Rhodium-ruthenium assembly

Numerous studies aimed at the understanding of the mechanism of these processes rapidly appeared. In this context, Murai examined the behavior of acyclic linear dienyne systems in order to trap any carbenoid intermediate by a pendant olefin (Scheme 82).302 A remarkable tetracyclic assembly took place and gave the unprecedented tetracyclo[6.4.0.0]-undecane derivatives as single diastereomer, such as 321 in Scheme 82. This transformation proved to be relatively general as shown by the variation of the starting materials. The reaction can be catalyzed by different organometallic complexes of the group 8-10 elements (ruthenium, rhodium, iridium, and platinum). Formally, this reaction involves two cyclopropanations as if both carbon atoms of the alkyne moiety have acted as carbenes, which results in the formation of four carbon-carbon bonds. 

The construction of well-defined DNA assemblies containing donors and acceptors at discrete sites on the helix allows the probing of DNA as a model of molecular wire. Barton et al. have designed a DNA duplex with a [Ru(bpy/phen)2(dppz)]2+ derivative as an electron donor and [Rh(phi)2(bpy/phen)]3+ derivative as an electron acceptor tethered by flexible linker to the opposite ends of the assembles [91,96, 97]. Both complexes were free to intercalate but separated by a fixed distance. The intercalation sites for both complexes were characterized by employing duplex DNA bearing a tethered ruthenium or rhodium complex. For ruthenium complexes... 

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