G. Ponticelli

ESR studies on some five coordinate copper (II) complexes in solutions

ESR and optical absorption studies have been made on four 5‐coordinate copper complexes, namely, Cu (trien) Br2, Cu (trien) (ClO4)2, [Cu (trien) NCS]Bφ4, and Cu (Me6trien) Br2 (where trien and Me6trien stand for triethylylenetetramine and N,N,N′N″,N‴,N‴‐hexamethlytrien, respectively) in solutions to study metal ligand bond nature and different contributions to line widths. The 4s character in the ground state is estimated and is found to influence spin‐Hamiltonian constants, bond parameters, and hyperfine linewidth. The hyperfine linewidth at room temperature is explained using the theory of Wilson and Kivelson.

3,5-diphenylisoxazole as ligand. Complexes of cobalt(II), nickel(II) and copper(II)

Abstract Some complexes of cobalt(II), nickel(II) and copper(II) chloride, bromide, iodide, thiocyanate and perchlorate with 3,5-diphenylisoxazole (3,5-diPhisox) have been prepared and characterized. On the basis of vibrational and electronic spectroscopy, magnetism and conductivity measurements, the structures of these complexes were identified. The ligand behaves both as monodentate N-bonded, and as a bridging N- and O-bonded ligand. All the compounds here reported have an octahedral stereochemistry with the exception of [Co(3,5-diPhisox)2X2] (X = Cl, Br, I, NCS), which are tetrahedral, while the complex [Cu(3,5-diPhisox)4] (ClO4)4·4H4O is square planar.

Electron spin resonance studies on Cu(N-Ethyl imidazole)4(ClO4)2 and Cu(N-Propyl imidazole)4(ClO4)2

Abstract Electron spin resonance (ESR) studies have been made on the undiluted Cu(N-ethyl imidazole) 4 (ClO 4 ) 2 and Cu(N-propyl imidazole) 4 (ClO 4 ) 2 complexes in their polycrystalline forms at 295 and 77 K. The spectra are characterized by the resolution of cupric ion hyperfine splittings which is not usual. The g - and A -values are typical of square planar symmetry with monodentate ligands. Surprisingly the nitrogen hyperfine splitting could not be resolved either at 295 or at 77 K. The widths of various components in the spectra showed little variation from room temperature to the temperature of liquid nitrogen leading to the conclusion that the contribution to linewidth from spin-lattice relaxation is negligible and a sufficient amount of spin-spin interaction is still present to smear the nitrogen hyperfine splittings. These couid, however, be resolved by effecting a dilution of the copper complexes with 5 per cent of zinc perchlorate. The MO coefficients have been evaluated using ESR and optical absorption data.

Electron spin resonance and electronic spectral investigation on square planar copper(II) complexes ofN-ethyl- andN-propylimidazole

SummaryElectron spin resonance studies have been carried out onN-ethylimidazole andN-propylimidazole 4 : 1 complexes of CuX2 salts (X = ClO4−, NO3−, , Br− or Cl−) in their polycrystalline and undiluted form at 295 K and 77 K. Cupric ion hyperfine structural resolution is observed for all the complexes at 295 K and the spectra are characteristic of a CuN4 chromophore with axial symmetry. In complexes involving ClO , Br− and Cl− the anions are nonbonding, whereas those with the NO3− anion are weakly bonding. The electronic and e.s.r. spectral data have been correlated. The resolution of Cu2+ ion hyperfine structure in these complexes is attributed to a decrease in the dipolar interaction and has been observed for the first time since the first resolution reported in 1954 for CuN4 coordination with square planar symmetry for α,β,ν,σ-tetraphenylporphyrincopper (CuTPP).

Mixed ligand complexes of 3,3′-diaminodipropylamine and ethylenediamine or 1,3-diaminopropane with copper(II)

Abstract Preparations of new mixed ligand complexes of 3,3′-diaminodipropylamine (dpt) and ethylenediamine (en) or 1,3-diaminopropane (tn) with copper(II) of the type [Cu(dpt)(L)]X2, (where L is en, tn; X is Cl−1, Br−, I−, ClO4−) are described and their infrared, electronic spectra and magnetic susceptibilities are reported. The metal seems to be five-coordinate with a pyramidal square configuration.

Palladium(II) and platinum(II),(IV) complexes of 2-aminopyrimidine derivatives

Palladium(II) and Platinum(II),(IV) complexes with 2-aminopyrimidine derivatives (L1)–(L3), prepared by reacting the corresponding metal halide with the ligand in the required stoichiometric ratio, were characterised by chemical analyses and physical measurements. The structures have been assigned on the basis of i.r. spectroscopy, electronic reflectance spectra and molar conductivities.

Complexes of copper(II), nickel(II) and cobalt(II) with 2-fluoro,5-nitroaniline and 4-fluoro,2-nitroaniline

Abstract Preparation of new complexes of 2 - fluoro,5 - nitroaniline (2-F,5-NA) and 4 - fluoro,2 - nitroaniline (4-F,2-NA) of the type ML n X 2 · m H 2 O (where M = Cu(II), Ni(II), Co(II); L = 2-F,5-NA; 4-F,2-NA; n = 2,4,6; X = Cl − , Br − , SCN − , ClO 4 − ; m = 0–2) are described and their i.r., electronic spectra, and magnetic moments are reported. The ligands act always as monodentate O-bonded. The compounds are generally high spin, non electrolytes, and present square planar, tetrahedral and hexacoordinate structures.

Cobalt(II) and copper(II) complexes of 3-amino-5-methylisoxazole

SummaryCobalt(II) and copper(II) halide, nitrate, thiocyanate and perchlorate complexes of 3-amino-5-methylisoxazole (3-AMI) have been prepared and characterized by means of magnetic, spectroscopic and molar conductivity measurements. In Cu(3-AMI)2X2 compounds (X = Cl, Br, N02) the 3-AMI ligand is bridging and bidentate [N (ring), O(bonded)]. In the other derivatives it is monodentate [N(ring) bonded]. All cobalt(II) complexes have an octahedral stereochemistry, if the Co(3-AMI)2X2 derivatives (X = Cl, Br), which are tetrahedral, are excluded. Copper(II) complexes have generally a distorted square pyramidal stereochemistry in the solid state and in solution.

Square-planar copper(II) complexes with a novel tetradentate amido-carboxylate ligand. Crystal structure of [Co(H2O)6][Cu(mda)] · 2H2O

A novel O—N—N—O-type tetradentate ligand H4mda (H4mda = malamido-N,N′-diacetic acid) and the corresponding square-planar copper(II) complexes have been prepared and characterized. The mda4− ligand coordinates to the copper(II) ion via two pairs of deprotonated ligating atoms (two carboxylate oxygens and two deprotonated amide nitrogens) with in-plane square chelation. A four-coordinate, square-planar geometry has been established crystallographically for the [Co(H2O)6][Cu(mda)] · 2H2O complex. Structural data correlating the square-planar geometry of the [Cu(mda)]2− unit are discussed in relation to information obtained for similar complexes. The i.r., electronic, absorption and reflectance spectra of the complexes are analysed in comparison with related complexes of known geometries.

The favored uns-cis geometry in octahedral nickel(II) complexes containing linear tetradentate edda-type ligands forming six-membered rings. Crystal structure of uns-cis-[Ni(1,3-pdda)(H2O)2]

Two paramagnetic octahedral nickel(II) complexes containing the tetradentate 1,3-propanediamine-N,N′-diacetate (1,3-pdda) or ethylenediamine-N,N′-propionate (eddp) anions and water in the remaining two coordination positions were prepared and characterized. In both cases, only one (uns-cis) of the three geometrical isomers, was found to dominate. The 1,3-pdda and eddp ligands prefer the uns_cis configuration, indicating that six-membered chelate rings have a profound effect on the distribution of geometrical isomers. The infrared and electronic absorption spectra of these complexes are discussed in comparison with those of an edda-Ni(II) complex (eedda=ethylenediamine-N,N′-diacetate ion) of known s-cis configuration. The electronic absorption spectra have been treated in terms of Oh symmetry but the splitting of the 3T2g(Oh) bands of the complexes indicates that the tetragonal field is enhanced. The splitting patterns are assigned with the D4h model: 3B1g→3B2gand 3B1g→3Eg. The magnetic measurements are also reported for the complexes studied. The uns-cis-[Ni(1,3-pdda)(H2O)2] complex crystallizes in the space group P212121 of the orthorhombic crystal system with a=15.982(4), b=8.502(2), c=8.032(2) (A) and Z=4. The six-membered diamine ring assumes the stable ‘chair’ conformation. The five-membered glycinate rings show a relatively small puckering resembling an ‘envelope’ conformation.