Two tartratoborates with hybrid anionic groups from unusual condensation reactions.

Two novel tartratoborates, namely, K2 [(C4 H2 O6 )(B3 O4 H)](H2 O) (1) and KCu2 [(C4 H2 O6 )2 B](H2 O)2.5 (2), have been successfully synthesized by solvothermal reactions. They feature different kinds of structural types based on hybrid borate-tartrate motifs. The structure of compound 1 features a 3D network composed of novel [(C4 H2 O6 )2 (B3 O4 H)2 ]4- anionic groups interconnected by K+ cations. The [(C4 H2 O6 )2 (B3 O4 H)2 ]4- anion was formed by the condensation of two (B3 O8 H)6- groups and two tartrate anions, and such condensation reaction has never been reported previously. Compound 2 exhibits a novel 3D network structure in which 2D {Cu2 [(C4 H2 O6 )2 B](H2 O)2 }- layers are further interconnected via K+ ions. The [(C4 H2 O6 )2 B]5- anion was formed by the condensation of two tartrate anions with a B(OH)4 - unit. Magnetic measurements reveal a dominant antiferromagnetic interaction between neighboring Cu2+ ions in compound 2. Furthermore, UV-vis and infrared spectra and thermal analyses were also performed.