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.

Poly[di-μ-aqua-di-aqua-bis-(μ7-oxalato-κ(9) O (1):O (1):O (1),O (2):O (2):O (2'):O (2'),O (1'):O (1'))calciumdicaesium].

In the title compound, [CaCs2(C2O4)2(H2O)4] n , the Ca(2+) ion, lying on a twofold rotation axis, is coordinated by four O atoms from two oxalate ligands and two bridging water mol-ecules in an octa-hedral geometry. The Cs(+) ion is coordinated by seven O atoms from six oxalate ligands, one bridging water and one terminal water mol-ecule. The oxalate ligand displays a scarce high denticity.

Poly[diaquadi-μ6-oxalato-μ5-oxalato-chromium(III)rubidium(I)]: a new supramolecular isomer.

The title compound, [CrRb(C(2)O(4))(2)(H(2)O)(2)](n), obtained under hydrothermal conditions and investigated structurally at 100 K, is a three-dimensional supramolecular isomer of the layered structure compound studied at room temperature. This novel polymer is built up from crosslinked heterobimetallic units. The linkage of alternating edge- and vertex-shared RbO(7)(H(2)O)(2) and CrO(4)(H(2)O)(2) polyhedra running along three different directions gives a dense packing.