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1

Molecular ribbons in the crystals of a new Cu(II) complex with pyrazine-2,3-dicarboxylate ligand

Ptasiewicz-Bąk H., Leciejewicz J.

Polish Journal of Chemistry

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1999

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vol. 73 nr 5

853-858

EN

The structure of diaquobis(m-trans hydrogen pyrazine-2,3-dicarboxylato N,O,O')copper(II) dihydrate crystals is polymeric. The coordination polyhedron around the Cu(II) ion is an elongated octahedron. The Cu(II) ion and two symmetry related pyrazine-2,3-dicarboxylate (2,3-PZDC) ligands are coplanar and form the basic unit of this structure. Each ligand coordinates the metal with one carboxylate oxygen atom [Cu-O(1) 1.957(3) A] and the nearest heteroring nitrogen atom [Cu-N(1) 2.000(3) A]. The second carboxylic group contributes one carbonyl oxygen atom that coordinates the Cu(II) ion in an adjacent unit [Cu-O(3) 2.414(4) A], giving rise to molecular ribbons composed of Cu(2,3-PZDC)2 units interconnected by oxygen atoms. The water molecules are involved in a system of hydrogen bonds operating between the ribbons.

2

Crystal and molecular structures of nickel(II) complexes with pyrazine-2,3-dicarboxylic and 3-aminopyrazine-2-carboxylic acids

Ptasiewicz-Bąk H., Leciejewicz J.

Polish Journal of Chemistry

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1999

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vol. 73 nr 4

717-725

EN

Crystals of diaquobis(trans hydrogen pyrazine-2,3-dicarboxylato N,O)niclel(II) - title compound I, contain monometric molecules. The nickel(II) ion is coordinated by two molecules of pyrazine-2,3-dicarboxylic acid, each donating its heteroring nitrogen [Ni-O 2.0485(15) A] and one oxygen atom, belonging to the nearest monodentate carboxylic group [Ni-O 2.0199(14) A]. Two water molecules [Ni-O 2.0914(17) A] complete the octahedral coordination around the central ion. The second carboxylic group and the heteroring nitrogen do not directly bond to the nickel(II) ion. Monometric molecules of the composition Ni(II)(APZA)2(H2))2-title compound II, have been also found in the crystals of diaquobis(trans 3-amino-2-pyrazinecarboxylato O,N)nickel(II) compound. The coordination of the Ni ion is octahedral. (N,O) bonding moieties of two ligand molecules [Ni-O 2.0395(12) A, Ni-N 2.0669(14) A] and the Ni ion are coplanar. The oxygen atoms donated by two water molecules [Ni-O 2.0656(14) A] constitue the vertices of the slightly elongated octahedron. The structures of both title compounds indicate a preference of nickel ion to form monometric molecules. The monometric molecules contain intramolecular hydrogen bonds. The stability of the crystals is maintained by a system of intermolecular hydrogen bonds.

3

Crystal and Molecular Structure of a Zn(II) Complex with Pyrazine-2,3-dicarboxylate Ligand

Ptasiewicz-Bąk H., Leciejewicz J.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 11

1887-1894

EN

The ribbons are interconnected by an extensive network of hydrogen bonds operating via the coordinated and solvate water molecules.

4

The crystal structure of strontium complex with 3-aminopyrazine-2-carboxylic acid

Leciejewicz J., Ptasiewicz-Bąk H., Zachara J.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 8

1994-1998

EN

In the crystals of trans-diaquobis(my-3-aminopyrazine-2-carboxylato-N,O,O,O)strontium(II) the Sr ion is eightfold coordinated: by two aminopyrazine (APZA) ligands via their (N,O) bonding moieties [Sr-O 2.5189(15) A, Sr-N 2.7280(18) A], two other carboxylate oxygen atoms donated by the adjacent APZA molecules [Sr-O 2.5989(16) A] bridging the Sr(APZA)2 units into molecular ribbons and two water molecules [Sr-O 2.5556(18) A]. The ribbons are interconnected by hydrogen bonds involving the water molecules and the carboxylate oxygens [O-H...O 2.71(1) A], as well as the amino group nitrogen atoms and the heteroring nitrogen atoms [N-H...N 3.08(1) A].

5

Polymeric crystal structure of trisaquo(my-pyrazine-2,3-dicarboxylato)strontium(II)

Ptasiewicz-Bąk H., Leciejewicz J.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 3

627-632

EN

Trisaquo(my-pyrazine-2,3-dicarboxylato)strontium(II), SrC6H8N2O7 crystals have been studied by X-ray diffraction. The strontium ion is coordinated by a heteroring nitrogen, Sr-N of 2.793 A, and one oxygen atom belonging to a monodentate carboxylic group, Sr-O of 2.583 A, situated close to this nitrogen atom. Two oxygen atoms of carboxylic groups belonging to adjacent complex molecules, Sr-O=2.647 A and 2.914 A, bridge them into ribbons. Each oxygen atom of the above group is also linked to the Sr ions belonging to adjacent ribbons, Sr-O=2.576 A and 2.620 A, forming molecular sheets, which are parallel to the (010) plane. Each Sr ion coordinates also three oxygen atoms of water molecules (the average distance is 2.669 A. Hydrogen bonds of 2.66(1)-2.84(1) A link the sheets into a 3-dimensional framework.

6

Monomeric molecules in the isostructural calcium(II) and strontium(II) complexes with pyrazine-2-carboxylic acid

Ptasiewicz-Bąk H., Ostrowski A., Leciejewicz J.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 8

2014-2023

EN

The crystals of cis-tetraquobis(pyrazine-2-carboxylato-O,N)calcium(II) contain monomeric molecules, in which the calcium ion has a distorted dodecahedral coordination, formed by four water molecules (mean Ca-O = 2.441 A), two oxygen atoms from monodentate carboxylic groups of two pyrazinic acid molecules (mean Ca-O = 2.458 A) and two nitrogen atoms located next to the above carboxylic groups (mean Ca-N = 2.619 A). In the crystals of cis-tetraquobis(pyrazine-2-carboxylato-O,N)strontium(II) the coordination of the Sr(2+) ion is identical with that of the calcium complex, the corresponding mean distances being Sr-O(water) 2.572 A, Sr-O 2.588 A, Sr-N 2.751 A. The monomeric molecules of both compounds are linked via a network of hydrogen bonds.