6533b86ffe1ef96bd12ce642

RESEARCH PRODUCT

Syntheses, crystal structures and magnetic properties of new oxalato-, croconato- and squarato-containing copper(ii) complexesElectronic supplementary information (ESI) available: Stereoview of the structure of compound 2 (Fig. S1) and X-ray data as described in the text. See http://www.rsc.org/suppdata/nj/b3/b301212n/

subject

description

The preparation and magnetic investigation of five mononuclear copper(II) complexes of formula [Cu(pyim)(C2O4)(H2O)]·2H2O (1), [Cu(pyim)(C4O4)(H2O)2]·2H2O (2), Cu(pyim)(C5O5)·2.5H2O (3), [Cu(H2bim)(C2O4)(H2O)]·H2O (4) and [Cu(bpz)(C5O5)(H2O)] (5) [pyim=2-(2-pyridyl)imidazole, H2bim=2,2′-biimidazole, bpz=2,2′-bipyrazine, C2O42−=dianion of oxalic acid, C4O42−=dianion of squaric acid and C5O52−=dianion of croconic acid] are reported. The crystal structures of 1, 2, 4 and 5 have been determined. The copper atom has a distorted square pyramidal geometry in this family of complexes: two nitrogen atoms from the bidentate nitrogen donor [pyim (1 and 2), H2bim (4) and bpz (5)] and two oxygen atoms either from a chelating oxalate (1 and 4)/croconate (5) or from a monodentate squarate and a water molecule (2) build the basal plane whereas a water molecule fills the apical position (1, 2, 4 and 5). A semi-coordinated oxalate (1 and 4)/croconate (5) oxygen atom of a neighbouring molecule occupies the sixth coordination position, leading to centrosymmetric dinuclear units. Magnetic susceptibility measurements for 1–5 in the temperature range 2–290 K reveal the occurrence of weak intermolecular ferro- (1) and antiferromagnetic (2–5) interactions. The different strategies to use these neutral complexes as ligands in order to design polynuclear species are analyzed and discussed.