Bis(μ₃-barbiturato−O,O,O′)-(μ₂-aqua)- aqua-barium(II): crystal structure, spectroscopic and thermal properties

Abstract

A polymeric coordination compound, [Ba(H₂O) ₂(Hba)₂] (1) (H₂ba – barbituric acid, C₄H₄N₂O₃), was obtained. The structure of 1 was solved using powder X-ray diffraction methods. The Ba²⁺ ion in 1 formed a three-capped trigonal prism. The BaO₉ polyhedra, connected with each other by the edges and faces, formed a chain. Several 4- and 12-membered cycles due to the bridging μ₂-H₂O and bridging μ₃-Hba^– also formed implementing a 3-D polymer structure. The structures of 1 and other thiobarbiturate complexes were compared. The replacement of a S atom by an O atom in the heterocyclic ligand Htba⁻ (thiobarbiturate ion) of the compound Ba(H₂O)₂(Htba)₂ resulted in changes of the coordination number Ba(II) and supramolecular structure. The intermolecular hydrogen bonds O–H⋯O and N–H⋯O formed a 3-D net where pronounced 2-D layers of Hba^– ions could be found. A new topological net in 1 was observed. The IR and thermal stability were investigated.

Keywords:

• Barbituric acid
• barium
• coordination compound
• X-ray diffraction
• infrared spectroscopy
• thermal analysis

Acknowledgements

The study was carried out within the public task of the Ministry of Education and Science of the Russian Federation for research engineering of the Siberian Federal University in 2016 (project № 3049).