PubMed · 4057499
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P Wald, L Goldfrank. Cyanide intoxication.. https://pubmed.ncbi.nlm.nih.gov/4057499/
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We have recorded the powder EPR-spectra of some near octahedral iron(III) complexes with tridentate ligands donors and analysed their spectra with simple ligand field analysis and for some cases with the angular overlap model (AOM). We have determined the electron praramagnetic resonance (EPR) characteristic of bis 1,4,7-triazacyclonane iron(III)chloride at 4 K and found that it was similar to the characteristics of the so-called 'highly anisotropic low spin' complexes. We have recorded the powder spectra of bis (2,6-bis(benzimidazoly-2-yl)pyridine) iron(III) perchlorate and made an AOM-analyses of the structural similar complex bis-(2,6 (N-carbamoyl)-pyridine) iron(III). With a combination of ligand field analyses and AOM, we could determine the pi-donor properties of these ligands. The same approach have been used to determine the pi-donor properties of the hydroperoxo ligand. Finally we have recorded the powder EPR-spectrum of [Fe(CN)6]3- doped in K3[Co(CN)6] and [Co(NH3)6][Co(CN)6] at 4 and 100 K and in water at 4 K. The spectra are interpreted as the effect of a dynamic Jahn-Teller distortion.
Regioselective functionalization of 2,4,5,6-tetrachloro-1, 3-dicyanobenzene (TCDCB) by nucleophilic substitution of the chlorine at C(4) with L-Ala, L-Phe or L-Pro, followed by amide-bond formation to lipophilic amines containing strong pi-donor group, and by final introduction of the spacer 3-aminopropyltriethoxysilyl (APTES), provided a number of new brush-type chiral selectors in the form of 1-2:1 mixture of 2,4 and 4,6-di(alkyl)amino regioisomers (8/9, 10/11, 12/13, 14/15, 20/21, 23/24). Linking these to silica gel (Nucleosil 100-5) gave new chiral stationary phases for HPLC columns (CSP I-CSP VI). Being strong pi-basic selectors, most of these columns exhibited good resolution properties for pi-acid test racemates (TR 1-TR 9), specifically rac 3, 5-dinitrobenzoyl-alpha-amino acid isopropyl-esters (DNB-AA). CSP V [1,3-dicyano-2,5(5,6)-dichloro-6(2)-(gamma'-silica bound propylamino)-4-N-¿[N-butyl]-N'-[(1R)-cyclohexylethyl]-N'-[napht hylmet hyl]acetamido¿-aminobenzene] and particularly the dipeptide-containing CSP VI [2,5(5,6)-dichloro-6(2)-(gamma'-silica bound propylamino)-4-N-(3', 5'-dimethylanilido)-L-alanyl-L-prolyl-aminobenzene] proved to have the highest efficiency, comparable with the best commercial brush-type columns with pi-donor properties. Further evidence revealed that multiple hydrogen bonding via the amide group in the chiral environment and pi-pi interaction play a major role in chiral recognition, whereas steric perturbations via nonbonding VDW interactions contribute substantially only to the resolution of CSP III [2,5(5,6)-dichloro-6(2)-(gamma'-silica bound propylamino)-4-N-(cyclohexylamido)-L-alanyl-aminobenzene]. This contribution is minor for the other CSPs.