Dinuclear complexes, absorption

Table 3 Principal low-energy absorption maxima of dinuclear complexes [ Mo(Tp )(0)Cl 2 (p-L) + in their...

The observation of a strong infrared absorption at below 2,000 cm for the dinuclear complex of (185) incorporating manganese thiocyanate was taken as indicating that rare (single atom) N-bound NCS bridges occur in this manganese(II) species." " ... 

Fig. 6). The dinuclear complex displays an intense absorption band in its visible spectra. [The Mn(II) is not expected to contribute significantly to the visible spectrum, as Mn(II)(phenoxide)2 is an amorphous, white polymer (144)]. These two complexes represent the first well-characterized high-valent Mn-phenoxide complexes. Note also that in the structures of the biphenoxide complexes, the benzene rings of each half of the biphenoxide ligands are oriented such that no conjugation is present and each half of the ligand is similar, electronically, to phenoxide. 

The absorption spectra of the free ligand 10 and its mono- and dinuclear complexes Cu.lO, CuCu.lO, CuAg.lO, CuZn-lO " ", CuZn.lO, are reported in Ref. [64] these spectra are well-matched with the sum of the spectra of the two chromophoric (M.5" -type) component units. The luminescence properties of all [3]catenates at 298 and 77 K in CH2CI2 are reported in Table 10. 

The cationic dinuclear complex [/ -0(TcOCl(terpy))2]" was synthesized by reaction of excess terpyridine with [TcOCU] in refluxing ethanol. The blue-violet chloride precipitate is soluble in DMF and DMSO. IR absorptions at 679 and 936 cm arc ascribed to v(Tc-O-Tc) and v(Tc=0), respectively [185]. 

One of the most powerful methods of evaluating the properties of mixed-valence complexes is spectroelectrochemistry. A key experiment is to reversibly cycle a dinuclear complex through fully oxidized, mixed-valence and fully reduced states. A near IR absorption band that appears only in the electronic spectrum of the mixed-valence state is strong evidence for an intervalence transition. Determination of the nature of the mixed-valence state can also be achieved by spectroelectrochemical methods. 

The electronic absorption data for the polyaammineruthenium dinuclear complexes were obtained by spectroelectrochemical studies, using an optically transparent, thin-layer electrochemical (OTTLE) cell. It is important that the effect of electrochemical titration on the... 

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