Marian Koman

COPPER(II) COORDINATION COMPOUNDS: CLASSIFICATION AND ANALYSIS OF CRYSTALLOGRAPHIC AND STRUCTURAL DATA III. DIMERIC COMPOUNDS

Abstract This review summarizes the data for over nine hundred dimeric Cu(II) coordination compounds. There are several types of the bridges, from which doubly bridges by far prevail. The most common ligands are O− and N− donors. From the stereochemical point of view, a square-pyramidal arrangement with different degrees of distortion about Cu(II), is the most common. Several relationships were found between the Cu-Cu distances and the Cu-L-Cu bridge angle and the type of bridging, between the intra-ligand L-Cu-L ring angles and coordination numbers.

Structure, spectral and magnetic behaviours of tetrakis(flufenamato)(caffeine)(aqua) di copper(II)—first example of two non-equivalent ligands at the apex

Abstract The crystal and molecular structure of the tetrakis(flufenamato)(caffeine)(aqua)(dicopper)(II) Cu 2 (fluf) 4 (caf)(H 2 O), was determined by direct methods and Fourier techniques. The two copper(II) atoms are bridged by four carboxylate group, with the apical ligand of a water molecule around Cu(1), and a caffeine molecule around Cu(2). The spectral and magnetic properties are also discussed.

METAL(II)-PROMOTED HYDROLYSIS OF PYRIDINE-2-CARBONITRILE TO PYRIDINE-2-CARBOXYLIC ACID. THE STRUCTURE OF CU(PYRIDINE-2-CARBOXYLATE)2.2H2O

Abstract Pyridine-2-carbonitrile (2-CNpy) undergoes Cu(II) or Co(II)-promoted hydrolysis to pyridine-2-carboxamide (piaH) and/or pyridine-2-carboxylic acid (pycH). The pathway of pycH formation depends on the presence of 2-amino-2-hydroxymethyl-1,3-propanediol (AL1) and on the central atom. In the absence of AL1, Co(II) or Cu(II) ions mediate piaH formation under mild reaction conditions in the first hydrolytic step. Cu(II) ions assist in piaH transformation to pycH by subsequent reflux. In the presence of AL1 and Co(II), a Co(II) complex containing pyoxaL1 (2-(2-pyridinyl)-4,4-bis(hydroxymethyl)-2-oxazoline) is formed in the first stage; subsequent decomposition of pyoxaL1 under the reflux yields pycH. Under similar conditions, no solid Cu(II) complex with pyoxaL1 can be isolated, but a Cu(II) complex with coordinated pyc− anions precipitates from the reaction mixture. The synthesis, spectral and magnetic properties of the complexes [Co(H2O)2 (piaH)2]Cl2, [Co(H2O)2(pyc)2] · 2H2O, [Cu(H2O)2(piaH)2]Cl2, [Cu(pyc)2] and [Cu(pyc)2] · 2H2O, including the structure determination of the latter one, are described.

Crystal and molecular structure of copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine)

Abstract Copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine) has been prepared and studied by the single crystal X-ray diffraction methods at 293(2) K. The compound crystallises in an orthorhombic system, space group Pbcn with a=8.196(2), b=13.124(3), c=25.612(5) A, and Z=8 (R=0.0374 for 3175 independent reflections with I>2σ(I)). Crystal structure analysis revealed that the copper(II) atom is surrounded by two non-equivalent terdentate ligands making up an ‘all-trans’ elongated octahedral arrangement. In consequence of Jahn–Teller distortion, considerable differences are found between the ligands for the pyridine-2,6-dicarboxylate anion with the values Cu–N 1.892(3), Cu–O 2.033(2) and 2.063(2) A, while for the 2,6-dimethanolpyridine ligand the values are 1.943(3), 2.341(3) and 2.433(2) A. There is a relationship between the Cu–L bond distances and the five-membered metallocyclic rings (O–Cu–N). The data are compared and discussed with those found in familiar CuL2 compounds with the CuO4N2 chromophore. Based on the molecular structure, the electronic, IR and EPR spectra are discussed.

Methanolysis of pyridine-2-carbonitrile in the coordination sphere of copper(II), cobalt(II) and nickel(II). The structure of [Ni(o-methylpyridine-2-carboximidate)3]Br2·4H2O

Abstract The reaction of pyridine-2-carbonitrile with copper(II), cobalt(II) and nickel(II) salts in methanol solution led to the formation of solid complexes containing O-methyl-pyridine-2-carboximidate as a ligand (L). Seventeen compounds with general formulae [MX2L], [MXL2]X, [MX2L2] or [ML3]X2, where X = Br−, Cl−, NCS−, ClO4− and M = CuII COII, NiII, have been obtained under various reaction conditions. Their stereochemistry and the mode of ligand coordination have been determined by spectral, magnetic and conductometric measurements. The crystal structure of [Ni(O-methylpyridine-2-carboximidate)3]Br2·4H2O was determined by X-ray diffraction techniques. The influence of the metal(II) atom on the composition and the stereochemistry of solid complexes is briefly discussed.

Copper(ii) halogenopropionates: low-temperature crystal and molecular structure of bis(2,2-dichloropropionato)-di(methyl-3-pyridylcarbamate)copper(ii) and bis(2-bromopropionato)-di (2-pyridylmethanol)copper(ii)

The synthesis and characterization of [Cu(CH3CCl2CO2)2(3-mpyc)2] (1) (3-mpyc = methyl-3-pyridylcarbamate) and [Cu(CH3CHBrCO2)2(2-pyme)2] (2) (2-pyme = 2-pyridylmethanol) are reported. The compounds under study were characterized by IR, electronic spectroscopy and X-ray analysis. The molecular structure of both Complexes 1 and 2 is mononuclear. The coordination environment around each copper(II) atom is a distorted tetragonal bipyramid.

Synthesis, spectral properties and crystal structures of copper(II) isonicotinates, first example of uncoordinated isonicotinates

Abstract The syntheses and crystal structures of solid complexes [Cu(en)2(H2O)2](isonic)2 and [Cu(isonic)(dien)(H2O)1.5]·0.5SO4·2.5H2O (en=ethylenediamine; dien=diethylenetriamine; isonic=isonicotinate) are reported. The crystal structure of [Cu(en)2(H2O)2](isonic)2 comprises [Cu(en)2(H2O)2]2+ cations and isonicotinate anions. To our knowledge, this is the first example which contains uncoordinated isonicotinate anions. The crystal structure of [Cu(isonic)(dien)(H2O)1.5]·0.5SO4·2.5H2O contains two cations [Cu(isonic)(dien)(H2O)]+ and [Cu(isonic)(dien)(H2O)2]+, sulfate anions and water molecules. The SO42− anion takes part in an extensive system of hydrogen bonds including both uncoordinated and partially also coordinated water molecules. Based on the molecular structure the electronic, IR and ESR spectra are discussed.

Structure and spectral study of copper(II) pyridinecarboxylates: crystal and molecular structure of trans-diaqua-bis(N,N-diethylnicotinamide-N)bis(2-chloronicotinate-O)copper(II)

Abstract New copper(II) pyridinecarboxylate compounds of the composition [CuX2(Et2nia)2(H2O)2] (where X=2-methylthionicotinate (2-MeSnic), 2-chloronicotinate (2-Clnic), 2,6-dichloronicotinate (2,6-Cl2nic), isonicotinate (isonic) and Et2nia=N,N-diethylnicotinamide) have been prepared. All the [CuX2(Et2nia)2(H2O)2] compounds seem to possess octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of [Cu(2-Clnic)2(Et2nia)2(H2O)2] was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. The tetragonal plane is created by 2-chloronicotinate anions bonded to the copper(II) atom via the unidentate carboxylate oxygen atoms [Cu–O1=1.965(2) A] and the pyridine ring nitrogen atoms of the neutral ligand N,N-diethylnicotinamide [Cu–N1=2.015(2) A], whilst in axial positions are water molecules [Cu–O1w=2.503(2) A].

Spectral and magnetic properties and bio-activity of copper(II) clofibriates: Part I. Crystal and molecular structure of trans-Cu(clofibriate)2(nicotinamide)2

Abstract New copper(II) clofibriate (clof) Cu(clof)2 and its compounds of composition Cu(clof)2L2 (where L=nicotinamide (na) or ronicol (ron)) and Cu(clof)2–caffeine are reported. The characterizations were based on elemental analysis, electronic and EPR spectra, and magnetic susceptibility measurements over the temperature range 4.5–300 K. The crystal and molecular structure of Cu(clof)2(na)2 has been determined. The copper(II) atom is bonded in a trans square-planar arrangement by two N atoms of two nicotinamide molecules and one carboxylate oxygen atom from each of two clofibriate anions. The remaining two carboxylate oxygen atoms of the anions at the axial positions completed a tetragonal-bipyramidal geometry. On the basis of spectral and magnetic properties structures of the compounds were proposed. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi.

Self-assembly of hydrogen-bonded supramolecular structures of two copper(II) 2-bromobenzoate complexes with 4-pyridylmethanol and nicotinamide

The structures of [Cu(2-Brbz)2(4PM)2(H2O)] (1) and [Cu(2-Brbz)2(NIA)2] · 2H2O 2 [where 2-Brbz is the 2-bromobenzoate anion, 4-PM is the 4-pyridylmethanol and NIA is nicotinamide] have been determined by X-ray and characterized by EPR spectroscopy. The Cu2+ cation in 1 is coordinated by a pair of oxygens from monodentate 2-bromobenzoate anions by a pair of pyridine nitrogens from monodentate 4-pyridylmethanol ligands and finally by a water forming a tetragonal-pyramidal coordination polyhedron. The Cu2+ cation in 2 is coordinated by two pairs of oxygens from the asymmetric bidentate 2-bromobenzoate anions and by a pair of pyridine nitrogen atoms from the monodentate nicotinamide in trans positions, forming an extremely elongated bipyramid. The molecules of both complexes are linked by O–H ··· O, C–H ··· O and for 2 by N–H ··· O hydrogen bonds, which create three-dimensional hydrogen-bonding networks. EPR spectra of 1 and 2 are in agreement with X-ray data. Nicotinamide as well as 4-pyridylmethanol are suitable ligands for construction of hydrogen bonding coordination polymers.