Structural characterization of cis-2,6-(E,E)-bis(ferrocenylidene)-N-methyl-4-piperidone and DFT evaluation of alternative polymorphic modifications via ferrocene rotation

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• 作者：Volodymyr V. Nesterov^a ; Vladimir N. Nesterov^b ; ^{Vladimir.Nesterov@unt.edu} ; Michael G. Richmond^b ; ^{cobalt@unt.edu}
• 关键词：Bis(chalcones) ; X-ray crystallography ; DFT ; Rotational isomerism ; Polymorphism ; Ferrocene
• 刊名：Polyhedron
• 出版年：2012
• 期刊代码：87_02775387
• 类别：ch
• 出版时间：16 March, 2012
• 卷：35
• 期：1
• 页码：124-129
• 文件大小：770 K

摘要

The molecular structure of cis-2,6-(E,E)-bis(ferrocenylidene)-N-methyl-4-piperidone (1) has been determined by X-ray crystallography. Compound 1 crystallizes in the monoclinic chiral space group P2(1), a = 6.0055(17) 脜, b = 12.802(4) 脜, c = 14.465(4) 脜, 尾 = 95.438(4)掳, V = 1107.1(5) 脜³, Z = 2, and D_calc = 1.516 Mg/m³; R = 0.0335, Rw = 0.0682 for 4230 reflections with I > 2蟽(I). The substituents at the vinyl group of each chalcone moiety exhibit a trans (entgegen) disposition, and the two ferrocene moieties adopt a syn orientation and are located on the side of the piperidone ring opposite of the nitrogen lone electron pair. Molecules of 1 pack in chains along the a axis and exhibit weak intermolecular C-H鈰疧 hydrogen bonds involving the ferrocene and carbonyl moieties of adjacent molecules. The energy difference between the ferrocene rotational isomers in 1 has been evaluated by DFT, and the lowest energy structure is represented by the solid-state structure. The barriers for the rotational isomerization of the ferrocene groups have been evaluated and are discussed in the context of polymorphic modifications available to 1.