engleski

Effect of N-donor Ancillary Ligands on the Structural Properties of the Heterometallic [CuCr] Complexes

Enormous efforts are made in synthesizing of new heterometallic coordination polymers of one-, two-, and threedimensionl structures. Incorporation of both organic and inorganic components in these compounds has created a new dimension in searching for functional materials that have desired structures and properties. The chemistry of oxalate-containing complexes has become an active area of research – the oxalate moiety, C2O42−, acts as a linker between metal centres with various possibilities of bridging modes. A property of oxalate ions that has been of specific interest is their ability to mediate electronic effects between paramagnetic metal ions. A frequently used approach for the synthesis of oxalate-based polynuclear coordination systems consists in using mononuclear anionic oxalate complexes as ligands towards other transition-metal complex cations. The introduction of organic ligands containing N-donors into the metal–oxalate systems further stabilizes their solid-state structures. Weak non-covalent interactions such as π-stacking and hydrogen bonding may adjust the dimensionality and lead to new topologies and desired functions of these supramolecular assemblies. Applying the layering technique, the turquoise stick-like crystals of oxalate-bridged compounds {; ; ; ; [KCrCu2(µ-C2O4)4(bpy)2]·H2O}; ; ; ; n (1) have been grown from the reaction of an aqueous solution of K3[Cr(C2O4)3]·3H2O and methanol solution of CuCl2·H2O and 2, 2'-bipyridine (bpy). Interestingly, in this complex three different bridging modes of oxalate ligands are observed. The change of aromatic N-donor ligand from bpy to 1, 10-phenanthroline (phen) in the same reaction mixture, influenced greatly the reaction outcome – yellow polyhedra of formula {; ; ; ; [Cu2(µ-C2O4)(phen)2(µ-Cr2O7)]}; ; ; ; n (2), containing, beside oxalate-bridge units, bridging Cr2O72– anions. Using tridentate 2, 2′:6′, 2′′-terpyridine (terpy) instead of bidentate ligands in similar procedure, green prismatic crystals of hetrometallic chloro-bridged complex salt [Cu4(µ-Cl)3Cl2(terpy)4][Cr(C2O4)3]·9H2O (3) have been isolated.

Heterometallic ; Oxalate-Bridged ; Single-Crystal X-Ray Diffraction

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