Redox-Active Polymers Based on Nonbridged Metal-Metal Bonds.ELectrochemical Formation of[Os(bpy)(CO)(L)]_n(bpy=2_12'-bipyridine;L=CO,MeCN)and of Their Reduced Forms:A SpectroELectrochemical Study

摘要

IR,UV-vis,and EPR speclroELectrochemistry at variable temperatures and in different solvents were applied to investigate in situ the formation of ELectroactive molecular chains with a nonbridged Os-Os backbone,in particular,the polymer[Osdeg(bpy)(CO)_2]_n(bpy=2_12'-bipyridine),from a mononuclear Os(ll)carbonyl precursor,[Os~II(bpy)(CO)_2-CL_2].The one-ELectron-reduced form,[Os~(II)(bpy~(centre dot)-)(CO)_2CL_2]~-,has been characterized spectroscopically at low temperatures.This radical anion is the key intermediate in the ELectrochemical propagation process responsible for the metal-metal bond formation.Unambiguous spectroscopic evidence has been gained also for the formation of[{Osdeg(bpy~(centre dot)-)(CO)_2}~-]_n,the ELectron-rich ELectrocatalyst of C0_2 reduction.The polymer species are fairly wELl soluble in butyronitrile,which is important for their potential utilization in nanoscience,for example,as conducting molecular wires.We have also shown that compL~(Et)e solubility is accomplished for the monocarbonyl-acetonitrile derivative of the polymer,[Os~0(bpy)(CO)(MeCN)_2CI]_n.