Axial bonds in copper (II) compounds

摘要

Structures and spectroscopic properties of copper (II) compound of two cyclam derivatives L~1 and L~2 re reported. L~1 has four 4-cyanobenzyl N-substituents and L~2 has a fused barbiturate ring at one of the two propylene bridges. The copper (II) complexes of L~1 ([Cu((L~1)(ncch_3)]~(2+) and [Cu((L~1)(OH_2)]~(2+)) have trans -I configuration and are five-coordinate with extremely short axial bonds. The reaction of [Cu((L~2)(OH_2)_2]~(2+) (purple, six-coordinate, trans-III configuration) with urea and NCS~1 leads to a blue five-coordinate, and with urea alone to a red four -coordiante species. The CuN_4 chromophores of three copper (II) compounds of L~2 are close to identical, and the color changes are analyzed to be due to the differences in axial interactions