A neutral macrocyclic binuclear copper(II) complex of the deprotonated form of the ligand<i>N,N</i>′-bis(pyridin-2-ylmethyl)pyrazine-2,3-dicarboxamide

The potentially bis-terdentate diamide ligand N,N'-bis[2-(2-pyridyl)ethyl]pyrazine-2,3-dicarboxamide (H(2)L(Et)) was structurally characterised. Potentiometric titrations revealed rather low pK(a) values for the deprotonation of the first amide group of H(2)L(Et) (14.2) and N,N'-bis(2-pyridylmethyl)pyrazine-2,3-dicarboxamide (H(2)L(Me), 13.1). Two tetranuclear copper(ii) square complexes of H(2)L(Et) with a paddle-wheel appearance, in which each ligand strand acts as a linear N(3)-NO hybrid terdentate-bidentate chelate, have been isolated and structurally characterised. Complex [Cu(II)(4)(H(2)L(Et))(2)(HL(Et))(2)](BF(4))(6).3MeCN.0.5H(2)O (.3MeCN.0.5H(2)O), with two nondeprotonated zwitterionic ligand strands and two monodeprotonated ligand strands, is formed in the 1 : 1 reaction of H(2)L(Et) and Cu(BF(4))(2).4H(2)O. It has a polymeric chain structure of tetranuclear subunits connected by N-H[dot dot dot]N hydrogen bonds. The same reaction carried out with one equivalent of base gives the related compound [Cu(II)(4)(HL(Et))(4)](BF(4))(4) (), with all four ligand strands monodeprotonated. It consists of isolated tetranuclear units. In both .3MeCN.0.5 H(2)O and the copper(ii) ions are in five-coordinate N(4)O environments but the degree of trigonality (tau) differs [.3MeCN.0.5H(2)O 0.14

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N,N′-Bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide

Wang

Yang

Lin

2016

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The title compound, C16H14N8O2, was prepared by a condensation reaction between the dimethyl ester of pyrazine-2,3-dicarboxylic acid and an excess of 2-(aminomethyl)pyrazine. The molecule is approximately V-shaped with the central pyrazine ring joined through amide linkages to two pyrazin-2-ylmethyl substituents. In the crystal, molecules are linked by N—H...O, N—H...N and C—H...O hydrogen bonds, forming a three-dimensional framework.

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A neutral macrocyclic binuclear copper(II) complex of the deprotonated form of the ligandN,N′-bis(pyridin-2-ylmethyl)pyrazine-2,3-dicarboxamide

Abstract: Key indicatorsSingle-crystal X-ray study T = 153 K Mean '(C±C) = 0.006 A Ê H-atom completeness 64% Disorder in solvent or counterion R factor = 0.045 wR factor = 0.114 Data-to-parameter ratio = 12.3For details of how these key indicators were automatically derived from the article, see

Cited by 4 publications

References 4 publications

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Six-membered ring systems: diazines and benzo derivatives

A [2 × 2] nickel(ii) grid and a copper(ii) square result from differing binding modes of a pyrazine-based diamide ligand

N,N′-Bis(pyrazin-2-ylmethyl)pyrazine-2,3-dicarboxamide

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