Synthesis and analysis of a novel dinuclear bis(oxamate) type complex using [Co2(H2mpba)3]2- mesocate as building block

Use of Supramolecular Chemistry and Crystal Engineering concepts for solid-state structure formation is constantly increasing.1 The development of new synthetic strategies trying to control the molecular ordering of organic or metal−organic building blocks to obtain desirable materials with interesting properties has been employed to the self-assembly of new compounds.1-2 Therefore, in the present work a new compound of formula [Co2(H2mpba)3][Co(H2O)5(CH3OH)]2DMSO2H2O (1) was prepared by reacting Co2+ ions and the H2mpba2- dianion through the in situ methodology in methanol/dmso mixture. It is well known that the crystallization process is very important in order to get a better understanding of the crystal assembly and therefore, we investigate the solvent and cobalt(II) ion roles in the desired-crystal growing. The analysis by CHN, IR, TG/DTA indicated the formation of 1. Analysis of the IR spectrum reveals N-H at 3232 cm‒1, which confirms the partial deprotonation of the H4mpba preligand, as well as bands of the carboxylate portion and solvent molecules. TG/DTA curves are in according with the studies by single crystal X-ray diffraction, which show two independent crystallography cobalt(II) centers coordinated to three (H2mpba)2- ligands (see Figure 1) and a third cobalt(II) ion coordinated to five water molecules and one methanol molecule forming the [Co(H2O)5(CH3OH)]2+ complex. Thus, for the first time, an anionic dinuclear unit [Co2(mpba)3]2- is stabilized by another cationic coordination complex, as shown in the crystal structure exhibited in Figure 2.