Zh. Zhang et al., SYNTHESES AND PROPERTIES OF THE COMPLEXES OF COPPER(II) WITH 1,4,7,10-TETRAAZACYCLOTRIDECANE-11,13-DIONE APPENDED WITH 2-METHYLTHIOPHENE PENDANTS, Synthesis and reactivity in inorganic and metal-organic chemistry, 28(3), 1998, pp. 487-496
Two new macrocyclic 1,4,7,10-tetraazacyclotridecane-11,13-diones (diox
o[13]aneN(4)) bearing 2-methylthiophene as additional pendants, H2L1 a
nd H2L2, have been synthesized and characterized. The solution behavio
ur of the copper(II) complexes has been studied by UV-Vis, ESR and cyc
lic voltammetric techniques. A remarkable red-shift was observed for t
he absorption band maxima of the electronic spectra of CuL1 and CuL2 c
ompared to that of the corresponding unsubstituted macrocycle copper c
omplex CuL (H2L = macrocyclic ligand, 1,4,7,10-tetraazacyclotridecane-
11,13-dione, without pendant groups). The ESR spectra have been studie
d at 298 K and 112 K, and reflect weaker in-plane bonding in CuL1 and
CuL2 compared to CuL. The E-1/2 of the copper complexes increases with
the increase of the number of additional pendants, and the reasons fo
r this are discussed.