Juan Server-Carrió

Cinoxacin complexes with divalent metal ions. Spectroscopic characterization. Crystal structure of a new dinuclear Cd(II) complex having two chelate-bridging carboxylate groups. Antibacterial studies

Several cinoxacin (HCx) complexes with divalent metal ions have been prepared and characterized by spectroscopic techniques. The crystal structure of [Cd2(Cx)4(H2O)2].10H2O has been determined by X-ray diffraction. The complex is triclinic, space group P1 with unit-cell dimensions: a = 10.412(2), b = 11.119(2), c = 13.143(6)A, chi== 76.78(4) degrees, beta = 74.59(3) degrees, gamma = 77.12(3) degrees, V = 1406.0(8) A3. In this complex each cadmium atom is heptacoordinated: the metal environment is formed by two Oketo and two Ocarbox atoms from two different cinoxacinate monoanions, two carboxylate oxygen atoms from a third cinoxacinate ligand and by one water oxygen atom on the seventh position. Two of the cinoxacinate ions act as tridentate chelate and bridging ligands and the other one as a bidentate chelate ligand. In the bridging monoanions the carboxylate group is behaving as a chelate ligand. All the complexes were screened for their activity against several bacteria, showing activity similar to that of cinoxacin. Additionally, the number of bacteria killed after 3 h of incubation with cinoxacin, [Cu(Cx)2].2H2O and [Co(Cx)3]Na.10H2O complexes was determined against E. coli ATCC 25922; the copper compound presents paradoxical effect which has been described and related to the mechanism of action of quinolones.

Potentiometric and spectroscopic studies of transition-metal ions complexes with a quinolone derivative (cinoxacin). Crystal structures of new Cu(II) and Ni(II) cinoxacin complexes

Abstract The interaction of cobalt(II), nickel(II), copper(II), and zinc(II) with Cinoxacin (HCx = 1-ethyl-1,4-dihydro-4-oxo(1,3)dioxolo(4,5-g)cinnoline-3-carboxylic acid), a 4-quinolone derivative, has been studied at metal/ligand ratios of 1:1-1:3 by means of pH-metric, spectrophotometric, and ESR methods. The formation constants have been determined and the stereochemistry for the metal ions in the species present in aqueous solutions (at 37 ± 0.1°C and I = 0.1 mol dm −3 NaCl) is discussed. In all the studied systems, complexes with different stoichiometric ratios, in which cinoxacin acts both as neutral and deprotonated ligand, are formed. The anomalous sequence of the stepwise stability constants observed for cobalt(II) and nickel(II) systems suggests changes in stereochemistry when CoCx 2 and NiCx 2 are formed. For zinc(II) this change has to be still more pronounced since a [ZnCx] + species has not been detected. For the Cu(II) system the sequence in the stepwise stability constants indicates the preferential formation of the [CuCx] + monocomplex. The crystal and molecular structure of new Cu(II) and Ni(II) complexes of cinoxacin have been investigated. The metal ion in [Cu(Cx) 2 H 2 O]·3H 2 O is five-coordinated and the complex crystallizes in the triclinic P 1 space group with a = 10.620(1), b = 11.358(1), c = 12.440(2) A , α = 78.25(1), β = 80.24(1), γ = 63.34(1)°, and Z = 2 . The complex [Ni(Cx) 2 -(DMSO) 2 ]·4H 2 O contains six-coordinated Ni(II) and crystallizes in the triclinic P 1 space group with a = 8.866(3), b = 9.141(1), c = 11.580(1) A , α = 69.301(9), β = 82.17(2), γ = 75.86(2)°, and Z = 1 .

Synthesis, crystal structure, spectroscopic characterisation and magnetic properties of [Cu2(BIBM)2(C2O4)2]·4H2O (BIBM=bis(2-imidazolyl)bis(methoxycarbonyl)methylmethane)

Abstract The structure and spectroscopic and magnetic properties of bis(μ-1,2,3-oxalato)bis[bis(2-imidazolyl)bis(methoxycarbonyl)methylmethane]dicopper(II) tetrahydrate are described. The compound is built of centrosymmetric neutral dimeric [Cu2(BIBM)2(C2O4)2] entities linked through hydrogen bonds involving water molecules and oxalate groups. In the dimeric unit the two centrosymmetrically related copper — which are involved in CuN2O2O2′ chromophores lying in an elongated octahedral environment — are bridged through the oxalate group which acts in a bidentate–monodentate (μ-1,2,3) fashion. 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=−0.35 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.

Coordination chemistry of sulfamethizole: crystal structures of [Cu(sulfamethizolate)2(py)2(OH2)]·H2O, [M(sulfamethizolate)2(py)2(OH2)2] [M=Co and Ni] and {Cu(sulfamethizolate)2(dmf)2}∞

Abstract The synthesis and characterisation of copper, cobalt, nickel and zinc compounds with sulfamethizole (4-amino-N-(5-methyl-1,3,4-thiadiazole-2-yl)sulfanilamide) (Hsmtz) are described. The first crystal structures of ternary sulfamethizole complexes are reported. The crystal structures of Cu(smtz)2(py)2(OH2)·H2O (1), M(smtz)2(py)2(OH2)2 [M=Co (2), Ni (3)] and {Cu(smtz)2(dmf)2}∞ (5) were determined by X-ray diffraction. The Cu(II) ion exhibits a square pyramidal geometry in complex 1, while in the other compounds the metal ion presents a distorted octahedral environment. In compounds 1, 2 and 3 the deprotonated sulfamethizole acts as monodentate ligand coordinating through the thiadiazole N atom and in compound 5 it behaves as a bridge linking two metal cations via the thiadiazole and the amino nitrogen atoms. The IR, electronic, EPR and thermal data are consistent with the crystal structures.

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 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.

Coordinating behaviour of 3-methyl[1,2,3]triazolo[1,5-a]pyridine (tzpy): crystal and molecular structure and electronic properties of [Cu(tzpy)2(ONO2)2(OH2)]

Abstract The crystal and molecular structure of [Cu(tzpy) 2 (ONO 2 ) 2 (OH 2 )] (tzpy=3-methyl[1,2,3]triazolo[1,5- a ]pyridine) has been determined by X-ray diffraction methods. The crystal structure is built up of discrete [Cu(tzpy) 2 (ONO 2 ) 2 (OH 2 )] entities linked through hydrogen bonds. The coordination geometry around the copper atom can be described as an elongated and strongly distorted octahedron displaying a 4+1+1* coordination mode (CuN 2 O 2 O′O″ chromophore), with one of the nitrato groups acting as bidentate and involved in a weak off-the- z -axis coordination. Spectroscopic properties are interpreted on the basis of the above stereochemistry.

COORDINATIVE VERSATILITY OF THE CARBONIC ANHYDRASE INHIBITOR BENZOLAMIDE IN ZINC AND COPPER MODEL COMPOUNDS

New benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) zinc(II) and copper(II) complexes with tris(2-benzimidazolyl-methylamine) (L) and ammonia are reported. The crystal structures of the Zn(II) complexes were determined. The [Zn(Hbz)L]ClO 4 · H 2 O compound crystallizes in the triclinic space group with a =11.006(1), b =14.777(2), c =14.918(2) A, α =114.30(1), β =98.90(1), γ =107.36(1)° and Z =2. In this compound the Zn(II) has a distorted trigonal bipyramidal geometry. The {[Zn 2 (bz) 2 (NH 3 ) 4 ] · 2H 2 O} ∞ crystallizes in the monoclinic space group C 2/ c with a =23.530(3), b =10.4124(11), c =15.428(2) A, β =110.591(9)° and Z =4. The metal centre is in a distorted tetrahedral [ZnN 4 ] environment. The benzolamide presents a different coordination behaviour in these complexes. In [Zn(Hbz)L]ClO 4 · H 2 O it acts as a monodentate ligand through the thiadiazole N atom contiguous to the deprotonated sulfonamido group, while in {[Zn 2 (bz) 2 (NH 3 ) 4 ] · 2H 2 O} ∞ it behaves as a bridge joining two Zn(II) ions via the N atom of the thiadiazole ring and the N atom of the free sulfonamido group. The Cu(Hbz)L(NO 3 ) complex was also obtained and characterized. The electronic properties and the EPR of the copper-doped zinc complexes showed that the copper(II) ion adopts a square pyramidal geometry. Also, for the Zn(II) complexes the interaction Zn–benzolamide has been studied using extended-Huckel molecular-orbital (EHMO) calculations.

Reaction of 3-Methylamino-1,2-diols with Dihalomethanes. Synthesis of Chiral 4-Substituted 3-Methyltetrahydro-1,3-oxazin-5-ols

Abstract Enantiomerically pure 4,5-disubstituted 3-methyltetrahydro-1,3-oxazines have been obtained by reaction of 3-methylamino-1,2-diols with dichloromethane by regioselective differentiation of hydroxyl groups.