Seven-coordination versus six-coordination in divalent first-row transition-metal complexes derived from 1,10-diaza-15-crown-5
Seven-coordination versus six-coordination in divalent first-row transition-metal complexes derived from 1,10-diaza-15-crown-5
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DOI：
10.1021/ic7008946
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发表时间：
2007-10-01
影响因子：
4.6
通讯作者：
Rodriguez-Blas, Teresa
中科院分区：
文献类型：
--
作者：
Vaiana, Lea;Regueiro-Figueroa, Martin;Rodriguez-Blas, Teresa
本文报道了七齿受体N，N '-双（苯并咪唑-2-基甲基）-1，10-二氮杂-15-冠-5（L-2）与Mn-Ⅱ、Co-Ⅱ、Ni-Ⅱ、Cu-Ⅱ和Zr-Ⅱ的配合物。Zn-II和Ni-II配合物的X-射线晶体结构表明，虽然Zn-II离子是七配位的（distolrled）五角双锥配位环境中，N-II离子只有六配位的扭曲八面体配位环境。在密度泛函理论（DFT; B3 LYP）水平上对[M（L-2）]（2+）体系（M = Mn，Go，Ni，Cu或Zn）进行了理论计算，获得了这些配合物的结构和电子性质的信息，并合理化了它们对五角双锥或八面体配位的偏好。我们已经发现，对于Mn-II，Co-II，Cu-II和Zn-II络合物，几何优化系统地导致金属离子周围的五角-双锥配位环境。而对于Ni-II配合物，得到了两种最低能量构象，金属离子为八面体（o-[Ni（L-2）]（2+））或五角双锥（pb-[Ni（L-2）]（2+））配位。在镍-II络合物中的八面体几何形状的稳定化可以被认为是在五角双锥几何形状中操作的Jahn-Teller效应的结果，其在极端情况下导致八面体配位。在二甲基亚砜（DMSO）和乙腈/DMSO（9：1）溶液中进行的分光光度测试表明，L-2：Co-II配合物的稳定性顺序为Ni-II> Zn-II>> Mn-II。配合物的几何形状和稳定性的变化可以合理化的前线分子轨道的不同职业沿着第一行过渡金属系列。最后，在B3 LYP水平上优化了[Cu（L-2）]（2+）配合物的几何构型，采用含时密度泛函方法研究了配合物的吸收光谱，证实了该配合物在溶液中的五角-双锥配位.
The complexes of the heptadentate receptor N,N'-bis(benzimidazol-2-ylmethyl)-1,10-diaza-15-crown-5 (L-2) with Mn-II, Co-II, Ni-II, Cu-II, and Zr-II are reported. The X-ray crystal structures of the Zn-II and Ni-II complexes show that whereas the Zn-II ion is seven -coordinated in a (distolrled) pentagonal-bipyramidal coordination environment, the N-II ion is only six-coordinated in a distorted octahedral coordination environment. Theoretical calculations on the [M(L-2)](2+) systems (M = Mn, Go, Ni, Cu, or Zn) performed at the density functional theory (DFT; B3LYP) level have been used to obtain information about the structure and electronic properties of these complexes, as well as to rationalize their preferences for a pentagonal-bipyramidal or an octahedral coordination. We have found that for the Mn-II, Co-II, Cu-II, and Zn-II complexes, geometry optimizations lead systematically to pentagonal -bipyramidal coordination environments around the metal ions. However, for the Ni-II complex, two minimum-energy conformations were obtained, with the metal ion teing in octahedral (o-[Ni(L-2)](2+)) or pentagonal-bipyramidal (pb-[Ni(L-2)](2+)) coordination. The stabilization of the octahedral geometry in the Ni-II complex can be considered as the result of the Jahn-Teller effect operating in pentagonal-bipyramidal geometry, which in an extreme case leads to an octahedral coordination. Spectrophotometric t trations carried out in dimethyl sulfoxicle (DMSO) and CH3CN/DMSO (9:1) solutions indicate the following stability sequence for the complexes of L-2: Co-II approximate to Ni-II > Zn-II >> Mn-II. The variations in the geometry and stability of the complexes may be rationalized in terms of the different occupations of the frontier molecular orbitals along the first-row transition-metal series. Finally, a time-dependent DFT approach was used to investigate the absorption spectrum of the [Cu(L-2)](2+) Complex based on the optimized geometries at the B3LYP level, also confirming a pentagonal-bipyramidal coordination in solution for this compound.