-crown-5)chromium(0) (1) in the presence of lithium, sodium and potassium perchlorate salts in methanol show different responses in the Cr-CO vibrational region of the spectrum. Data from the symmetric (nu(sym)) and antisymmetric (nu(asym)) Cr-CO vibrational stretching modes have been analysed by principal component analysis (PCA) to generate a factor score plot that provides a visual representation of these differential responses. X-ray crystallographic data for the sodium perchlorate complex 1 center dot Na+ and dimensions from DFT-derived structures of 1 center dot Li+, 1 center dot Na+ and 1 center dot K+ indicate that binding M+ in the crown causes electron density and structural changes in the [O(4)-C(9)-C(4)-O(8)]Cr-C(1)=O(1) sections of 1, which vary depending on the nature of the cation. This suggests a mode of action in which Li+ associates with a more compact O(4)C( 9)-C(4)-O(8), while Na+ and K+ differ crucially in the extent of sigma and pi contributions to their effect on nu(sym) and nu(asym). A comparison of the FTIR data from 1, tricarbonyl(eta(6)-1-phenyl-1-aza-15-crown-5)chromium(0) (2) and tricarbonyl(eta(6)-2-phenyl-15-crown-5)chromium(0) (3) with a wider range of cations (NH4+, Li+, Na+, K+, Rb+, Cs+, Mg2+, Ba2+) and anions (AcO-, BPh4-, Br-, C1O(4)(-), I-, SCN-), showed that 1 and 3 both responded significantly to the different metal cations, but 2 did not. The relative cation differentiation of 1, 2 and 3 was measured using the parameter Delta(R(cation)), and ratios of Delta(N(cation)) values [calculated from Delta(R(cation))] distinguished different effects in the FTIR spectra of 1 and 3 for different pairs of cations.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 12 Jul 2011 13:37
Last Modified: 21 Apr 2020 16:53
URI: https://ueaeprints.uea.ac.uk/id/eprint/33551
DOI: 10.1002/ejic.201001274

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