Coordination-driven self-assembly of thiocyanate complexes of Co(II), Ni(II) and Cu(II) with picolinamide: a structural and DFT study
Coordination-driven self-assembly of thiocyanate complexes of Co(II), Ni(II) and Cu(II) with picolinamide: a structural and DFT study
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DOI：
10.1039/c1ce05332a
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发表时间：
2011-01-01
期刊：
影响因子：
3.1
通讯作者：
Popovic, Zora
中科院分区：
文献类型：
--
作者：
Dakovic, Marijana;Vila-Vicosa, Diogo;Popovic, Zora
合成并表征了新的杂感配合物[M(NCS)(2)(Pia)(2)]M Co(Ii)(1)，Ni(Ii)(2)和[Cu(SCN)(2)(Pia)(2)](3)，pia=吡啶-2-甲酰胺。它们的单晶X-射线衍射结构显示为八面体单元，两个硫氰酸盐配体占据顺式位置，并通过氮原子键合在Co(II)和Ni(II)中。在铜(II)络合物中，它们是反式和S结合的。Co(II)和Ni(II)的晶体结构为具有NH中心的S氢键的二维结构，形成四聚单元，并与锌(II)的配合物[Zn(Ncs)_2(Pia)_2]同构，而对于铜(II)的晶体结构为具有NH中心N的二维结构。用密度泛函理论计算了新的配合物和类似的[Zn(Ncs)(2)(Pia)(2)]的晶型，包括第二个含有二聚体基序的晶型。计算得到的硫氰酸盐配体的振动模式与实验结果相吻合，反映了配体的配位模式。两种锌(II)晶型的比较表明，四聚体中的NH中心点S键比二聚体中的NH中心点氧键更强(-7.50kcal mol(-1)/金属)，表明四聚体单元的形成倾向于四聚体单元的形成。计算结果表明，在Ni(II)和Zn(II)中，Cu(II)晶体中的NH中心点N氢键比NH中心点S的强(-9.15kcal mol-1)。
The new heteroleptic complexes, [M(NCS)(2)(pia)(2)] M Co(II) (1), Ni(II) (2), and [Cu(SCN)(2)(pia)(2)] (3), pia = pyridine-2-carboxamide, were synthesized and characterized. Their single crystal X-ray diffraction structures showed octahedral units, with the two thiocyanate ligands occupying cis-positions and binding through the nitrogen atom in Co(II) and Ni(II). In the Cu(II) complex, they were trans and S-bound. The crystal structures display a 2-d structure with NH center dot center dot center dot S hydrogen bonds for the Co(II) and Ni(II), forming tetrameric units, and are isomorphous with the Zn(II) complex, [Zn(NCS) 2(pia) 2], and a 2-d structure with NH center dot center dot center dot N for the Cu(II). DFT calculations were performed on the new complexes and the analogous polymorphs of [Zn(NCS)(2)(pia)(2)], including a second one containing dimeric motifs. The calculated vibrational modes of the thiocyanate ligands corroborate the experimental ones and reflect the coordination mode of the ligand. A comparison between the two Zn(II) polymorphs showed that the NH center dot center dot center dot S bond in the tetramer is stronger (-7.50 kcal mol(-1) per metal) than the NH center dot center dot center dot O bond in the dimer (-4.01 kcal mol(-1) per metal), indicating a preference for the formation of tetrameric units. The NH center dot center dot center dot N hydrogen bonds calculated in the Cu(II) crystal are stronger (-9.15 kcal mol(-1) per metal) than the NH center dot center dot center dot S ones in Ni(II) and Zn(II).