Krzysztof Kurzak

UV–Vis–NIR spectroscopy and colour of bis(N-phenylsalicylaldiminato)cobalt(II) in a variety of solvents

Abstract Cobalt(II) complex with Schiff base obtained by condensation aniline with salicylaldehyde cobalt(II) complex, was studied in variety of solvents. The product i.e. salicylidene-anilinecobalt(II) ([Co(salan)2]) complex is a red crystalline compound easily soluble in common solvents like chloroform (CHCl3), benzene (Bz), toluene (MBz), dioxane (DX), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and acetonitrile (ACN) that is a necessary condition to observe solvatochromism. It has been characterised by elemental analyses, molar conductivities, ultraviolet (UV) and visible (Vis) spectroscopy. The molar conductivities indicate their non-electrolytic properties in all the solvents. Electronic spectra have been used to postulate the tetrahedral geometry for the species in solutions and to determine the coordination properties of ligators and their bonding abilities (ligand-field parameters), as well as their solvatochromism. The results obtained show fine colour changes. For discrimination of colour changes we applied CIE and CIELAB colour spaces.

Potentiometric and spectroscopic studies of the copper(II) complexes with some aminodiphosphonic acids in aqueous solution

The stoichiometries and stability constants of the copper(II) complexes with seven aminodiphosphonates [R–N(CH2PO3H2)2, L] containing iminomethylenephosphonate moieties have been determined pH-metrically at 25°C and at an ionic strength of 0.20 mol dm−3 (KCl). The results suggest for L=1–6 only equimolar species: [Cu(H2L), [Cu(HL), [CuL] and two hydroxo [CuH−1L] and [CuH−2L], in the pH range of 2–11.5, the only difference is the presence of an additional [Cu(H3L)] species (∼15%) at low pH for N-3-picolyliminodi(methylenephosphonic) acid. For L=7 the model contains protonated and non-protonated 1:2 species. From the comparative analysis of the stability and the spectroscopic (UV–VIS and EPR) data it has been established that the ligands in [CuHL] and [CuL] are tridentate; the formation of two five-membered chelate rings leads to very stable complexes. The LMCT bands from O− (PO32−) and Nimino to Cu2 are at 225–231 and 302–277 nm.

Potentiometric and spectroscopic studies of the cobalt(II), nickel(II) and manganese(II) complexes with some aminodiphosphonic acids in aqueous solution

Abstract The stoichiometries and stability constants of the manganese(II), cobalt(II) and nickel(II) complexes with seven aminodiphosphonates [RN(CH 2 PO 3 H 2 ) 2 , L] containing iminomethylenephosphonate moieties have been determined pH-metrically at 25°C and at an ionic strength of 0.20 mol dm −3 (KCl). The results suggest for L= 1 – 6 only equimolar species: [M(H 2 L)], [M(HL)] − , [ML] 2− and hydroxo [MH −1 L] 3− , in the pH range of 3–11.5, the only difference is the presence of an additional [M(H 3 L)] + species at low pH for N -3-picolyliminodi(methylenephosphonic) acid. For L= 7 the models contain protonated and non-protonated 1:2 species. From the comparative analysis of the stability and the spectroscopic (UV–VIS) data it has been established that the ligands coordinate to the metal ions only by the phosphonate group(s) in a monodentate or bidentate manner. The LMCT bands from O − (PO 3 2− ) to Ni 2+ are at 222–211 nm.

Spectrochemical properties of cobalt(II) complex with bidentate Schiff base in various solvents

As a continuation of our previous studies on copper(II) complexes with a bidentate Schiff base derived from 5-bromosalicylaldehyde and α-aminopyridine, we have investigated the electronic spectra of the cobalt(II) complex with this ligand. The complex is a red crystalline compound soluble in common solvents, such as chloroform, dioxane, dimethyl formamide, dimethyl sulfoxide, and methanol. The time-elapsed spectral measurements of the complex and ligand, as well as conductivities of the complex in chloroform and dioxane solutions, are presented and discussed. Molar conductivities indicate that the complex exists as a nonelectrolyte in nonpolar solvents and as a 1:1 or 1:2 electrolyte in polar solvents. The ligand-field parameters (CFM/AOM) for the complex in chloroform solution are estimated and discussed.

Reactions of commercial ruthenium chlorides with O-donor ligands. Reactions with water: u.v.-vis. investigation of soluble products; analysis, thermogravimetry and an i.r. study of precipitated solids

SummaryThe u.v.-vis. absorption spectra of the products of reaction of commercial ruthenium chlorides with water have been measured. Deconvolution analysis revealed that hexaaquo-, pentaaquohydroxy- and pentaaquo-chlororuthenium(III) ions are formed, in addition to four unknown compounds.Analysis of the concentration data suggests the formation of soluble oligomers of the primary products over several hours following dissolution. Storage of the solution for ca. 170 h furnishes insoluble materials, characterized by analysis, thermogravimetry and i.r. The bulk of these solids can be described as [Ru2n + 2O3n + 3] ·mH2O or [Ru2n + 2O(3n + 3) - a(OH)2a·mH2O. We suggest the existence of ruthenium hydrides in these precipitated solids.

Spectrochemical properties of noncubic transition metal complexes in solutions—IV. Energy levels of tetragonal distorted chromium(III) complexes in aqueous solutions

Abstract A general method for the analysis of the d-d transition energies observed in the ligand field spectra of chromium(III) complexes with D 4 h or C 4υ symmetry is described and used to derive the crystal field and angular overlap parameters for the complexes of known stereochemistry. Examples are also presented. The spectrum of the diamminetetrakis(isothiocyanato)chromate(III) ammonium in aqueous solution is reported. The spectra of the miscellaneous systems have been studied theoretically using a crystal field model and an angular overlap model.

The spectrochemical properties of non-cubic transition metal complexes in solutions. II, Mixed tetragonal distorted nickel(II) pyridine complexes in methanol

The electronic spectra of tetragonal nickel(II) complexestrans-[Ni(Py)4L2], (Py=pyridine and L=NCS, Cl, Br, or I) have been measured in a 10% pyridine solution in chloroform at room temperature. The experimental curves were resolved by Gaussian analysis. The various ligand field parameters are discussed in terms of their chemical utility and their relation to ligand-field strengths. The ligand field parameters were examined by the dumped nonlinear least-squares algorithm (Gauss-Newton method) and Powell solution-seeking (nongradient) algorithm. The standard deviations of the parameters have been obtained from the former. Finally, it was found that the structure of the complexes in chloroform solution are much the same as in the solid state.

Spectrochemical properties of noncubic transition metal complexes in solution. Part III. Mixed tetragonal distorted nickel(II) pyridine complexes in dimethyl sulphoxide

SummaryThe electronic absorption spectra of the tetragonal Ni(py)4X2 complexes (py=pyridine and X=NCS−, Cl−, Br− or I−) in dimethyl sulphoxide (DMSO) solution have been measured at room temperature. The experimental curves were resolved by Gaussian analysis. The crystal field (CFM) and angular overlap (AOM) parameters were calculated by the Davidon-Fletcher-Powell method (gradient estimation). The assumed structures in solution are, for the iodide complex, [Ni(py)4(DMSO)2]I2 and for the others [Ni(py)4(DMSO)X]X (X=Cl−, Br−) and [Ni(py)4X2] (X=NCS−). A comparison of the spectra, ligand field parameters and stereochemistries in various solutions was made.

The spectrochemical properties of noncubic transition metal complexes in solutions. Part I. Mixed tetragonal distorted nickel(II) pyridine complexes in chloroform

SummaryThe electronic spectra of tetragonal nickel(II) complexestrans-[Ni(Py)4L2], (Py=pyridine and L=NCS, Cl, Br, or I) have been measured in a 10% pyridine solution in chloroform at room temperature. The experimental curves were resolved by Gaussian analysis. The various ligand field parameters are discussed in terms of their chemical utility and their relation to ligand-field strengths. The ligand field parameters were examined by the dumped nonlinear least-squares algorithm (Gauss-Newton method) and Powell solution-seeking (nongradient) algorithm. The standard deviations of the parameters have been obtained from the former. Finally, it was found that the structure of the complexes in chloroform solution are much the same as in the solid state.

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. XV. Solution Properties of bis(Salicylideneaniline)Copper(II)

The complex obtained by condensation of salicylideneaniline with copper(II) acetate was studied in a variety of solvents. This deep-brown crystalline compound is soluble in common solvents, such as, chloroform, toluene, dioxane, methanol, ethanol, dimethyl formamide, dimethyl sulfoxide, and acetonitrile—a necessary condition for observing solvatochromism. The complex has been characterized by elemental analysis, molar conductivity, EPR, and ultraviolet (UV) and visible (VIS) spectroscopy. The available X-ray data shows planar coordination geometry for the copper center. Combined multi-technique experiments have been applied to confirm the structure of the complex in solution. The molar conductivities indicate nonelectrolytic properties. EPR measurements preclude the possibility of solvent coordination at the axial positions of the complex. Spectroscopic measurements were used to study the coordination properties of donor atoms and their bonding ability, as well as trichromaticity coordinate calculations. The results obtained show that the interactions of metal with donors depend on donor strength and polarity of solvent.