Related Experiment Video
Updated: Aug 18, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
trans-Diaquabis(5-carboxy-1H-imidazole-4-carboxylato-kappa2N3,O4)cobalt(II) 4,4'-bipyridine solvate
Yu Ling Wang1, Rong Cao, Wen Hua Bi
1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People's Republic of China. wy176@ms.fjirsm.ac.cn
Abstract:
In the title compound, [Co(C(5)H(3)N(2)O(4))(2)(H(2)O)(2)].C(10)H(8)N(2), the Co atom is trans-coordinated by two pairs of N and O atoms from two monoanionic 4,5-dicarboxyimidazole ligands, and by two O atoms from two coordinated water molecules, in a distorted octahedral geometry. The 4,4'-bipyridine solvent molecule is not involved in coordination but is linked by an N-H...N hydrogen bond to the neutral [Co(C(5)H(3)N(2)O(4))(2)(H(2)O)(2)] molecule. Both molecules are located on inversion centers. The crystal packing is stabilized by N-H...N and O-H...O hydrogen bonds, which produce a three-dimensional hydrogen-bonded network. Offset pi-pi stacking interactions between the pyridine rings of adjacent 4,4'-bipyridine molecules were observed, with a face-to-face distance of 3.345 (1) angstroms.
Related Concept Videos
Coordination Number and Geometry
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.

