EPR spectral studies on 1–8 have been performed at room temperature
in CH2Cl2 solution.
Ensuing parameters are given in
Table S6 and the spectra depicted in Fig. 5 and S11–S16.
The complexes
exhibited g|| and g values in the range 2.0449–2.2163 and
2.0193–2.0434, respectively which are comparable to other copper(
II) complexes exhibiting square planar or square pyramidal
geometry.
Observed g values for the complexes under
study are less than 2.3 and in agreement with covalent character of the metal ligand bond
As expected the X-band EPR
displayed well resolved characteristic four line axial spectra with
a nuclear hyperfine spin (I = 3/2).
The g|| > g > 2.003 observed for
complexes is typical for d9 copper(II) and a ground state doublet
indicated that unpaired electron resides in a dx2y2 orbital
Notably, 2, 4 and 6 having hfacac unit exhibit an additional
hyperfine F-coupling.
The complexes 1–8 exhibited paramagnetism
corresponding to a single electron at room temperature.