Knowledge Bank

The resonance Raman spectra of a series of Cu(II) complexes with macrocyclic and open chain polythiaether ligands are reported. The ligands, L, (L = 1,4,7,10 - tetrathiacyclododecane; 1,4,7,10 - tetraehiacyclo-tridecane; 1,4,8,11 - tetrathiacyclotetradecane; 1,4,8,12 - tetrathia-cyc1opentadecane; 1,5,9,13 - tetrachiacyclohexadecane; 1,4,7,10,13 - pentathiacyelopentadecane; 1,4,7,10,14,17 - hexathiacycloeicosane 1,5,9 - trithiacyclododecane and 3,6,10,13 - tetrachiapentadecane) vary in their number of sulfur donors and macrocyclic ring size, including one non-macrocyclic structure. In each case, the symmetric Cu-S stretching vibration exhibits strong resonance with a S($\sigma )\to$ Cu(II) charge transfer transition at approximately 400 nm, and weak resonance with a S($\pi )\to$ Cu(II) charge transfer transition at approximately 600 nm. In addition, Other Cu-S and C-S modes of the complexes exhibit resonance enhancement. The Raman excitation profiles are discussed with regard to their fit to theory. The observed Raman frequencies are discussed in relation to spectroscopic, thermodynamic, kinetic and structural manifestations of the macrocyclic effect.