M. T. do P. Gambardella

Synthesis and characterization of copper(II) complexes with a tridentate schiff base ligand derived from 5-chloro-2-hydroxyacetophenone and salicylhydrazide. X-ray structure of copper(II) (5-chloro-2-hydroxyacetophenone-salicylhydrazide) dimethylformamide

Abstract Two copper(II) complexes with the Schiff base derived from the condensation of 5-chloro-2- hydroxyacetophenone and salicylhydrazide have been prepared and characterized by means of IR, electronic and EPR spectroscopies and magnetic measurements. For Cu(II) (5-chloro-2-hydroxyacetophenonesalicylhydrazide) dimethylformamide, Cu(5Cl-OHA-SHZ) DMF, obtained by recrystallizing the anhydrous complex Cu(5Cl-OHA-SHZ) from dimethylformamide solution, the crystal structure was also determined. Crystals of Cu(5Cl-OHA-SHZ) DMF are triclinic, space group P 1 , with two molecules in a unit cell of dimensions: a = 8.012(2), b = 8.359(2), c = 13.906(1) A, α = 88.80(1), β = 88.48(1), γ = 82.01(1)°, and V= 918(1) A3. Refinement by full-matrix least-squares gave a final Rw = 0.058. In the mononuclear molecule the copper atom is bonded to three ONO donor atoms from the Schiff base ligand and to an oxygen atom from the DMF solvent molecule in a highly distorted square planar geometry. The EPR spectrum of this DMF coordinated complex has been interpreted in terms of the great deviation of the coordination geometry from the idealized square planar one. Cu(5Cl-OHA-SHZ) DMF was found to be a normal paramagnet. Variable temperature magnetic studies on the anhydrous compound suggest a dimeric structure with strong anti-ferromagnetic interactions (2J = −439 cm−1). The IR spectra are discussed in comparison with that of the free ligand.

Exchange interactions in carboxylate-bridged alternating chains of copper(II). Synthesis, crystal structure, spectroscopic and magnetic properties of catena-bis(N-salicylidene-l- methioninato)aquadicopper(II)

Abstract The synthesis, crystal structure, spectroscopic and magnetic properties are reported for catena-bis(N-salicylidene- l -methioninato)aquadicopper(II), Cu-SALENMET. The compound crystallizes in the orthorhombic space group P212121, with Z = 4. Lattice constants: a = 5.077(1), b = 13.229(1), c = 37.602(2) A, and V = 2525(8) A3. Least- squares refinement of 171 parameters led to a final R = 0.052 for 1208 independent reflections having I > 3σ(I). The asymmetric unit consists of two copper atoms and two SALENMET (N-salicylidene- l -methioninato) groups. Each metal atom is directly attached to a single SALENMET group. The first of the two copper atoms has a (4+2) tetragonally elongated coordination geometry. The SALENMET group directly attached to it and the oxygen atom of a coordinated water molecule occupy four of the coordination sites. The coordination sphere is completed by two carboxylic oxygen atoms, one belongs to a SALENMET group of an adjacent (x−1, y, z translation) asymmetric unit and the other belongs to the SALENMET group which is directly attached to the other copper atom within the asymmetric unit. This second copper atom has a (4 + 1) tetragonally elongated square pyramidal coordination geometry. Three of the coordination sites are occupied by the SALENMET group directly attached to it, one of them by the last above mentioned carboxylic oxygen atom. In this way, this oxygen atom is coordinated to both copper atoms within the asymmetric unit and the two SALENMET groups become linked through a CuOCu bridge. The coordination sphere is completed by two carboxylic oxygen atoms which belong to SALENMET groups of an adjacent asymmetric unit (x−1, y, z translation). The crystal structure consists of discrete polymeric units generated only by translation along the crystallographic a axis. The polymeric units are built by bonds through adjacent asymmetric units as described above. Magnetic susceptibility data reveal antiferromagnetic interactions that may be described by the Heisenberg alternating-chain theory. The best fit of the magnetic susceptibility data yields value for the exchange coupling constant and alternation parameter, (J, α) of −62.9 cm−1 and 0.58, respectively.

trans-[2,6-Diacetylpyridine bis(thiosemicarbazone)(1–)]diphenyltin(IV) Chloride

The chelating properties of the pentadentate ligand 2,6-diacetylpyridine bis(thiosemicarbazone) hydrochloride, H2daptsc.HCl, have been investigated in a new organotin complex, [PhSnPh(Hdaptsc)]Cl {or [Sn(C 6 H 5 ) 2 (C 11 H 14 N 7 S 2 )]Cl}. The structure determination revealed a monocationic complex consisting of a heptacoordinated Sn IV in a distorted pentagonal-bipyramidal geometry, with the thiosemicarbazone derivative acting as a pentadentate species at the equatorial plane and two phenyl groups at trans positions. The chloride acts as a counterion. 119 Sn Mossbauer measurements showed that the isomer shift and the quadrupole splitting are consistent with structural interpretation.

Ethyl 2-[(E)-5-chloro-2-hydroxy-4-nitrophenylazo]-3-(E)-amino-2-butenoate

The title molecule, C 12 H 13 ClN 4 O 5 , has two intramolecular hydrogen bonds (O1-H11...N3 and N4-H42...N2) and π-electron delocalization in the azoen-amine group. Adjacent molecules in the crystal are linked through N-H...O hydrogen bonds and this results in an infinite chain structure.

catena -Poly[ cis -dichloro- trans -dimethyltin(IV)-μ- meso -1,2-bis(phenylsulfinyl)ethane- O : O ']

The structure of the title compound, [SnCl2(CH3)2(C8H18O2S2)]n has been determined and revealed the occurrence of infinite chains of tin complexes bridged by disulfoxide derivatives. The SnIV atom is hexacoordinate in a distorted octahedral environment, with Cl atoms at distances of 2.521 (1) and 2.515 (1) A, and methyl carbanions at distances of 2.110 (4) and 2.111 (4) A. Two different disulfoxide groups, with Sn-O distances of 2.316 (3) and 2.320 (3) A, complete the coordination. NMR spectroscopy indicated the occurrence of discrete binuclear molecules in solution.

1:1 Complex Formed by 2-Picoline N-Oxide and 4-Nitrophenol

The 2-picoline N-oxide and 4-nitrophenol moieties in the title complex, C 6 H 7 NO.C 6 H 5 NO 3 , are held together by an intermolecular O-H...CN hydrogen bond. This crystal structure exhibits partial overlap between the rings of the molecules, in the [110] direction. The complex formed may be described by two planes which contain the 2-picoline N-oxide and 4-nitrophenol molecules, respectively.

1,3-Dimethylisoguanine trihydrate

The title compound, isolated from the marine sponge Amphimedon viridis, crystallizes with three molecules of water, C 7 H 9 N 5 O.3H 2 O. The water molecules are involved in four hydrogen bonds with 1,3-dimethyl-isoguanine, having N...O distances 3.010 (3), 2.857 (3), 2.762(3) and 2.810(3)A. The molecules are linked together through four water-water hydrogen bonds, having O...O distances 2.812(3), 2.739(2), 2.784(3) and 2.796 (3) A.

2:1 Complex of 3-picoline N-oxide and hydroquinone

The title system, 2C 6 H 7 NO.C 6 H 6 O 2 , belongs to a series of molecular complexes formed from 3-picoline N-oxide and diverse hydrogen-bond donors. The molecular complex owes its formation to a hydrogen bond between the O atom of the N-oxide group of each 3-picoline N-oxide molecule and the O atom of an OH group of the hydroquinone molecule. The complex has a dihedral angle of 48.16 (5)° between the aromatic rings and exhibits overlap between the hydroquinone and 3-picoline N-oxide molecules in the [001] direction. The structural characteristics of the title complex are compared with those of similar systems.

Bis{[2,6-diacetylpyridine bis(2-furoylhydrazone)(1–)]dimethyltin(IV)}trans-Tetrachlorodi-methylstannate(IV)

The structure of the title compound, [Sn(CH3)2(C19H16O4N5)]2[SnCl4(CH3)2], revealed the presence of two complexes. One is monocationic and consists of a heptacoordinated SnIV atom in a distorted pentagonal-bipyramidal geometry, with an aroylhydrazone ligand acting as a pentadentate species in the equatorial plane and two methyl groups in axial positions. The other complex is dianionic and has an hexacoordinated SnIV atom at the origin.

The 1:1 Complex Formed by 3-Picoline N-Oxide and p-Toluic Acid

The title co-crystal, C6H7NO.C7H5ClO2, belongs to a series of molecular complexes based on the N—O group and was studied in order to establish its possible nonlinear optical behaviour. The 2-picoline N-oxide and 3-chlorobenzoic acid moieties are held together by an intermolecular hydrogen bond between the N—O and O—H groups. This system shows a transparency in the visible region of spectra.