Examples of cation exchange in new ionic oxovanadium(IV) complexes with anions of cyclobutane-1,1-dicarboxylic acid

The results on the synthesis and study of the crystal structures of compounds based on anionic fragments {VO(Cbdc)(2)}(2-) formed by oxovanadium(IV) (vanadyl, VO2+) and two chelate-bound anions of cyclobutane-1,1-dicarboxylic acid (H(2)Cbdc = C4H6(COOH)(2)) are presented. The use of ammonium cation NH4 (+) as a counterion in the synthesis leads to the formation of the mononuclear complex (NH4)(2)[VO(Dbdc)(2)(H2O)] center dot 2H(2)O (I). In the case of K+ cation, compound [K-4(VO)(2)(Dbdc)(4)(H2O)(4)] (n) (II) with the 3D polymeric crystal structure is formed. The reaction of compound II with Mg(NO3)2 center dot 6H(2)O in an aqueous solution involves the partial substitution of K+ by Mg2+ cations to form 1D polymeric compound {[KMg0.5(VO)(Dbdc)(2)(H2O)(6.5)] center dot 3H(2)O} (n) (III), while a similar reaction of compound I does not afford the product of substitution of NH4 (+) by Mg2+ cations (CIF files CCDC 1551021-1551023 for compounds I-III, respectively).