Infrared spectra of metal anthranilates

The infrared spectra of the sodium salts and the Mn(II), Co(II), Ni(II), Cu(II) and Zn(Il) chelates of anthranilic acid and 5-methyl-, 5-chloro-, 5-bromo-and 5-iodo-anthranilic acid are discussed. ¹⁵N-Labelling of sodium anthranilate and the complexes of anthranilic acid provides assignments of the ligand vibrations involving the amino group. The metal-ligand stretching frequencies (vM-N and vM-O) are assigned by observing the effects on the spectra caused by ¹⁵N-labelling, metal ion substitution and ligand substitution. The vCu-O bands are split by tetragonal distortion in the Cu(II) complex which involves elongation of the axial Cu~O bonds. The metal ion dependence of vM-N and vM-O parallels the Irving-Williams stability sequence. The ligand substituents shift vM-O in accordance with their inductive effects while vM-N exhibits a substituent dependence which is roughly the opposite of that shown by vM-O.     

The infrared spectra (600-140 cm−1 of the imidazole,pyrazine and pyrimidine adducts of cobalt(II), nickel(II) and zinc(II) acetylacetonates

Summary The complexes M(acac)₂(imidazole)₂ (M = Co or NO and [M(acac)₂B]_n (M = Co, Ni or Zn; B = pyrazine or pyrimidine) have been prepared and their i.r. spectra determined over the 600–140 cm^–1. range. The metal-oxygen and metal-nitrogen stretching frequencies, (M-O) and v(M-N), are assigned on the basis of the band shifts induced by deuteriation of the adducted base and by substitution of the metal ion. Three or fourv(M-O) bands are observed within the 600-200 cm^–1 range. The twov(M-O) bands of higher frequency are considered to the coupled with internal ligand modes. TwovM-N) bands are observed within the 280–170 cm^–1. range. The metal-ligand stretching frequencies are in good agreement with the values previously established for these vibrations in the [M(imidazole)₆]²⁺ and Ni(acac)₂(pyridine)₂ complexes.     

Comparison of capillary electrophoresis with traditional methods to analyse bovine whey proteins

The separation of the four major whey proteins by sodium dodecyl sulphate (SDS)-capillary gel electrophoresis (CGE) is described. Whilst commercially purified whey proteins could be analysed using the recommended protocol, the more complex nature of an acid whey and a reconstituted whey protein concentrate (WPC) powder necessitated considerable refinement of the CGE sample buffer. Individual whey proteins in the acid whey and WPC samples were then also separated and quantitated using capillary zone electrophoresis, polyacrylamide gel electrophoresis (PAGE) and HPLC methods and the results were compared. The values obtained for -lactalbumin (-Lac) and β-lactoglobulin (β-Lg) were consistent throughout the various methods, although size-exclusion HPLC, SDS-PAGE and SDS-CGE could not separate the two β-Lg variants or the glycosylated form of -Lac from the β-Lg. There was considerable variation in the values for the bovine serum albumin and immunoglobulin determined by the different methods and it was concluded that none of the methods could satisfactorily quantitate all four whey proteins.     

A theoretical interpretation of isotope effects in mixtures of light and heavy water—II

Solvent isotope effects for H₂O---D₂O mixtures and for ionic hydration equilibria in such mixtures can be calculated from the structure difference between D₂O and H₂O and that between HDO and H₂O and the relative amounts of the three waters. The behavior of acids in H₂O---D₂O mixtures is considered in detail. Dissociation constants of acetic acid are calculated over the complete range of deuterium concentrations and found to agree with the experimentally determined ones. The Gross equation for the dependence of isotope effect on mole fraction of deuterium for acid-catalyzed reaction of substrates S proceeding via SL⁺ transition states (L=H or D) is derived from first principles.     

Infrared spectra of bis(aniline) and bis (p-toluidine) metal(II) isothiocyanate complexes

The infrared spectra of eight complexes of general formula [ML₂(NCS)₂] (M = Co, Ni, Cu, Zn; L = aniline or p-toluidine) have been determined over the range 4000–4150 cm^?1. Colour, magnetic moments and IR spectra are consistent with polymeric octahedral coordination in the Co(II) and Ni(II) complexes and polymeric tetragonal coordination in the Cu(II) complexes, while the Zn(II) complexes are assigned polymeric octahedral (L = aniline) and tetrahedral (L = p-toluidine) structure on the basis of their IR spectra. Independent ¹⁵N-labelling of the nitrogen atoms of the amino and isothiocyanate groups yields assignments for the internal vibrations of both groups and enables the metal-amine and metal—isothiocyanate stretching vibrations (vM-NH₂ and vM-NCS) to be distinguished. Both vM-NH₂ and vM-NCS are metal ion dependent in the Irving-Williams sequence (Co < Ni < Cu > Zn) expected from their proposed structures while the vN-H and vN-CS vibrations are inversely related to the masses of the coordinated metal ions.     

Infrared Spectra of α-Thenoyl-trifluoroacetonates of Metal Ions of the First Transition Series

The IR. spectra of α-thenoyl-trifluoroacetone (HTTA) and seventeen of its chelates with metal(II) and -(III) ions of the first transition series have been determined. Three series of complexes are represented: the anhydrous metal(II) species, [M(TTA)₂]_n (M ? Ca, Mn, Co, Ni, Cu, Zn); metal(II) dihydrates, [M(TTA)₂(H₂O)₂] (M ? Mn, Fe, Co, Ni, Zn); and the metal(III) chelates, [M(TTA)₃] (M ? Sc, V, Cr, Mn, Fe, Ga). For each metal(II) complex, the spectra of the anhydrous and hydrated compounds are practically identical, suggesting that the anhydrous complexes have the polynuclear octahedral structure established for the corresponding acetylacetonates. Magnetic moment determinations reveal that complexes of the 3d⁴?3d⁷ ions all have spin-free configuration. Several vibrational bands with frequencies < 700 cm^?1 are found to exhibit a frequency variation with d-orbital population which is consistent with the order of crystal field stabilization energies and hence with their assignment as coupled metal-oxygen stretching modes. Unique features of the spectra of [Cu(TTA)₂] and [Mn(TTA)₃] are ascribed to structural differences arising from Jahn-Teller distortion. Tentative assignments for the majority of the ligand vibrations are given.     

A Spectroscopic Study of Alkylamine Complexes of Copper(II) Succinimide

Abstract

The vibrational and electronic spectra of eleven complexes of copper(II) succinimide [CuSu²Am₂] (Su = succinimide ion; Am = variously substituted primary aliphatic amines) show that metal-imide co-ordination occurs through the imide nitrogen atom. The electronic effects of the amine substituents on the carbonyl stretching frequencies and on the electronic spectra are used to infer the probable mechanism of metal-imide bonding.