Consequently, the addition of one equiv. of 14 does not lead to the formation of the triad. The observed red fluorescence originates from the direct excitation of the red Bodipy at 423 nm (crosstalk). Additional evidence for this interpretation comes from the fact that this red fluorescence intensity is virtually the same as the one produced by a c= 5.0 • 10 -6 mol/L solution of 14 in 1,2dichloroethane. Consequently, in the cross-talk and self-absorbance corrected data set, the red emission is almost unchanged (fig. ). To better understand the absence of triad formation after addition of one equiv. of 14, the reaction of [Au(NTf2)(IPr)] with a single equivalent of dbu was probed by 1 H-NMR spectroscopy. Upon addition of one equivalent of dbu to a solution of [Au(NTf2)(IPr)] in CDCl3 several 1 H-and C-NMR signals of the dbu experience significant shifts. Based on this, it is concluded that dbu forms a complex with the cationic gold, which explains why the triad is not formed after addition one equivalent of complex 14. Based on highly sensitive fluorescence spectroscopy FRET pairs are shown to be a powerful tool to establish connectivities. This will also be useful for the detection of dinuclear intermediates or dinuclear decomposition products in homogeneous catalysis, which likely occur in several very important transition metal catalyzed reactions: For the copper-catalyzed click reactions Fokin et al. demonstrated the intermediate formation of dinuclear copper complexes. In olefin metathesis Grubbs et al. were able to identify a dinuclear ruthenium complex as a catalyst decomposition product and bimolecular decomposition appears to be a major catalyst decomposition pathway in olefin metathesis. In Pd-catalyzed cross coupling reactions dinuclear precatalysts and intermediates appear to be highly significant as well. The small amount of catalyst used in such reactions and/or the small amount of binuclear species formed, renders their direct observation difficult -especially in the absence of a unique spectroscopic signature of such bimetallic species. The methodology presented here, should enable the direct observation of such intermediates via FRET and should facilitate the determination of the respective kinetics.