Substituent Effects on Structural, Electronic, and Redox Properties of Bis( N ‐alkyl‐2‐oxy‐1‐naphthaldiminato)copper(II) Complexes Revisited – Inequivalence in Solid‐ and Solution‐State Structures by Electronic Spectroscopy and X‐ray Diffraction Explained by DFT

Autor: Juan Costamagna, Francesco Caruso, M. Villagrán, José H. Zagal, Miriam Rossi
Rok vydání: 2010
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2010:1373-1380
ISSN: 1099-0682
1434-1948
DOI: 10.1002/ejic.200900298
Popis: Bis(N-alkyl-2-oxy-1-naphthaldiminato)copper(II) complexes in the solid state and in N,N'-dimethylformamide (DMF) solutions were studied by electronic spectroscopy, X-ray diffraction, DFT calculations, and cyclic voltammetry. The established correlation between the bulkiness of the imine nitrogen substituent, deformation of the copper coordination sphere, and the Cu II /Cu I couple potential in DMF solutions has been re-evaluated, and its inconsistencies explained by using results from DFT calculations and spectroscopic data. According to these DFT calculations, the coordination sphere of the N-ethyl derivative has a flat-tetrahedral geometry. The N-Cu-N' and O-Cu-O' angles and the dihedral angle between the planes N-Cu-O and N'-Cu-O' in the solid state found by X-ray diffraction in this study are affected by crystal packing forces. UV/Vis spectra of the N-ethyl, N-iPr, and N-tBu derivatives suggest that the first two compounds have fluxional behavior characterized by a centrosymmetric transition state, whereas the tBu group in the N-tBu derivative prevents such dynamic action. In the crystal, this N-tBu complex changes upon DFT geometry optimization to a more tetrahedral configuration. Therefore, in contrast to X-ray crystal structures reported in the literature of complexes with primary N-alkyl substituents that show a planar Cu coordination sphere (i.e. N-Cu-N' and O-Cu-O' bond angles of 180°), these complexes are not planar in solution or as isolated molecules.
Databáze: OpenAIRE
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