Showing papers by "Milan Melnik published in 2007"

Preparation, Structure, Spectral, and Magnetic Properties of Copper(II) Halogenonicotinates: Crystal and Molecular Structure of Tetrakis(μ-2-chloronicotinato-O,O′)-diaquadicopper(II)

Abstract: The characterization of the complexes [Cu2(2-Clnic)4(H2O)2] (1), [Cu(2,6-Cl2nic)2(H2O)2] (2) and [Cu(5-Brnic)2(H2O)2]n (3) (where 2-Clnic = 2-chloronicotinate, 2,6-Cl2nic = 2,6-dichloronicotinate or 5-Brnic = 5-bromonicotinate) was based on elemental analysis, IR, electronic and EPR spectra, and magnetic susceptibility. Complex 1 was also studied by X-ray analysis at 298 1a and 80 K 1b. The complex 1 contains a dinuclear Cu-acetate molecular structure in which the carboxyl groups of the 2-chloronicotinate ligands act as bridges and water molecules are at apical positions. The stereochemistry about Cu atom at both temperatures is typical for square pyramidal geometry with CuO4O chromophore. The Cu-Cu distance is 2.6513(8) and 2.6382(6) A for 1a and 1b, respectively. The Cu atoms are displaced by 0.2069(9) and 0.1973(7) A, respectively, from the plane containing four oxygen atoms bonded to the Cu atom toward the apical water molecules. Strong and weak hydrogen bonds as well as C–Cl···π interactions in the crystal structure are discussed as well. Both complexes, monomeric [Cu(2,6-Cl2nic)2(H2O)2] (2) and polymeric [Cu(5-Brnic)2(H2O)2]n (3), possess octahedral copper(II) stereochemistry with differing tetragonal distortions.

Aquabis(3-pyridylacrylato)-kappa O-2,O '; kappa O-bis(3-pyridylmethanol-kappa N)copper(II)

Abstract: In the title complex, [Cu(C8H6NO2)(2)(C6H7NO)(2)(H2O)], the Cu2+ ion has a highly distorted square-bipyramidal (4 + 1 + 1) coordination environment, and is bonded to three carboxylate O atoms of two 3-pyridylacrylate anions (monodentate and asymetric bidentate), two pyridine N atoms of 3-pyridyl-methanol ligands and one water O atom. O-(HO)-O-... and O-(HN)-N-... hydrogen bonds result in the formation of a two-dimensional layer structure.

Bis(2‐chlorobenzoato‐κO)bis(phenazone‐κO)zinc(II) 0.612‐hydrate

Abstract: The title compound, [Zn(C7H4ClO2)2(C11H12N2O)2].0.612H2O, is a mononuclear zinc(II) compound. The Zn atom lies on a crystallographic twofold rotation axis. It is coordinated in a distorted tetra­hedral arrangement by two O atoms of two phenazone mol­ecules and one carboxyl­ate O atom from each of two 2-chloro­benzoate anions. Intra­molecular O—H⋯O hydrogen bonds may be effective in the stabilization of the structure.

catena-Poly[[tetrakis(mu-propionato-kappa(2)O:O')dicopper(II)]-mu-3-pyridylmethanol-kappa(2)N:O-[bis(propionato-kappaO)bis(3-pyridylmethanol-kappaN)copper(II)]-mu-3-pyridylmethanol-kappaO:N].

Abstract: The title compound, [Cu(3)(C(3)H(5)O(2))(6)(C(6)H(7)NO)(4)](n), is composed of polymeric chains formed by alternating centrosymmetric Cu(2)(mu-CH(3)CH(2)CO(2))(4) and Cu(C(3)H(5)O(2))(2)(C(6)H(7)NO)(2) units. These elemental units are linked by two bridging 3-pyridylmethanol (3PM) ligands. The Cu(2)(mu-CH(3)CH(2)CO(2))(4) group presents a centrosymmetric tetrabridged structure with four syn-syn bridging propionate ligands to which two 3PM molecules are bonded (through N), occupying the apical positions of each square-pyramidal polyhedron around the Cu(II) ions. The remaining mononuclear group is centred around a third Cu(II) ion, which lies on a symmetry centre and is bound to two monodentate propionate groups (through O), two monodentate 3PM molecules (through N) and two bridging 3PM molecules (through O), thus completing a square-bipyramidal CuO(2)N(2)O(2) coordination.

Crystal and Molecular Structure of Polymeric {Νa(μ-ΟΗ2)2 (Maleinate-O)(H20)}n

Abstract: The crystal and molecular structure of polymeric Na(maleinate)(H20)3 has been determined by X-ray crystallography. The white complex crystallizes in triclinic system, space group P-l , with lattice parameters a = 5.954(1) A , b = 6.398(1) A, c = 11.250(2) Α, α = 104.18(3)°, ß = 91.56(3)°, γ = 100.22(3)° and Ζ = 2 at 293(2) Κ. The coordination geometry about each Na(I) atom is approximately octahedral, formed by five oxygen atoms of water molecules and one oxygen atom of maleinate monoanion. Two pairs of Ο atoms of water molecules serve as double bridges between Na(I) atoms, forming an infinite chain running along the a axis. The mean Na.. .Na separation of 3.49 A excludes a direct bond. There are either two dimensional hydrogen bonding networks which are discussed.

Stereochemistry of Platinum Organometallics

Abstract: The organometallic chemistry of platinum covers a huge field, as shown by a recent survey covering the crys- tallographic and structural data of almost one thousand organometallic derivatives. About nine percent of those deriva- tives exist as isomers and are summarized in this review and include distortion (90 %), cis - trans (6%) and ligand isomer- ism (4%). These are discussed in terms of the coordination about the platinum atom, and correlations are drawn between donor atom, bond length and interbond angles, with attention to any trans - effect. Distortion isomers, differing only by degree of distortion in Pt-L bond lengths and L- Pt -L bond angles, are the most nu- merous. They are also spread over a wider range of oxidation states of platinum, (zero, +1, +2, +4, mixed valence +1 plus +2 and +2 plus +4), compared to cis-trans and ligand isomerism in which only +2 is found.

Isomers in the Chemistry of Lead Compounds

Abstract: Chemistry of lead compounds covers a wide field, as shown by a recent survey covering the crystallographic and structural data of almost one thousand derivatievs. About 7 % of these derivatives exist as isomers and are summarised in this review. Included are distortion (60 %), ligand (20 %), coordination (12 %) and polymerisation (8 %) isomerism. These are discussed in terms of coordination about the lead atom, and correlations are drawn between donor atom, bond lengths and interbond angles. Distortion isomers, differing only by degree of distortion in Pb L and L-Pb-L angles, are the most common. Distortion and ligand isomerism spread over a wider range of oxidation state of lead + 2 (most common), + 3 and + 4, than coordination number and polymerisation isomerism ( + 2 only).

Bis(2-chlorobenzoato-κ2O,O′)bis[methylN-(3-pyridyl)carbamato-κN]zinc(II)

Abstract: In the title compound, [Zn(C7H4ClO2)2(C7H8N2O2)2], the ZnII ion is coordinated by two N atoms from two methyl N-(3-pyrid­yl)carbamate ligands and four O atoms from two bidentate 2-chloro­benzoate anions in a pseudo-octa­hedral geometry. The Zn—O distances are in the range 2.0484 (16)–2.380 (2) A, and the Zn—N distance is 2.1012 (18) A. The mol­ecules are linked into a chain along the c axis by N—H⋯O and C—H⋯Cl hydrogen bonds.

Innersphere transformations of pyridine-2-carbonitrile mediated by copper(II), cobalt(II) and nickel(II). Crystal structures of bis (nitrato)- bis ( N -2-hydroxyethyl- pyridine-2-carboxamidine- N,N ′)copper(II) and bromo-bis( N -3-hydroxy-propylpyridine-2-carboxamidine- N,N ′)copper(II) bromide

Abstract: Condensation of pyridine-2-carbonitrile (2-CNpy) with 2-aminoethanol (L1) or 1-amino-3-propanol (L2) in alcohol solutions of CuX2 (X = , , Cl− and Br−) proceeds readily under mild conditions to form stable solid complexes [Cu(NO3)2(amL1-NH)2], [Cu(amL1-NH)2](ClO4)2, [Cu(amL2-NH)2](ClO4)2, [CuCl2(amL2-NH2)] · H2O, [CuCl2(amL2-NH)2] and [CuBr(amL2-NH)2]Br, which contain the imino form of N-2-hydroxyethylpyridine-2-carboxamidine (amL1-NH) and imino or amino forms of N-3-hydroxypropylpyridine-2-carboxamidine (amL2-NH or amL2-NH2). Crystal structures of [Cu(NO3)2(N-2-hydroxyethyl-pyridine-2-carboxamidine-N,N′)2] and [CuBr(N-3-hydroxypropylpyridine-2-carboxamidine-N,N′)2]Br and IR data confirm bidentate N,N-coordination of N-hydroxyalkylpyridine-2-carboxamidines (via the nitrogen atom of the pyridine ring as well as the nitrogen atom of the terminal imino group). The structure of [Cu(NO3)2(amL1-NH)2] consists of well-separated centrosymmetrical Cu(amL1-NH)2(NO3)2 entities, including two independent kinds of mo...