Julia García-Lozano

Crystal and molecular structure and electronic properties of [Cu(bbimpy)(H2O)2(ONO2)](NO3)· H2O (bbimpy = 2,6-bis(2-benzimidazolyl)pyridine)

Abstract The crystal structure of the complex [Cu(bbimpy)(H2O)2(ONO2)](NO3)·H2O(bbimpy = 2,6-bis(2-benzimidazolyl)pyridine) has been determined by X-ray diffraction methods. It crystallises in the monoclinic space group P2 1 n , with Z = 4 in a cell of dimensions a = 13.350(1), b = 7.820(1), c = 21.484(1) A , β = 92.26(1)° . The structure is built up of [Cu(bbimpy)(H2O)2(ONO2)]+ cations, NO3− anions and crystal lattice water molecules, with a 4 + 1 + 1 pseudo-octahedral geometry for the CuN3OO′O″ chromophores. In the EPR spectrum exchange coupling between Cu(II) chromophores of different orientation is observed, and molecular g values, compatible with the crystallographic data, could be calculated.

Crystal and molecular structure and properties of the first characterized copper(II) one-dimensional polymer containing mepirizole [4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine]

The crystal and molecular structure of the complex [Cu(mpym)(H2O)(C4O4)]·2H2O [mpym = mepirizole = 4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine] has been determined by X-ray methods. It crystallizes in the orthorhombic space group Pbcn, with Z= 8, a= 18.592(3), b= 14.723(2) and c= 13.755(3)A, R= 0.053 and R′= 0.070 for 2697 reflections. The structure comprises infinite chains parallel to [001] built up of 1-bis(monodentate) squarate-O1O3 C4O4 anions bridging [Cu(mpym)(H2O)]2+ units. The copper(II) ions display distorted trigonal-bipyramidal geometry. Both electronic and ESR spectra are indicative of an essentially dz2 ground state for the CuII. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is discussed on the basis of the relative orientation of the co-ordination polyhedron around the metallic atom and the bridging ligand.

Crystal structure, spectroscopic characterisation and magnetic properties of [Cu(BIP)(N3)]·H2O (BIP=3,3-bis(2-imidazolyl)propionate), a copper(II) polymeric compound with asymmetrical μ-1,3-azido bridges

Abstract The structure and the spectroscopic and magnetic properties of [3,3-bis(2-imidazolyl)propionato]azidocopper(II) monohydrate are described. The compound is built of [Cu(BIP)N3] entities which are connected through carboxylate groups from the BIP molecules —which act as a tridentate ligand—and asymmetrical μ-1,3-azido bridges, leading to a polymeric sheet-like structure. The copper atom is involved in a CuN3ON′ chromophore and lies in a distorted square-pyramidal environment. Both electronic and EPR spectra are indicative of an essentially dx2−y2 ground state for the copper(II) ions. Magnetic susceptibility measurements in the range 1.8–200 K show very weak antiferromagnetic exchange between the copper(II) ions (2J=−0.48 cm−1). This feature is discussed on the basis of the relative orientation of the coordination polyhedron around the metal atom and the bridging network.

X-ray crystal structure and electronic properties of chlorobis(mepirizole)copper(II) tetrafluoroborate (mepirizole = 4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine)

Abstract The crystal structure of [Cu(mep)2Cl](BF4)[mep = 4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine] has been determined by X-ray diffraction. The crystal structure is built up of [Cu(mep)2Cl]+ cations and BF4− anions. The structure of the cation involves a five-coordinated CuN4Cl chromophore, with a stereochemistry near to a compressed trigonal bypyramid (TBP) but with a significant degree of distortion towards the square pyramidal (SP) topology. The EPR spectrum is indicative of a mixed dz2/dx2 − y2 ground state for the copper(II) ions, in agreement with the structural data.

Exchange interactions through hydrogen-bond bridges. Crystal structure, spectroscopic characterisation and magnetic properties of the complex [{Cu(en)}2(μ-egta)]·4H2O (H4egta = 3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedionic acid)

Abstract The structure and spectroscopic and magnetic properties of [{Cu(en)} 2 (μ-egta)]·4H 2 O (H 4 egta = 3,12-bis(carboxymethyl)-6–9-dio 3,12-diazatetradecanedioic acid) are described. The compound is built of centrosymmetric neutral dimeric {[Cu(en)} 2 (μ-egta)] entities linked through hydrogen bonds involving water molecules. -NH 2 groups and -CO 2 groups, affording a three-dimensional framework. The egta anion displays an opened-up structure acting as a bridging ligand between two copper atoms. The coordination geometry about the metal atoms can be viewed as 4 + 1 + 1 (CuN 3 OO′O″ chromophores). The EPR spectra are indicative of an essentially d v−v ground state for the copper(II) ions. Magnetic susceptibility measurements in the range 1.8–200 K show weak antiferromagnetic exchange interactions (2 J ≡ = 1.51(1) cm −1 . The observed behaviour is discussed based on the crystal structure and compared with that observed in the related compound {(Cu(H 2 O)} 2 (μ-egta)]·2H 2 O. From this study, the triatomic NH…O bridges between the dimeric [{Cu(en)} 2 (μ-egta)] units are thought to be the suitable pathway for the exchange interaction.

Stereochemistry of [Cu(Tridentate Ligand)2] entities. crystal and molecular structure and electronic properties of [Cu(tedpa)2](PF6)2 (tedpa = N,N,N′N′-tetraethyl pyridinedicarboxamide)

Abstract The crystal and molecular structure of [Cu(tedpa) 2 ](PF 6 ) 2 have been determined by X-ray diffraction methods. The compound is built up of cationic [Cu(tedpa) 2 ] 2+ and PF 6 groups. The coordination geometry about the copper atom can be described as an elongated and strongly distorted octahedron (CuN 2 O 3 O′ chromophore). The EPR powder spectrum is slightly orthorhombic and from the g values and the partially resolved hyperfine components some covalency and molecular parameters have been estimated. EPR single crystal experiments indicate that the g -tensor axes follow the molecular bonds. Copyright

Synthesis and Spectroscopic Characterisation of bis-Complexes of Cobalt(II), Nickel(II) and Copper(II) with N,N,N′N′-Tetraethylpyridinecarboxamide

Abstract Bis-complexes of Co(II), Ni(II) and Cu(II) with tedpa (N,N,N′N′-tetraethyl-pyridinedicarboxamide) having the general formula [M(tedpa)2]X2 (X = ClO4, PF6) have been synthesized and characterised by i.r., electronic and e.p.r. spectra. The spectroscopic results suggest that the tedpa acts in these compounds as tridentate ligand through two oxygen atoms and a nitrogen (from the pyridine ring) atom. A distorted octahedral environment (MN2O4 chromophores) for the metal atoms is inferred from the spectroscopic data.

STRUCTURAL, SPECTROSCOPIC AND MAGNETIC CHARACTERIZATION OF AQUABIS(CROTONATO)BIS(IMIDAZOLE)COPPER(II)

Abstract The X-ray crystal structure of [Cu(crot)2(im)2(H2O)] (crot = 2-butenoate(crotonate) anion ; im = imidazole) has been determined by X-ray diffraction methods. The compound is built of neutral [Cu(crot)2(im)2(H2O)] entities linked through hydrogen bonds involving water molecules and carboxylate groups to give a chain structure running along the b axis. The copper atom is involved in a CuN2O2O′ chromophore and lies in a distorted square-pyramidal environment. Both electronic and EPR spectra are indicative of an essentially dx2-y2 ground state for the copper(II) ions. No exchange coupling has been detected down to 4.2 K by means of magnetic susceptibility measurements. This feature is discussed on the basis of the relative orientation of the coordination polyhedron around the metal atom and the bridging network. Copyright

Interaction between metal ions and zwitterionic species. crystal and molecular structure and spectroscopic characterization of [Cu(mtpa)2(NO3)2l (mtpa[2-(3-METHYL-1,2,3-TRIAZOLO [1,5-a]PYRIDINIO)]ACETATE)

Abstract -The crystal and molecular structure of [Cu(mtpa)2(NO3)2] (mtpa[2-(3-methyl-1,2,3-triazolo[1,5-a]pyridinio)]acetate) have been determined by X-ray diffraction methods. The crystal structure is built up of discrete [Cu(mtpa)2(NO3)2] entities. The stereochemistry displayed by the copper atoms, which lie on symmetry centres, can be described as elongated rhombic octahedral (CuO2O2′O2″ chromophore), with bidentate nitrato groups involved in off-the-z-axis coordination. Spectroscopic properties are interpreted on the basis of the above stereochemistry.

Coordinating behaviour of a new pyridylhydrazone; tris-complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with 2-pyridylcarbaldehyde-N,N-dimethylhydrazone

SummaryThe preparation and characterization oftris-complexes of MnII, CoII, NiII, CuII and ZnII with a new pyridylhydrazone, 2-pyridylcarbaldehyde-N,N-dimethylhydrazone (pch), are described. In all the complexes pch behaves as a bidentate ligand binding through the pyridine and azomethyne nitrogen atoms. The complexes appear to be monomeric, high spin six-coordinate, and a distorted octahedral stereochemistry around the metal is suggested. The e.p.r. results for both CuII compounds indicate a mainly dx2−y2 ground state with a static Jahn-Teller distortion, whilst for the MnII complex the e.p.r. data indicates a very low symmetry for the MnN6 polyhedron.