50988-94-8Relevant articles and documents
Substituent Effects of β-Diketiminate Ligands on the Structure and Physicochemical Properties of Copper(II) Complexes
Shimokawa, Chizu,Yokota, Seiji,Tachi, Yoshimitsu,Nishiwaki, Nagatoshi,Ariga, Masahiro,Itoh, Shinobu
, p. 8395 - 8405 (2008/10/09)
Substituent effects of β-diketiminate ligands on the structure and physicochemical properties of the copper(II) complexes have been systematically investigated by using 3-iminopropenylamine derivatives R1L R3H, R3-N=CH-C(R1)=CH-NH-R3, where R1 is Me, H, CN, or NO2, and R3 is Ph, Mes (mesityl), Dep (2,6-diethylphenyl), Dipp (2,6-diisopropylphenyl), or Dtbp (3,5-di-tert-butylphenyl). When the ligands with R3 = Ph or Dtbp were treated with CuII(OAc)2, bis(β-diketiminate) copper(II) complexes exhibiting distorted tetrahedral geometries were obtained, the crystal structures of which were nearly the same as each other regardless of the α-substituent (R1); dihedral angles between the two β-diketiminate coordination planes are 62.5 ± 1.2°, and the Cu-N bond lengths are 1.959 ± 0.008 A. The distorted tetrahedral structures are maintained in solution, but the spectroscopic features, especially gII values of the ESR spectra and the d-d bands of the absorption spectra, as well as the electrochemical behaviors of the complexes, are significantly affected by the electronic nature of R1. The ligands with R3 = Mes and Dep, on the other hand, gave di(μ-hydroxo)dicopper(II) complexes, and their crystal structures as well as spectroscopic and electrochemical features have also been explored. Furthermore, the ligand with the more sterically encumbered aromatic substituent (Dipp) provided a mononuclear four-coordinate square planar copper(II) complex supported by one β-diketiminate ligand and one didentate acetate ion. Thus, the β-diketiminate ligands with a variety of substituents (R1 and R3) have been explored to provide coordinatively unsaturated (four-coordinate) mononuclear and dinuclear copper(II) complexes with significantly different coordination geometry and properties.