Spectroscopic and spectromagnetic study of adenosine chloroderivatives of bivalent Co, Ni, Cu, Zn, Cd. Comparison with the corresponding adenine chloroderivatives

[M″LnCl2] (n = 1,2) (M″= Co, Ni, Cu, Zn, Cd, Hg) (L = adenine, adenosine) compounds were synthesized and the magnetic, electronic and vibrational properties of adenosine derivatives were considered in comparison with those of adenine complexes. It was found that the ligand field symmetry is distorted tetrahedral in cobalt, zinc compounds and in CuLCl2; distorted octahedral in Ni, Cd, Hg compounds and in CuL2Cl2. Sugar moiety of adenosine is not implied in the coordination to the metal center. Distortions from regular symmetries were recognized by ESR measurements and confirmed by vibrational analysis; it resulted an higher distorting power of adenosine than of adenine. Both monodentate and bridging N(3)-N(9) or N(1)-N(7) coordination were discussed. The MN bond strength resulted higher for bridged coordination. ESR sensitive change of spin state were observed in CoL2Cl2 compounds. Vibrational measurements on purine absorption modes suggest that the ligand is not strongly perturbed by the metal coordination. © 1981.