Orbital characteristics, lowest complexes

CMR (10) and ultraviolet (UV). The interaction in a CT complex is considered to involve an electron transfer from the highest occupied molecular orbital (HOMO) of an electron donating comonomer to the lowest occupied molecular orbital (LUMO) of an electron accepting comonomer (11). This electron transfer results in a new absorption in UV, a characteristic of the CT complex. 

Once the gross orbital types of the lowest excited states of complexes are determined, subtle alterations in properties can be effected by varying ligand substituents, by modifying the environment of the active species, or by subjecting the materials to external perturbations. This fine tuning of spectroscopic characteristics has produced a number of unusual electronic properties with potential use for exploitation in both a fundamental and a practical way. We direct attention particularly to charge-transfer excited states. 

The Ru(II)-Rh(III) cyanide-bridged complexes show absorptions that are characteristic for ruthenium and rhodium polyazine complexes. The electronic absorption spectra of a series of cyanide-bridged Ru(H)-Rh(ni) complexes recorded in DMSO-H2O solutions correlate well with the electrochemical properties. Coordination of a second Rh(III) shifts the lowest energy transition, which is Ru bpy MLCT in nature, to higher energy in [(bpy)2Ru (CN)Rh(NH3)5 2] relative to [(bpy)2(CN)Ru(CN)Rh(NH3)5] . This positive shift is consistent with the stabilization of the Ru(djt) orbitals of [(bpy)2Ru (CN)Rh(NH3)5 2] and correlates well with the electrochemistry where the Ru° oxidation moves to more positive potential with Rhflll) addition. The of... 

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