EXAFS zinc complexes

Parkhurst DA, Brown GE Jr, Parks GA, Waychunas GA (1984) Structural study of zinc complexes in aqueous chloride solutions by fluorescence EXAFS spectroscopy. Abstracts with Program Geol Soc Am AnnMtg 16 618... 

Entering group effect platinum complexes substitution reactions, 494 EXAFS spectroscopy cadmium complexes, 929 copper(II) complexes, 720 zinc complexes, 929... 

X-ray diffraction studies on alkoxy-dithio-benzoato zinc complexes [Zn(n-odtb)2] showed that in the solid state the material is a dimer containing an eight-membered Zn-S-C-S-Zn-S-C-S ring the dimer held together in the nematic phase and disappeared in solution where is found a monomeric structure [85]. This work is confirmed by EXAFS studies [90]. 

Reduction by zinc amalgam of a dry and oxygen-free THF solution containing [VC12(TPTP)] (TPTP = raeso-tetra-p-tolylporphyrinato) and addition of elemental sulfur yields [VS(TPTP)].659 Similar thiovanadyl complexes were prepared with OEP, TPP and TMTP (TMTP = meso-tetra-ra-tolylporphyrinato). Analytical results and mass spectra agree with the formulation [VS(por)], and v(V=S) was at 550-565 cm-1 (see Section 33.5.6.1). FT-EXAFS of [VO(OEP)] and [VS(OEP)] were recorded and the difference FT spectrum yielded... 

The formation of axially substituted complexes MLL (M = Zn or Cd H2L = porphyrin L = another ligand) has been investigated by a number of groups.1155-1158 An EXAFS study has shown that there is no short axial Zn—S interaction in peptide-substituted zinc porphyrins, in which the side chain bears a cysteine residue.1159 ... 

Local description of the arrangement around cations concludes unambiguously for [Cu-Cr-Cl] in a cationic ordering. The evidence of similar ordering for [Zn-Cr-Cl] was only obtained by a combined EXAFS and UV-Vis study of the formation of this LDH in solution [18], The structural pathway so-reported involves the heterocondensation between hexa-aquo zinc(II) complexes and deprotonated chromium monomers. 

In addition to lead, the form of zinc in the Fe plaque of Phalaris arundinacea was also examined by fluorescence microtomography and EXAFS spectroscopy (Fig. 27, Hansel et al. 2001). Unlike lead, which was clearly associated with Fe (oxyhydr)oxides and inferred to be complexed to organic molecules, zinc was clearly correlated to manganese. On the basis of Mn-0 (2.20 A) and Zn-0 (1.96 A, 2.06 A, 2.08 A, 2.15 A) EXAFS distances, Mn was assumed to be speciated as rhodochrosite (MnC03) and Zn as hydrozincite (Zn5(0H)6(C03)2). While this study documented for the first time the combined use of fluorescence microtomography and EXAFS spectroscopy, and... 

The zinc(II) complex 59 was obtained by the reaction of Zn(MeCN)4(BF4)2 with the corresponding sodium salt of dithiocarboxylic acid and subsequent recrystallization from pyridine (Fig. 15) [114]. The crystal structure was shown to be a distorted trigonal bipyramidal geometry with one sulfur atom from each of the dithiocarboxylato ligands occupying the axial sites. In the absence of donor molecules such as pyridine, one sulfur atom from the dithiocarboxylato ligand coordinates to another zinc center to form a dimer-like Zn(II) complex 60 in the crystalline state [115]. EXAFS study indicates that 60 retains the dimeric nature in the mesophase. 

The application of X-ray absorption spectroscopy (XAS), X-ray absorption nearedge structure (XANES), and EXAFS to tetrapyrroles that are not iron porphyrins is as yet relatively limited. Studies include EXAFS of 3-propenamide-zinc(II)-mcso-tetraphenylporphyrin complexes [201], XANES of vanadyl-phthalocyanine and vanadyl-meso-tetraphenylporphyrin [202], and XANES of iron(III)-phthalocyanine and its CO adduct [203]. 

Stromberg D, Sandstrom M, Wahlgren U (1990) Theoretical calculations on the stracture of the hexahydrated divalent zinc, cadmium and mercury ions. Chem Phys Lett 172 49-54 Svegensky DA, Shock EL, Helgeson HC (1997) Prediction of thermodynamic properties of aqueorrs metal complexes to 1000°C and 5 kb. Geochim Cosmochim Acta 61 1359-1412 Tabata M, Ozutsumi K (1992) Eqirilibrium and EXAFS studies of mercury(II) porphyrin in aqueous solution. Brrll Chem Soc Jap 65 1438-1444... 

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