The reaction of 2,2′-bipyridine-5,5′-dicarboxylic acid (HO2CC12H6N2CO2H, H2bpydicarb) with the appropriate metal salt in water provided the mononuclear complexes [M(II)(bpydicarb)(H2O)4]·2H2O where M(II) = Co and Ni. The isomorphous materials exhibit neutral six-coordinate metal–ligand complexes with MN2O4 geometry. Charge balance is achieved through deprotonation of the carboxylate groups. The Co compound crystallizes in the monoclinic space group C2/c with a = 12.696(4) Å, b = 9.195(4) Å, c = 13.207(5) Å, β = 93.78(1)°; the isomorphous Ni compound exhibits cell parameters a = 12.477(4) Å, b = 9.818(3) Å, c = 12.658(4) Å, β = 92.099(6)°. The six coordinate structure of [Co(II)(bpydicarb)(H2O)4] achieves charge balance through deprotonation of the carboxylate residues of the bipyridine-based ligand.

中文翻译：

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2,2'-联吡啶-5,5'-二羧酸配合物的晶体和分子结构：[M(II)(O2CC10H6N2CO2)(H2O)4] (M = Co, Ni)

2,2'-联吡啶-5,5'-二羧酸（HO2CC12H6N2CO2H，H2bpydicarb）与合适的金属盐在水中的反应提供了单核配合物[M(II)(bpydicarb)(H2O)4]·2H2O，其中M (II) = Co 和 Ni。同晶材料表现出具有 MN2O4 几何结构的中性六配位金属配体配合物。电荷平衡是通过羧酸盐基团的去质子化实现的。Co 化合物在单斜空间群 C2/c 中结晶，a = 12.696(4) Å, b = 9.195(4) Å, c = 13.207(5) Å, β = 93.78(1)°；同晶 Ni 化​​合物的晶胞参数 a = 12.477(4) Å, b = 9.818(3) Å, c = 12.658(4) Å, β = 92.099(6)°。[Co(II)(bpydicarb)(H2O)4] 的六坐标结构通过联吡啶基配体的羧酸盐残基的去质子化实现电荷平衡。