Coordination Polymers Ca(II)–Cr(III) and Ba(II)–Cr(III) with Cyclobutane-1,1-dicarboxylic Acid Anions

The reactions of Cr(NO3)3 ⋅ 9H2O with barium and calcium salts of cyclobutane-1,1-dicarboxylic acid (H2Cbdc) in a ratio of 1 : 3 in an aqueous solution are studied. The reaction products isolated in the crystalline state are shown to be compounds formed by the binuclear tetraanionic units Cr2(OH)2(Cbdc)4] 4−, and the nature of the alkaline-earth metal ion introduced into the synthesis affects the dimensionality of the formed polymeric structure. The 2D polymeric compound Ba2Cr2(OH)2(Cbdc)4(H2O)5] ⋅ 3H2O}