Synthesis and structure determination of two new dinuclear end-to-end doubly bridged azido- and thiocyanato-copper(II) complexes derived from diethyldiethylenetriamine

Herein, we report the synthesis and characterization of two new dinuclear bridged azido and bridged thiocyanato complexes: [Cu2(Et2dien)2(μ1,3-N3)2](ClO4)2 (1) and [Cu2(Et2dien)2(μN,S-NCS)2]-(ClO4)2 (2) where Et2dien = N ,N -diethyldiethylenetriamine. In both complexes, the two copper centers are linked by two azide or two thiocyanate groups in end-to-end bonding fashion. The copper ions are penta-coordinated by three N-atoms of the Et2dien ligand, one N atom from the bridging azido in 1 or from the thiocyanato group in 2. The fifth coordination site is occupied by N or S atom from the second bridging azide or thiocyanate ligand, respectively. The coordination geometry around the Cu(II) ions in the two complexes may be described as close to square pyramidal (SP) stereochemistry with severe distortion to trigonal bipyramidal (TBP) stereochemistry. The intradimer Cu⋯Cu distances are 5.264(1) and 5.571(1) Å for the azido and thiocyanato complex, respectively. The IR stretching frequencies of the azido, View the MathML sourceν(N3-) and the thiocyanato, ν(NCS−) groups in the 2030–2120 cm−1 region are discussed in relation to other related species. The visible spectra of the complexes studied in different solvents reveal the assigned predominant SP stereochemistry in solution with the presence of a pronounced amount of TBP geometry in the thiocyanato complex. Moreover, the complexes undergo solvolysis through bond rupture and displacement of one of the bridged azido or thiocyanato ligands.