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Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime–Zn System
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2017-11-09 00:00:00 , DOI: 10.1021/acs.inorgchem.7b01891
Adedamola A. Opalade 1 , Anirban Karmakar 2 , G. M. D. M. Rúbio 2 , Armando J. L. Pombeiro 2 , Nikolay Gerasimchuk 1
Affiliation  

Reaction of 2-hydroxyimino-4,4-dimethyl-3-oxo-pentanenitrile (common abbreviation HPiCO, pivaloyl-cyanoxime) with zinc sulfate in an aqueous solution results in the formation of the two new complexes: [Zn(PiCO){H(PiCO)2}(H2O)] (I) and tetranuclear Zn complex [Zn43–OH)2(PiCO)6 (H2O)4] (II). Both complexes were characterized by elemental analysis, IR– and UV–visible spectra, DSC/TGA studies, and X-ray analysis. In complex II, the PiCO cyanoxime anion adopts three bidentate binding modes: O-monodentate, chelating (κ2), and bridging (η2) coordinations. Also, the ligand represents the mixture of two diasteromers (cis–anti and cis–syn) that form five- and six-membered chelate rings with Zn atoms and cocrystallize in one unit cell at population of 0.57–0.43. There are two crystallographically different Zn-centers in the ASU, and two μ3-bridging hydroxo-groups arrange via inversion center the formation of an elegant tetranuclear complex. Each Zn atom has a molecule of coordinated water and is in the distorted octahedral environment. Because of the structural flexibility and multidentate propensity of the pivaloyl-cyanoxime, complex II may act as a structural model of naturally occurring Zn-containing enzymes. Indeed, compound I exhibits an efficient catalytic performance for transesterification reaction of various esters in ethanol under mild reaction conditions. Therefore, obtained results allow assignment of observed activity as green catalysis.

中文翻译:

含氰基肟的锌配合物:新戊酰氰基肟-锌体系的结构,光谱和催化研究

2-羟基亚氨基-4,4-二甲基-3-氧代戊腈(通用缩写HPiCO,新戊酰氰肟)与硫酸锌在水溶液中的反应导致形成两种新的配合物:[Zn(PiCO){H (微微)2 }(H 2 O)]()和四核Zn络合物[锌4(μ 3 -OH)2(微微)6(H 2 O)4 ](II)。通过元素分析,红外和紫外可见光谱,DSC / TGA研究和X射线分析对这两种配合物进行了表征。在复杂的II,微微- cyanoxime阴离子采用三二种齿配位模式:O型单齿,螯合剂(κ 2),和桥接(η 2)配位。同样,配体代表两种非对映异构体的混合物(顺反和顺顺),它们与锌原子形成五元和六元螯合环,并在一个单位细胞中以0.57-0.43的比例共结晶。有两种不同的晶体的Zn-中心在ASU和两个μ 3 -bridging羟-基团经由反转中心安排优雅的四核配合物的形成。每个Zn原子都有一个配位水分子,并且处于扭曲的八面体环境中。由于新戊酰基-氰肟的结构灵活性和多齿倾向,复合物II可以作为天然存在的含锌酶的结构模型。确实,化合物I在温和的反应条件下,对乙醇中的各种酯进行酯交换反应具有高效的催化性能。因此,获得的结果允许将观察到的活性指定为绿色催化。
更新日期:2017-11-09
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