Abstract This work deals with the synthesis and spectroscopic characterization of novel complexes involving the coordination of croconate (C5O5)2- and 5,5′-dimethyl-2,2′-bipyridyl (DmBpy) ligands to the transition metal ions Co2+ and Cu2+. Two complexes involving the croconate species with the DmBpy ligand were obtained. The complex [Cu(C5O5)(DmBpy)(H2O)].H2O (1) crystallizes in a monoclinic system, belonging to the P21/c space group and Z equal to four, whereas[Co(C5O5)(DmBpy)(H2O)2] (2) crystallizes in a triclinic system and belonging to the P-1 space group and Z equal to four. The Cu(II) complex presents a slightly distorted square base pyramid geometry, presenting a water molecule at the vertical position, whereas Co(II) compound shows an octahedral geometry with two water molecules at the vertices. In both compounds croconate ions act as a building block, and the nitrogenous ligand is the spacer agent, giving rise to the 3D structure. The vibrational analysis (Raman and infrared) supports the crystallographic data, and several band markers are identified in order to understand the supramolecular interactions, such as the stretching modes νCC/νCN at 1600 and 1498 cm−1, respectively, shifted by the coordination to higher wavenumbers in both compounds (1604 and 1507 cm−1, and 1604 and 1508 cm−1, for (1) and (2) respectively), thus strongly corroborating the coordination of the ligand to the metal site through the nitrogen atoms present in the pyridine moiety. On the other hand, the band at 1718 cm−1, assigned to the (CO ) stretching mode from croconate ion, can be used as the main band marker, due to the observed shift caused by the coordination to the metal center.

中文翻译：

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基于croconate离子和5,5'-二甲基-2,2'-二吡啶基配体的新型Cu2+和Co2+配合物的振动和结构研究

摘要 这项工作涉及新配合物的合成和光谱表征，这些配合物涉及鳄鱼酸 (C5O5)2- 和 5,5'-二甲基-2,2'-联吡啶 (DmBpy) 配体与过渡金属离子 Co2+ 和 Cu2+ 的配位。获得了两种涉及鳄鱼酸物质与 DmBpy 配体的复合物。复合物 [Cu(C5O5)(DmBpy)(H2O)].H2O (1) 在单斜晶系中结晶，属于 P21/c 空间群，Z 等于 4，而 [Co(C5O5)(DmBpy)(H2O) )2] (2) 在三斜晶系中结晶，属于 P-1 空间群，Z 等于 4。Cu(II) 复合物呈现略微扭曲的方形基础金字塔几何形状，在垂直位置呈现水分子，而 Co(II) 化合物呈现八面体几何形状，在顶点处具有两个水分子。在这两种化合物中，croconate 离子充当构建块，含氮配体是间隔剂，产生 3D 结构。振动分析（拉曼和红外）支持晶体学数据，并确定了几个带标记以了解超分子相互作用，例如分别在 1600 和 1498 cm-1 处的拉伸模式 νCC/νCN，通过协调移动到两种化合物中的更高波数（1604 和 1507 cm-1，以及 1604 和 1508 cm-1，分别为（1）和（2）），从而有力地证实了配体通过存在于其中的氮原子与金属位点的配位吡啶部分。另一方面，在 1718 cm−1 处的谱带，分配给来自鳄鱼酸离子的 (CO ) 拉伸模式，可用作主要谱带标记，