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Complexes of general formula MLmCl2 · nH2O, where M=cobalt(II) or nickel(II); L=2-(4′-methyl, 2′-pyridyl)-benzimidazole (mpbi), 2-(4′-methyl, 2′-pyridyl)benzothiazole (mpbt), 2-(4′-methyl, 2′-pyridyl)benzoxazole (mpbo), 2-(4′-methyl, 2′-quinolyl)benzoxazole (mqbo), or 2-(4′-methyl, 8′-quinolyl)benzoxazole (mq′bo); m=1,2; n=0–3, were prepared and characterized by t.g.a., conductance and magnetic measurements, i.r. and diffuse-reflectance electronic spectra.

Copper(II) complexes CuLCl2, where L=2-(4′-methyl-2′-pyridyl)benzimidazole(mpbi); 2-(4′-methyl-2′-pyridyl)benzothiazole(mpbt); 2-(4′-methyl-2′-pyridyl)benzoxazole (mpbo); 2-(4′-methyl-2′-quinolyl)benzoxazole (mqbo); 2-(4′-methyl8′-quinolyl)benzoxazole (mq′bo), and Cu(mpbi)2Cl2(H2O) have been synthesized and characterized by conductivity and magnetic measurements as well as by i.r., electronic and e.s.r. spectra. The ligands are bidentate donors through the pyridine and isoxazole nitrogen atoms. The CuLCl2 complexes exhibit spectral properties consistent with CuN2Cl2 chromophores differing in the degree of tetrahedral distortion, which is found to parallel the steric hindrance near the donor sites. Cu(mpbi)2 Cl2(H2O) is five-coordinate.

The copper(II), cobalt(II) and nickel(II) chloride and bromide complexes with the ligands 2-(2′-quinolyl)-benzimidazole (qbi), 2-(4′-methyl-2′-quinolyl)benzimidazole (mqbi), 2-(4′-methyl-8′-quinolyl)benzothiazole (m'q'bt) have been prepared and characterized by analytical methods, magnetic measurements as well as by electronic absorption, e.s.r. and far i.r. spectra. Complexes of various stoichiometries have been isolated, namely MLX2 (all cobalt complexes with exception of the bromide qbi complex; the chloride and bromide nickel m'q'bt and mq'bt complexes), ML2X2 (M=Co,L=qbi and X=Br; M=Ni, L=mqbi, X=Cl or Br, M=Ni, L=qbi, X=Cl) and ML3X2(M=Ni, L=qbi or mqbi, X=Br). The cobalt ion has a distorted tetrahedral N2X2 coordination in all the CoLX2 complexes, whereas Co(qbi)2Br2 is six-coordinate. The following conclusions may be drawn for the nickel complexes: in those with the 1∶1 metal-to-ligand molar ratio the metal ion is four-or five-coordinate; in those with the 1∶2 and 1∶3 ratios the metal ion is hexa-coordinate, being essentially bound to four nitrogen atoms with halogens, oxygens from water or methanol or nitrogen atoms (from the third ligand) occupying the axial positions.

Electron spin resonance studies have been carried out onN-ethylimidazole andN-propylimidazole 4 : 1 complexes of CuX2 salts (X = ClO 4 − , NO 3 − , , 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 NO 3 − 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).

Complexes of cobalt(II) and copper(II) with 5-amino-3,4-dimethylisoxazole (5-ADI) have been prepared and studied by means of magnetic susceptibility measurements, near and far i.r. spectra, electronic spectroscopy and, when possible, conductivity measurements. The 5-ADI generally behaves as bridging (Nring-, O- or Nring-, -NH2) ligand. All the complexes have an octahedral sterochemistry, except Co(5-ADI)2X2 (X = Cl, Br), Co2(5-ADI)7I4 which are tetrahedral and Cu(5-ADI)2 (ClO4)2 · 4 H2O which is square planar.

Cobalt(II) and nickel(II) halide complexes of the ligands 2-(2′-methyl-8′-quinolyl)benzoxazole (m′q′bo), 2-(2′-methyl8′quinolyl)benzimidazole (m′q′bi) and 2-(4′-methyl-8′-quinolyl)benzimidazole (mq′bi) were synthesized and characterized by analytical, thermogravimetric, conductivity and magnetic data, and i.r. and electronic spectra.

The Mn(PPO)nX2 complexes (where PPO is 2,5-diphenyloxazole, n = 1, 2 or 3 and X = Cl−, Br−, I− or SCN−) have been prepared from the corresponding metal salt with the ligand in methanolic solution or with the molten ligand in the appropriate reactant ratio and studied by chemical analysis, electronic and i.r. spectroscopy, magnetic and molar conductivity values at 25°. The complexes are generally nonconducting in DMF; they are high spin and hexacoordinated. The Mn(PPO)X2 complexes are high polymers with both ligand and anions bridging. The Mn(PPO)2X2 species are polymeric with PPO monodentate N-bonded and halogens and thiocyanates bridging bonded; the Mn(PPO)3X2 derivatives have monodentate N-bonded ligands whereas the halogens and thiocyanates are terminal and bridging, respectively.

Complexes of the type M(4-ADI)nX2 · mH2O (where 4-ADI = 4-amino-3,5-dimethylisoxazole; n = 1–4; X = Cl, Br, I, SCN, ClO4; m = 1–4) have been studied by i.r. and electronic spectroscopy, magnetic and conductivity measurements. The ligand behaves as a monodentate -NH2 bonded species in monomeric complexes, but as a bridging ligand-NH2 and -N(ring) bonded species in polymeric complexes. All the compounds have an octahedral stereochemistry, except Co(4-ADI)2X2 (X = Cl, Br, I) complexes, which are tetrahedral.

Cobalt(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.

We have synthesized and characterized halocuprate(II) complexes with isoxazolium and imidazolium derivatives. The compounds are of three types: a) Cu(LH)X3 · n H2O where L=isoxazole (isox), 3,5-diMeisox, or 5-amino-3,4-diMeisox (5-ADI); X=Cl or Br; n=1–2; b) (LH)2CuCl4 where L=5-ADI, N-ethylimidazole (N-EtIm) or N-PropIm; c) (3-AMIH)2Cu2X6 where 3-AMI=3-amino-5-methylisox; X= Cl or Br. Complexes (a) seem to be zwitterions with an oxygenbonded ligand and approximately tetrahedral structure; compounds (b) are distorted tetrahedral, nearly square planar; derivatives (c) are polymeric or dimeric with near square planar geometry.

Palladium(II) and platinum(II) complexes [MLX2], where L=2-(4′-methyl-2′-pyridyl)benzimidazole (mpbi), 2-(4′-methyl-2′-pyridyl)benzoxazole (mpbo), 2-(4′-methyl-2′-quinolyl)benzoxazole (mpbo), 2-(4′-methyl-8′-quinolyl)benzoxazole (mq'bo), X=Cl. Br, together with M(mqbo)2Br2 and Pt2(mpbt)Cl4, where mpbt=2-(4′-methyl-2′-pyridyl)benzthiazole, have been synthesized and characterized by conductivity and magnetic measurements as well as by i.r. and electronic spectra. The ligands are bidentate chelates through the pyridine or quinoline and isoxazole or imidazole nitrogen atoms. The [MLX2] derivatives arecis, square planar.

Complexes of chromium(III) with 2,5-diphenyloxazole (PPO) of general formula Cr(PPO)nX3·m H2O, where X=Cl−, Br−, I− or NO 3 su− ; n=1–3 and m=0–6, have been prepared and studied by spectroscopic and magnetic methods and by molar conductivity measurements. All the complexes seem to be hexacoordinated, generally with monodentate N-bonded ligand.

Copper(II) complexes [CuLX2], where L = 2-(2′-methyl-8′-quinolyl)benzoxazole, 2-(2′-methyl-8′-quinolyl)benzimidazole or 2-(4′-methyl-8′-quinolyl)-benzimidazole and X = Cl or Br, have been synthesized and characterized by conductivity and magnetic measurements, i.r., electronic and e.s.r. spectra.