Synthesis, crystal structure, spectroscopic investigations, thermal behavior and DFT calculations of pentacarbonyl(2-methylpyrazine)chromium(0).

Pentacarbonyl(2-methylpyrazine)chromium(0) [Cr(CO)(5)(2mpyz)], complex was isolated from its n-hexane solution as orange plate-like crystals which were characterized by IR, NMR spectroscopies and X-ray crystallography. The crystallographic results show that the complex was crystallized in the monoclinic system with the unit cell parameters of a=7.176 (5), b=12.045 (3), c=14.461 (3)Å, ß=90.44 (3)° and space group 2/M. The single crystal structure of the complex shows the bonding of chromium metal to 2-methylpyrazine through the less sterically hindered nitrogen-4 lone pair. The pyrazine ring plane makes an angle of 179.58° (19) with COCrN bond axis. The four carbonyl groups are slightly bent away from pyrazine with the angle of 91.28° (17) for C(5)CrN1 bond axis. The DFT calculations run out using the Gaussian 03 PC program show good agreement with the experimental results. The thermal properties of the complex were also investigated by differential thermal analysis and thermogravimetry techniques.

Poly[µ-aqua-diaqua-(µ(2)-pyrazine-2,3-dicarboxyl-ato)dilithium(I)].

The asymmetric unit of the title compound, [Li(2)(C(6)H(2)N(2)O(4))(H(2)O)(3)](n), consists of two independent Li(+) cations, one pyrazine-2,3-dicarboxyl-ate dianion and three water mol-ecules. One of the Li(+) cations has a distorted tetra-hedral geometry, coordinated by one of the carboxyl-ate O atoms of the pyrazine-2,3-dicarboxyl-ate ligand and three O atoms from three water mol-ecules, whereas the other Li(+) cation has a distorted trigonal-bipyramidal geometry, coordinated by a carboxyl-ate O atom of a symmetry-related pyrazine-2,3-dicarboxyl-ate ligand, two water mol-ecules and a chelating pyrazine-2,3-dicarboxyl-ate ligand (by utilizing both N and O atoms) of an adjacent mol-ecule. The synthesis of a hydrated polymeric dinuclear lithium complex formed with two pyrazine-2,3-dicarboxylic acid ligands has been reported previously [Tombul et al. (2008a ▶). Acta Cryst. E64, m491-m492]. By comparision to the complex reported here, the dinuclear complex formed with two pyrazine-2,3-dicarboxylic acid ligands differs in the coordination geometry of both Li atoms. The crystal structure further features O-H⋯O and O-H⋯N hydrogen-bonding inter-actions involving the water mol-ecules and carboxyl-ate O atoms.

catena-Poly[[diaqua-rubidium(I)](µ(2)-3-carboxy-pyrazine-2-carboxyl-ato)(µ(2)-pyrazine-2,3-dicarboxylic acid)].

The structural unit of the title compound, [Rb(C(6)H(3)N(2)O(4))(C(6)H(4)N(2)O(4))(H(2)O)(2)](n), consists of one rubidium cation, one hydrogen pyrazine-2,3-dicarboxyl-ate anion, one pyrazine-2,3-dicarboxylic acid mol-ecule and two water mol-ecules. This formulation is repeated twice in the asymmetric unit as the rubidium cation lies on an inversion centre. Each anion or acid mol-ecule is linked to two rubidium cations, while the rubidium cation has close contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each rubidium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid holds its H atom, which forms a hydrogen bond to a coordinated water mol-ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O-H⋯O hydrogen bond disordered over an inversion centre. The stabil-ization of the crystal structure is further assisted by O-H⋯O and O-H⋯N hydrogen-bonding inter-actions involving the water mol-ecules and carboxyl-ate O atoms.

Erratum: Poly[[diaqua-caesium(II)]bis-(µ(3)-3-carboxy-pyrazine-2-carboxyl-ato)]. Corrigendum.

Corrections are made to the formulation and scheme in Tombul, Güven & Büyükgüngör [Acta Cryst. (2007) E63, m1783-m1784].[This corrects the article DOI: 10.1107/S1600536807025536.].

1,4-Diferrocenylbutane-1,4-dione.

In the crystal structure of the title compound, [Fe(2)(C(5)H(5))(2)(C(14)H(12)O(2))], each carbonyl group is coplanar with the adjacent cyclo-penta-dienyl ring, thus maximizing the π-orbital overlap and electronic inter-actions between the groups. In the crystal structure, there are inter- and intra-molecular C-H⋯O contacts.

Poly[triaquabis-(µ(2)-3-carboxy-pyrazine-2-carboxyl-ato)dilithium(I)].

In the title compound, [Li(2)(C(6)H(3)N(2)O(4))(2)(H(2)O)(3)](n), the coordination number for both independent Li(+) cations is five. One of the Li(+) ions has a distorted trigonal-bipyramidal geometry, coordinated by one of the carboxyl O atoms of a 3-carboxy-pyrazine-2-carboxyl-ate ligand, two O atoms from two water mol-ecules, and an N and a carboxyl-ate O atom of a second 3-carboxy-pyrazine-2-carboxyl-ate ligand. The other Li(+) ion also has a distorted trigonal-bipyramidal geometry, coordinated by one water mol-ecule and two 3-carboxy-pyrazine-2-carboxyl-ate ligands through an N and a carboxyl-ate O atom from each. One of the carboxyl groups of the two ligands takes part in an intra-molecular O-H⋯O hydrogen bond. The stabilization of the crystal structure is further assisted by O-H⋯O, O-H⋯N and C-H⋯O hydrogen-bonding inter-actions involving the water mol-ecules and carboxyl-ate O atoms.

Dipotassium maleate with boric acid.

In the title compound, poly[(mu3-boric acid)-mu4-maleato-dipotassium], [K2(C(4)H(2)O(4)){B(OH)3}]n, there are two independent K+ cations, one bonded to seven O atoms (three from boric acid and four from maleate), and the other eight-coordinate via three boric acid and four maleate O atoms and a weak eta(1)-type coordination to the C=C bond of the maleate central C atoms. Hydrogen bonding links the boric acid ligands and maleate dianions, completing the packing structure.

Poly[diaqua(µ(2)-3-carboxypyrazine-2-carboxylato)(µ(2)-pyrazine-2,3-dicarboxylic acid)potassium(I)].

The structural unit of the title compound, [K(C(6)H(3)N(2)O(4))(C(6)H(4)N(2)O(4))(H(2)O)(2)](n), consists of one potassium cation, one hydrogen pyrazine-2,3-dicarboxyl-ate anion, one pyrazine-2,3-dicarboxylic acid mol-ecule and two water mol-ecules; this is twice the asymmetric unit, since the potassium cation lies on an inversion centre. Each anion or acid mol-ecule is linked to two potassium cations, while the potassium cation has contacts to four symmetry-equivalent organic ligands, with two different coordination modes towards this cation. In addition, each potassium cation is coordinated by two water O atoms, raising the coordination number to eight. One of the carboxyl groups of the acid retains its H atom, which forms a hydrogen bond to a coordinated water mol-ecule. The other carboxyl group is deprotonated in half of the ligands and protonated in the other half, taking part in a strong O-H⋯O hydrogen bond disordered over an inversion centre. The stabilization of the crystal structure is further assisted by O-H⋯O and O-H⋯N hydrogen bonds in which water acts as the donor.

Dimethyl-ammonium bis-(3-oxidonaphthalene-2-carboxyl-ato)borate hemihydrate.

The title compound, C(2)H(8)N(+)·C(22)H(12)BO(6) (-)·0.5H(2)O, was synthesized under atmospheric conditions in the presence of dimethyl-formamide acting as a template. The structure is composed of [NH(2)(CH(3))(2)](+) cations, bis-(3-oxidonaphthalene-2-carboxyl-ato)borate anions and water mol-ecules. The water molecule lies on a twofold rotation axis. The stabilization of the crystal structure comes from electrostatic inter-actions and is assisted by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds between the layers.

Three 1,2,4-triazole derivatives containing substituted benzyl and benzylamino groups.

The title compounds, 4-benzylamino-3-(4-methylbenzyl)-1H-1,2,4-triazol-5(4H)-one, C17H18N4O, (I), 3-(4-methylbenzyl)-4-(4-methylbenzylamino)-1H-1,2,4-triazol-5(4H)-one, C18H20N4O, (II), and 3-(4-chlorobenzyl)-4-(4-methylbenzylamino)-1H-1,2,4-triazol-5(4H)-one, C17H17ClN4O, (III), were obtained from the corresponding Schiff base in the presence of diglyme and NaBH(4). Each compound contains a 1,2,4-triazole ring and two benzene rings, which are essentially planar. The molecules are linked by a combination of intermolecular N-H...O and N-H...N hydrogen bonds. Additionally, there is a weak pi-pi stacking interaction in (I), involving the benzene ring of the aminobenzyl group and the partially aromatic 1,2,4-triazole moiety, with a centroid-centroid distance of 3.7397 (10) A.

Crystal and molecular structures of 1-[3-(3,4-dimethoxyphenyl)-2-propenoyl]pyrrolidine.

The crystal structure of 1-[3-(3,4-dimethoxyphenyl)-2-propenoyl]pyrrolidine (C15H19NO3) (I) has been determined by X-ray analysis. It crystallizes orthorhombic space group Pbca with a = 24.295(3), b = 15.086(3), c = 7.552(3)A, V = 2768(1)A3, Z = 8, Dcalc = 1.254 g/cm3, mu = (Mo K(alpha)) = 0.87 cm(-1). The title compound has analgesic activity of cycloaliphatic amine part. The molecule is deviated from planar configuration.