Implications of Guanidine Substitution on Copper Complexes as Entatic-State Models

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• 作者：Alexander Hoffmann ; Julia Stanek ; Benjamin Dicke ; Laurens Peters ; Benjamin Grimm-Lebsanft ; Alina Wetzel ; Anton Jesser ; Matthias Bauer ; Manuel Gnida ; Wolfram Meyer-Klaucke ; Michael Rü ; bhausen and Sonja Herres-Pawlis
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：2016
• 期：29
• 页码：4731-4743
• 全文大小：3071K
• ISSN：1099-0682c

文摘

The guanidine–quinoline ligand dimethylethyleneguanidinoquinoline (DMEGqu) is able to stabilise bis(chelate) copper complexes in an intermediate geometry between tetrahedral and square-planar environments. The structures of the obtained complexes model the entatic state and have been investigated in solid state by single-crystal X-ray diffraction and in the solid state and in solution by X-ray absorption spectroscopy. The dimethylethyleneguanidine (DMEG) unit of the DMEGqu ligand displays a smaller steric encumbrance than the tetramethylguanidine (TMG) counterpart; this allows slightly larger structural changes upon oxidation than those for the TMG counterparts. Moreover, triflate coordination was possible for the Cu^II DMEG complexes. DFT analyses revealed that good structural and optical descriptions are possible through the use of the hybrid functionals B3LYP and TPSSh in combination with the triple-zeta basis set def2-TZVP and the inclusion of empirical dispersion with Becke–Johnson damping and a suitable solvent model. The orbital analysis gives insights into the electronic structure of the complexes and their charge-transfer behaviour.