Diaquabis(Pyridine-2 2)-Copper(II) Squarate

Abstract

The title compound, [Cu(C<inf>6</inf>H<inf>6</inf>N<inf>2</inf>O) <inf>2</inf>(H<inf>2</inf>O)<inf>2</inf>](C<inf>4</inf>O<inf>4</inf>) [or Cu(pia)<inf>2</inf>(H<inf>2</inf>O)<inf>2</inf>.Sq, where pia is picolinamide or pyridine-2-carboxyamide, and Sq is the squarate dianion, (C<inf>4</inf>O <inf>4</inf>)2-], has been synthesized and the crystal structure determination is reported. The Cu2+ cation, located on a centre of symmetry, is coordinated by two symmetry-related aqua ligands together with a pair of symmetry-related bidentate pia molecules and exhibits elongated octahedral trans-[CuN<inf>2</inf>O<inf>4</inf>] coordination geometry. The unligated Sq dianion also lies on a crystallographic inversion centre. The squarate O atoms link the Sq ions to the metal complex via O-H⋯O and O-H⋯N hydrogen bonds. Intermolecular π-π and C-H⋯π interactions between the moieties also stabilize the crystal structure. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.