SOLVENT-DEPENDENT DEUTERON NMR-SPECTRA AND SOLVATOCHROMISM IN LIGAND-FIELD ABSORPTION-BANDS FOR TRANS-[CRX2(3,2,3-TET)]+ - CORRELATION WITH THE ANGULAR OVERLAP MODEL PARAMETRIZATION

The solvent-dependent deuteron nuclear magnetic resonance (1 2H NMR) and ligand field absorption spectra of irons-[CrX2-(3,2,3-tet)]+, where 3,2,3-tet denotes 1,10-diamino-4,7-diazadecane (NH2CH2CH2CH2NHCD2CD2NHCH2CH2CH2NH2) and where axial ligands X are F−, Cl−, Br−, NCS−, CN−, OH−, H2O, and NH3, were studied. These solvent dependencies were correlated with Gutmann‧s acceptor numbers for solvents. The ligand field bands were analyzed by using the angular overlap model, and it was found that the solvatochromism could be ascribed to variations of the metal-ligand σ-bond interactions (expressed by the eσ(X) and eσ(N) AOM parameter values) due to the selective solvation toward the axial ligands. A linear relation between the 2H NMR shifts and the AOM eσ parameters provides a direct probe to estimate the AOM eσ parameter values. A notable ligand field variability was found and substantiated the interligand cooperative effect or cis electronic effect. This fact does not necessarily result cither in rigorous parameter transferability from complex to complex or in additivity for mixed-ligand complexes. © 1990, American Chemical Society. All rights reserved.