Rhenium trinuclear compounds

Unlike most metal complexes containing the fa c-(diim i n c) Re1 (CO). unit, which are typically highly luminescent in solution, trinuclear rhenium carbonyl compounds 7 and 8 (see Fig. 11a) show only weak luminescence ( em = 0.0015) in CH3CN at room temperature [36], The quenching appears to occur via intramolecular... 

Reaction of the manganese and rhenium carbonyls, M2(CO)10, with Ru3(CO)12 or Os3(CO)12 in a 3 1 ratio yields the products [M(CO)5]2M (CO)4, with M = Re or Mn, M = Ru or Os. These are considered to be linear trinuclear metal systems. The only other trinuclear carbonyl derivative isolated is OsCo2(CO)n, obtained as one of a number of compounds from the reaction of Co2(CO)8 with H2Os(CO)4. No structural data are available for this compound (241). 

Fig. 11 (a) Trinuclear rhenium carbonyl complexes 7 and 8 and (b) UV-Vis difference spectra (Aabs = At - At = 0) of compound 7 in CH3CN at 293 K after irradiation at 366 nm for 0, 1,2, 3, 4, 6 h, and inset shows the emission spectral changes before and after photolysis (reproduced with permission from [39])... 

Most of the compounds with metal-metal double bonding do not arise directly from the analogue of higher bond order discussed above. Thus for instance in the chemistry of rhenium compounds the best known and also most interesting species are the Re (III) trinuclear clusters that will be discussed in the next chapter. In this sense the chemistry of compounds with metal-metal double bonds appears as a transition from the chemistry of dinuclear metal compounds to that of higher metal aggregates. 

---