Ján Gažo

Cyanato-copper(II) complexes with organic ligands—XIII[1]: Isomerism with dicyanato-bis(2,4-lutidine)-copper(II)

Abstract Two new isomeric forms of Cu(NCO)2(2,4-lutidine)2, a violet β and a blue γ, were prepared and examined by several physical methods. According to X-ray diffraction patterns the crystal structure of the β-isomer is very close to that of the known α-isomer, whereas the γ-isomer has a considerably different crystal structure. The electronic spectra indicate a tetragonal structure for the β-isomer, this being slightly more distorted than the α-form, and a pseudooctahedral structure for the γ-isomer. The IR spectra give evidence for N-bridging by the NCO groups in the γ-isomer which is ferromagnetic, and the temperature dependence of its susceptibility conforms with an anisotropic Ising model for g = 2·19 and 2J = +9·0 cm−1. In this isomer axial ligation of Cu(NCO)2(2,4-lutidine)2 entities takes place by nitrogen atoms from the NCO groups. These results show that α- and β-Cu(NCO)2(2,4-lutidine)2 represent pure distortion isomers, and that the reduced distortion of γ-Cu(NCO)2(2,4-lutidine)2, by comparison with the α- and β-form, is related to the linkage isomerism.

Ligand and distortion isomers isolated from the Cu(II)NCO−-pyrazole system

Abstract From the Cu(II)NCO−-pyrazole (pz) system two pairs of isomeric compounds were isolated. The IR spectra show that the first pair represents the cyanato complexes Cu(NCO)2(pz)2, while the second includes the compounds Cu(pz.NCO)2, containing 1-carbamoylpyrazolate anions as chelating ligands. According to the ligand field spectra the compounds of each pair differ in the distortion of the pseudooctahedral Cu(II) atom environment. The ESR spectra and the temperature dependent magnetic data reveal a considerable exchange interaction.

Formation of a new ligand by addition of 3,5-dimethylpyrazole to the cyanate group in a copper(II) complex: crystal and molecular structure of α-bis(1-carbamoyl-3,5-dimethylpyrazolato)copper(II) and the physical properties of two isomeric forms

Two forms (α and β) of the compound [Cu(dmpz.NCO)2](dmpz = 3,5-dimethylpyrazole) have been prepared and the structure of the α form established by single-crystal X-ray analysis. The crystals are monoclinic, space group P21/c, with a= 13.697(7), b= 14.759(7), c= 7.463(7)A, β= 114.01(3)°, and Z= 8. The structure has been solved by the heavy-atom method and refined by full-matrix least squares to R= 0.052 for 1 760 independent reflections. The compound consists of nearly planar molecules, in which two 1-carbamoyl-3,5-dimethylpyrazolate anions are co-ordinated to the CuII atom, the Cu–N distances being 1.926(8), 1.908(1), 1.985(8), and 1.990(8)A. This new ligand originates from a nucleophilic addition of the dmpz molecule to the NCO group in the CuII coordination sphere. Both forms have been studied by i.r., solid-state electronic and e.s.r. spectroscopy, and by variable-temperature magnetic susceptibility measurements. The results obtained show that substantially the same molecules are present in the β as in the α form, but an appreciable out-of-plane interaction of the CuII atoms with potential donor atoms of other molecules takes place.

Der Einfluß von methyl- und dimethylsubstituierten Pyridinen als Liganden auf die Struktur und den Elektronentransfer bei Thiocyanat-Kupfer(II)-Komplexen

Complexes of the type Cu(NCS)2L2 whereL are all isomeric picolines and lutidines, as well as those of the type Cu(NCS)2L3 forL=β-, γ-picoline, 3,4-, and 3,5-lutidine were prepared. The complexes were studied by means of thermal decomposition, and by electronic andESR spectroscopy. The results obtained have been brought into correlation with the effect of the ligandsL being caused by the methyl groups on the pyridine ring. It has been found that the differences in the properties studied which appear between Cu(NCS)2L2 and Cu(NCS)2(pyridine)2 are conditioned especially by the steric effect of the ligandsL with the methyl group in α-position. The other ligandsL, however, show also an influence on some properties of the respective complexes.

Darstellung und Eigenschaften zweier isomerer Formen des Dichloro-bis[triphenylphosphinoxid—Kupfer(II)]-Komplexes

Cu(OPph3)2Cl2 exists in yellow α- and orange β-isomeric forms. β-Cu(OPph3)2Cl2 was prepared by thermal decomposition of Cu(OPph3)4Cl2·2 H2O and by reaction of CuCl2 with OPph3 in acetone—ethanol mixture at higher temperature. The results of magnetic measurements, electronic andESR spectra show that the structure of β-isomer differs from the known structure of the α-isomer by a different degree of distortion of the coordination tetrahedron. α-Cu(OPph3)2Cl2 is thermodynamically more stable then β-Cu(OPph3)2Cl2.

Einfluß der Alkylgruppen auf die Struktureigenschaften der Cyanato-Kupfer(II)-Komplexe mit Alkylpyridinen

New cyanato-copper(II) complexes of the type Cu(NCO)2L2 (L=2,3-, 2,5-, 3,4- or 3,5-lutidine, 3- or 4-ethylpyridine) and Cu(NCO)2L (L=2,3- or 2,5-lutidine, 2-ethylpyridine) were prepared. Solid state electronic, ESR and IR spectral results show, that Cu(NCO)2L2 complexes have tetragonal structures varying from pseudooctahedral to practically planar forms, also involving a square-pyramidal arrangement. The β-form of Cu(NCO)2(2-picoline)2 was isolated and found to be a distortion isomer of the known α-form. According to physical results, Cu(NCO)2L complexes exhibit highly distorted five-coordinate structures. Further knowledge about the influence of type, number and position ofL ligand alkyl groups on the structure-bonding properties of cyanato-copper(II) complexes was obtained.

Studium des gegenseitigen Einflusses der Bindungen in Thiocyanat-Kupfer(II)-Komplexen mit Methyl- und Dimethylpyridinen mittels Infrarotspektroskopie

The infrared spectra of thiocyanato-copper(II) complexes of the type Cu(NCS)2L2 with all isomeric picolines and lutidines (L) as well as those of the type Cu(NCS)2L3 withL=3- and 4-picoline, 3,4- and 3,5-lutidine were measured. The behaviour of the ν (CN) stretching vibrations of the Cu(NCS)2L2 complexes led to conclusions on the different kind of coordination of the NCS groups in dependence on the ligandL. The mutually conditioned strength of the Cu−NCS and Cu−N(L) bonds in the equatorial plane, especially in the presence of ligandsL with the steric effect, was determined from the frequency shift of the Cu−NCS and Cu−N(L) stretching vibrations with regard to the vibrations for Cu(NCS)2(pyridine)2.

X-Ray and infrared evidence of new ligand formation by addition of 3,5-dimethylpyrazole of the cynate group in a copper(II) complex

Two forms of the compound [Cu(NCO)2(dmpz)2] have been prepared (dmpz = 3,5-dimethylpyrazole); in the nearly planar molecules of the α-form the uncoordinated dmpz nitrogen atom is linked t o the carbon atom of the NCO group, thus forming a new chelating ligand with a bent NCO skeleton.

Die Herstellung und einige physikalisch-chemische Eigenschaften von Modifikationen des Dipyridin-Dirhodankupfer(II)-Komplexes

The paper deals with the preparation of modifications of Cu(Py)2(CNS)2 from aqueous media. The α-from was obtained by precipitation of pyridine containing solutions of CuSO4 with NH4CNS, while for the β-modification crystallisation from solutions was applied that in addition to the above components contained also ammonia. The differences betwwen the modifications are discussed on the basis of their infra-red spectra, their thermograms and their powder-diffractograms. The structural differences are localized in the inner coordination sphere of the central atom. Besides, also the properties of some products of the thermal decomposition of these modifications are reported.

Crystal and molecular structure of the adduct between dichlorodiaqua-copper(II) and triphenylphosphine oxide

The X-ray crystal structure of Cu(OPPh3)4(H2O)2Cl2 shows that the compound is an adduct of dichlorodiaquacopper(II) and triphenylphosphine oxide; the adduct unit is formed by one CuCl2(H2O)2 square-planar complex unit and four molecules of triphenylphosphine oxide which are bonded to the comlplex unit by hydrogen bonds.