Takao Moriwaki

The metal complexes of amino acids and their N-substituted derivatives—VII. The i.r. spectra and normal coordinate analyses of bivalent metal complexes with N-methylglycine and N-phenylglycine

Twelve complexes of bivalent metals with N-methylglycine (sarcosine) and N-phenylglycine have been prepared over wide pH ranges and characterized by means of i.r. powder diffuse reflection, electronic spectra and magnetic susceptibility. These complexes are classified into two types, either with or without chloride ions, from elemental analyses: the former type (A) consists of ML2·nH2O (M = Co, Ni, Cu, Zn for L = sarcosinate anion; M = Co, Ni, Cu, Zn, Cd for L = N-phenylglycinate anion), which appear to be octahedral complexes. The metal is coordinated through a nitrogen atom, a carboxyl oxygen atom and water molecules or the carboxyl oxygen atoms of neighboring molecules. The latter type (B) consists of CoCl2 (HL)2·2H2O, ZnCl2 (HL)2 and CdCl2 (HL) (HL = sarcosine), in which the ligand has a zwitterion structure and has metal ions coordinated through only a carboxyl oxygen atom, but does not chelate through a nitrogen atom. In the cadmium (II) complex, a chloride ion seems to bridge to two cadmium (II) ions. In order to assign the observed frequencies of i.r. spectra in detail, normal coordinate analyses have been carried out for the complexes of the A type. The frequency separation of COO− antisymmetric and symmetric vibrations of A type complexes with sarcosine increases in the order: Co (II) < Ni (II) < Zn (II) < Cu (II). These separations of A type complexes with sarcosine and N-phenylglycine are larger than those of the corresponding complexes with glycine, alanine and other α-amino acids. The frequencies of metal-nitrogen and metal-oxygen stretching vibrations increase in the order: Co (II) < Zn (II) < Ni (II) < Cu (II) for sarcosine A type complexes.

Effect of bromomethane on the ignition in methane-oxygen-Argon mixtures behind reflected shock waves

Abstract The ignition delay times of methane-bromomethane-oxygen mixtures with argon were studied in the temperature range of 1400–2000K behind reflected shock waves. Ignition delay times, identified by the increase of pressure and OH emission, could be fit by the following expression: τ = 2.87 x 10 −11 exp (50,7OO/RT) X [ CH 4 l 0.33 [ O 2] −1.05 [ CH 3 Br ] 0.66 s The analytical investigation of the reaction mechanism gave calculated induction times in good agreement with experimental results. This system has 13 important reactions which control the induction time. Ignition was most sensitive to the following reactions: the decompositions of bromomethane and of formyl radical and the consumption of methyl radical.

Complexes of nickel(II), copper(II), zinc(II) and cadmium(II) with 4-hydroxy-L-proline

Complexes of four bivalent metals with 4-hydroxy-L-proline have been prepared and characterized by means of infrared absorption, powder diffuse reflection, electronic spectra, magnetic susceptibility, and thermal analysis. The complexes appear to be of three distinct types. The first type includes ML2·nH2O (M = Ni, Zn, Cu, L = 4-hydroxy-L-prolinato anion), and CuClL·H2O is a second type. In both the ligand chelates metal ions through the nitrogen atom of the pyrrolidine ring and the oxygen atom of the carboxylato group. CuL2 appears to adopt a cis geometry, and in the second type a chloride ion seems to bridge to two copper(II) ions. CdCl2HL is a third type, in which the cadmium ion is coordinated through the oxygen atom of the carboxylato group and chloride ions, but is not coordinated through the nitrogen atom.

Infrared absorption spectra and normal coordinate analysis of metal-dl-β-phenylalanine chelates

Abstract The infrared absorption spectra of dl -β-phenylalanine and its metal chelates have been investigated from 3700 to 270 cm−1. Detailed assignments of the observed absorption bands have been made based on a comparison of the spectra with the spectra of N-deuterated ligand and metal chelates, and with the spectra of some thoroughly studied, similar compounds. A normal coordinate analysis has been accomplished for the metal chelates as a 25-body problem utilizing a modified Urey-Bradley force field. The force constants obtained for metal-nitrogen bonds vary in the order Pt(II) > Cu(II) > Ni(II) = Co(II) = Zn(II). The nature of the carboxylate-metal bonding has been discussed, using the separation of the carboxylate antisymmetric and symmetric stretching vibrations as a basis for comparison. The separation increases in the order Ni(II) = Co(II)

The metal complexes of amino acids and their N-substituted derivatives—VI. The physical properties, i.r. spectra and normal coordinate analysis of bivalent metal complexes with dl-threonine

Abstract Complexes of five bivalent metals with dl -threonine have been prepared and characterized by means of i.r. absorption, powder diffuse reflection, and electronic spectra, X-ray diffraction and magnetic susceptibility. The complexes appear to be of three distinct types. The first type includes ML 2 · n H 2 O (M = Ni, Cu, Zn; L = dl -threoninato anion), in which the ligand chelates metal ions through the nitrogen atom and the oxygen atom of the carboxylato group. Three species of copper(II) complexes have been prepared. They seem to be two trans forms and one cis form. MnCl 2 (HL) 4 ·H 2 O is a second type in which the metal is coordinated through the oxygen atom of the carboxyl group and chloride ions, but is not coordinated through the nitrogen atom. 2CdCl 2 ·HL·HCl·2H 2 O is a third type, in which the metal is coordinated through only chloride ions. In order to assign the observed frequencies of i.r. absorption spectra in detail, a normal coordinate analysis has been accomplished for the complexes of the first type as a 33-body problem. Copper(II) and zinc(II) complexes with l -threonine have been prepared for comparison.

Infrared and Raman spectra and normal coordinate analysis of zirconium diphosphate

Abstract The i.r. and Raman spectra of zirconium diphosphate were investigated from 1300 to 200 cm −1 . A normal coordinate analysis was performed assuming that the diphosphate ion had D 3 d symmetry, and an approximate description of the vibrational modes was assigned to the observed frequencies. The agreement between the observed and calculated frequencies is satisfactory; this indicated that the diphosphate ion in zirconium diphosphate had D 3 d symmetry to good approximation.