ACr(CO)(HO) (A = Li or Na): two new coordination polymers of low dimensionality with different hydrogen-bond networks.

Single crystals of two new bimetallic oxalate compounds with the formula [ACr(CO)(HO)] (A = Li or Na), namely catena-poly[[diaqualithium(I)]-μ-oxalato-κO,O:O,O-[diaquachromium(III)]-μ-oxalato-κO,O:O,O], (I), and catena-poly[[diaquasodium(I)]-μ-oxalato-κO,O:O,O-[di-aquachromium(III)]-μ-oxalato-κO,O:O,O], (II), have been synthesized, characterized and their crystal structures elucidated by X-ray diffraction analysis and compared. The compounds crystallize in the monoclinic space group C2/m for (I) and in the triclinic space group P-1 for (II); however, they have somewhat similar features. In the asymmetric unit of (I), the Li and Cr atoms both have space-group-imposed 2/m site symmetry, while only half of the oxalate ligand is present and two independent water molecules lie on the mirror plane.

The new one-dimensional coordination polymer catena-poly[[diaquasodium(I)]-μ-oxalato-[diaquairon(III)]-μ-oxalato].

The oxalate dianion is one of the most studied ligands and is capable of bridging two or more metal centres and creating inorganic polymers based on the assembly of metal polyhedra with a wide variety of one-, two- or three-dimensional extended structures. Yellow single crystals of a new mixed-metal oxalate, namely catena-poly[[diaquasodium(I)]-μ-oxalato-κ(4)O(1),O(2):O(1'),O(2')-[diaquairon(III)]-μ-oxalato-κ(4)O(1),O(2):O(1'),O(2')], [NaFe(C2O4)2(H2O)4]n, have been synthesized and the crystal structure elucidated by X-ray diffraction analysis. The compound crystallizes in the noncentrosymmetric space group I41 (Z = 4).