Zinc Organic Compounds Research Articles

Covalent and Ionic: Bonding Characteristics of HZnCH and ZnCH2and Their Interconversions

AbstractThe structures of zinc carbene ZnCH2and zinc carbyne HZnCH, and the conversion transition states between them are optimized at B3LYP/aug‐cc‐pVTZ, MP2/aug‐cc‐pVTZ, and CCSD/aug‐cc‐pVTZ levels of theory. The thermodynamic energies with CCSD(T) method are further extrapolated to basis set limit through a series of basis sets of aug‐cc‐pVXZ (X=D, T, Q, 5). The Zn−C bonding characteristics are interpreted by molecular plots, Laplacian of density plots, the integrated delocalization indices, net atomic charges, and derived atomic hardness. On the one hand, the studies demonstrated the efficiency of DFT method in structure optimizations and the accuracy of CBS method in obtaining thermodynamic energies; On the other hand, the density analysis of CCSD/aug‐cc‐pVDZ density demonstrates that both the sharing interaction and ionic interaction are important in ZnCH2ad HZnCH. The3B1state of ZnCH2is the global minimum and formed in visible light, but its small bond dissociation energy (47.0 kcal/mol) cannot keep the complex intact under UV light (79.4–102.1 kcal/mol). However, the3Σ−state of HZnCH can survive the UV light due to the greater Zn−C dissociation energy (100.7 kcal/mol). The delocalization indices of Zn…C in both3B1of ZnCH2(0.777) and the3Σ−state of HZnCH (0.785) are close to the delocalization index of the single C−C bond of ethane (0.841), i. e. the nomenclature of Zinc carbene and Zinc carbyne is incorrect. The stronger Zn−C bond in the3Σ−state of HZnCH than in the3B1state of ZnCH2can be attributed to the larger charge separation in the former. It was found that the Zn−C bonds in related Zinc organic compounds were also single bonds no matter whether the organic groups are CR, CR2, or CR3. The ionic interactions were discussed in terms of the atomic hardness that were in turn related to ionization energy and electron affinity. The unique combination of covalent and ionic characteristics in the Zn−C bonds of organic Zinc compounds could be the origin of many interesting applications of organic Zinc reagents.

Cyclodimerization reactions of the β-ferrocenylvinyl(methyl)ketones in the presence of zinc-organic compounds

Trans-ferrocenyl-3-buten-2-one 1 undergoes cyclic dimerization with formation of 4-acetyl-3,5-diferrocenylcyclohexanone 5 and 5,8-diferrocenyl-1-hydroxybicyclo-[2.2.2.]octan-3-one 6 in the presence of cyclohexenes and 2-PyZnBr or Me2Zn. No adducts of the Diels–Alder reaction of compound 1 in its enolic form with cyclohexenes were observed. Under similar conditions, in the absence of cyclohexenes trans-ferrocenyl-3-buten-2-one 1 affords cyclodimer 5 and cyclotrimer – 6-acetyl-4,5,7-triferrocenyl-1,9-dehydro-2-decalone 7. 3-(Ferrocenylmethylidene)pentane-2,4-dione 2a and ethyl (E)-2-acetyl-3-ferrocenylacrylate 2b cyclodimerized analogously with formation of 3,5-diferrocenyl-1-hydroxy-2,4,4-triacetylcyclohexene 8a and diethyl 4-acetyl-3,5-diferrocenyl-1-hydroxycyclohexene-2,4-dicarboxylate 8b, respectively. The structures of the obtained compounds were established based on data from IR, 1H and 13C NMR spectroscopy, mass spectrometry and X-ray diffraction analysis. The mechanistic aspects of these reactions are discussed.

Zinc organic compounds of some oximes coordinated with nickel(II), palladium(II) and copper(II) ions

AbstractCoordinated oximes with nickel(II), palladium(II) and copper(II) ions proved capable of giving substitution reactions with a series of zinc organic compounds. Studies have revealed that, in the cases of dimethylglyoxime and salicylaldoxime, the reaction products result from substitution of the OH···O hydrogen bridges existing in such compounds by OZnO bridges. All compounds reported in this paper were separated as colored powders and characterized by elemental analyses, IR spectroscopy, X‐ray diffraction and magnetic measurements. The new zinc organic compounds form amine adducts. Among the amine adducts, only those with pyridine were isolated and characterized. Copyright © 2001 John Wiley & Sons, Ltd.

ChemInform Abstract: Reactions of Polyhalogenofunctionalized Compounds with Metals and Electrophilic Reagents. Part 6. Reaction of 2,2,2-Trichloroethylidene Derivatives of β-Dicarbonyl Compounds with Zinc and α-Chlorosulfides.

The trichloroethylidenedicarbonyl compounds (I) react with Zn to form the corresponding zincorganic compounds, which can be isolated.

ChemInform Abstract: Novel Syntheses with Participation of Zinc‐organic Compounds. Synthesis of β‐Acyloxy Ketones.

AbstractThe bromocarbonyl compounds (I) are ttransformed to the corresponding zinc‐organic derivatives (II) in the presence of HgClgas catalyst.