Zbigniew Staszak

Synthesis, spectroscopic and magnetic studies of chromium(II) complexes isolated from in vitro reduction of the chromium(VI) ion with the main cellular reductants ascorbic acid, cysteine and glutathione*

Abstract The redox chemistry of chromium(VI) is presented with respect to the final products of the interaction of K2CrO4 with main cellular reductants. The isolation of a family of chromium(III) complexes obtained from the reduction of the chromate ion with ascorbic acid, crysteine and glutathione is described. The compounds have been characterized by elemental, IR and electronic spectroscopy and magnetic measurements. All complexes exhibit a tetragonal deformation around chromium(III) with the MO4XX′ chromophore (X,X′—O′,S,N).

Systematic investigation of the [Ni2+–phen–CrO42−] system; dichromate species isolated from alkaline solutions

Abstract Nickel(II) dichromate and chromate complexes with 1,10-phenanthroline were isolated from basic (pH 8–9) solutions. [Ni(phen)3]Cr2O7·8H2O (1), NiCrO4 (2), [Ni(phen)3]Cr2O7·3H2O (3) and [Ni(phen)(OCrO3)(H2O)3]·H2O (4) were characterized with spectroscopic (UV–Vis, IR, FIR) methods and one (4), additionally, with X-ray data. In the complex (4) the chromate ion is monodentately coordinated to nickel ion. This complex crystallizes in the triclinic crystal system (space group P 1 ). The single crystal electronic spectrum of complex (4) at 4 K reveals a rare feature when the structured second d–d band (Oh symmetry) is unsplit in spite of lowering symmetry. The filtration process has revealed that this band is vibronically structured in the νs NiOCr quantum. A new broad low intensity band at approximately 14 000 cm−1 was assigned to the forbidden transition in the bridge. An attempt to explain precipitation of dichromates from alkaline solutions has been given.

Synthesis, crystal structure and spectroscopic characterisation of double salt [Zn(bpy)3](CrO4)0.5NO36.5H2O

Abstract A new Zn(II) complex with 2,2′bipyridine (bpy), chromate and nitrate groups, [Zn(bpy)3](CrO4)0.5NO36.5H2O has been prepared and characterised with crystallographic and spectroscopic methods. The orthorhombic complex crystallises in the space group Ccc2 with the lattice constants a=13.992(3) A , b=24.483(5) A , c=21.556(4) A and Z=8. The coordination environment about Zn(II) ion is nearly octahedral. The CrO42− and NO3− entities exhibit anionic position in the crystal. The electronic spectra enhanced with mathematical methods (filtration and deconvolution) exhibit the presence of vibrational fine structure in the CrO42− entity on the spin-forbidden 3T1 transition.

Influence of the Bulk and Donor-Acceptor Properties of Solvent on Ligand Field Spectra

Abstract The influence of solvents on the electronic absorption spectra of chromium (III) complexes was investigated. The dependence of the crystal field parameter Dq on dielectric constant as well as Gutmann donor number DN of solvent was found and described. By using the proposed model, unknown in the literature donor numbers for a few alcohols were estimated.

Application of the Digital Filter Method to Analysis of the d—d Absorption Bands in the Spectra of Cr(III) Complexes

Abstract A variable digital filter method was used to obtained well resolved solid state electronic spectra of Cr(III) complexes with ascorbic acid, cysteine and glutathione. Details of the filtered spectra such as symmetry lowering of the systems and fine structure were analyzed in terms of tetragonal distortions in the coordination sphere of the Cr(III) ion. Crystal field: Dq, Ds, Dt as well as Racah parameters B have been calculated.

Homo- and hetero-nuclear chromium(III) complexes with natural ligands. Part 1. Spectroscopic and mass spectra studies on ternary [M–L1–L2] systems

Seven new ternary mono- and poly-nuclear CrIII complexes with natural ligands: glycine, glutaminic, nicotinic and asparginic acids, cysteine and glutathione, have been isolated and physicochemically characterized. Four of them have been tested and appear to be non-toxic. The complexes have been analysed using spectroscopic (diffuse reflectance U.v–vis., i.r., f.i.r.), magnetic methods, and (some) by FAB mass spectra. Spectral analyses with the digital filter and band deconvolution methods have been also presented.

The reactivity of cis-platin. Spectroscopic properties of products isolated from the [cis-Pt(NH3)2Cl2–quercetin] and [cis-Pt(NH3)2Cl2–CrVI–quercetin] systems

New coordination compounds: [PtIIQ] and [PtIV–CrIIIQ2], where Q = quercetin, were isolated from the [Pt(NH3)2Cl2–quercetin] and [Pt(NH3)2Cl2–CrVI–quercetin] systems, respectively. Structures are proposed on the basis of i.r., n.m.r. and deconvoluted electronic spectra.

Structural, spectroscopic, magnetic behavior and DFT investigations of L-tyrosinato nickel(II) coordination polymer

New 1D-coordination polymer {[Ni(L-Tyr)2(μ-4,4′-bpy)]·4H2O}n (1) (L-Tyr = L-tyrosine, 4,4′-bpy = 4,4′-bipyridine) is composed of L-tyrosinate anions chelated nickel(II) centres via N amino and O carboxylate atoms, whereas the apices of the elongated octahedral coordination sphere are occupied by the N atoms of 4,4′-bipyridine. Its molecular structure was determined by single-crystal X-ray diffraction and characterized using vibrational (FT-IR), Raman spectroscopy (FT-Raman), electronic (NIR-Vis-UV) and high field electron paramagnetic resonance (HF-EPR) spectroscopy and thermal (TG-DTA, DSC) and magnetic methods. The tetragonality distortion parameter (T) equals 0.945. The gx, gy and gz parameters (HF-EPR spectra) are slightly temperature dependent and the set gx = 2.178(5), gy = 2.156(4), gz = 2.19(1), D = −5.76(2) cm−1, E = −0.41(1) cm−1 was found at 5 K. The analysis of the temperature and field dependent magnetization shows the weakness of magnetic interactions in 1.

Homo- and hetero-nuclear chromium(III) complexes with natural ligands. Part 3. Chromium(III)/vanadium(IV) species isolated from the redox systems

Four new heteronuclear CrIII/VIV complexes have been isolated from the redox [CrIII–Vv–L1–L2] systems (L1 = glycine, glutaminic and nicotinic acids, L2 = cysteine and glutathione). The complexes have been analysed by spectroscopic methods (diffuse reflectance u.v./vis., i.r.) and by FAB mass spectra. A significant bathochromic shift of the d–d CrIII and VIV transitions in heteronuclear complexes (d1–d3) in comparison to the CrIII homonuclear species (d3/d3) has been related to the interaction of two metal centres. Spectral analyses by the digital filter and band deconvolution methods are presented.

Solvent Effects on the Electronic Absorption Spectra of Cr(III) Complexes

Abstract An influence of the protic solvents on the electronic absorption spectra of chromium (III) complexes was investigated. The high correlation between dielectric constant of solvents and the crystal field parameter Dq as well as between refractive index and oscillator strength of d-d bands were observed. The significance of the ligand - second sphere interactions for studying of solvent effect on complex spectra was stated.