Site Selectivity of [RuCp*]+ Complexation in Cyclopenta[def]triphenylenes

A series of new cyclopenta-fused triphenylenes has been synthesized in high yield and reacted with [Ru­(μ3-Cl)­Cp*]4 to form [RuCp*­(η6-arene)]­PF6 complexes. Systematic variation of the cyclopenta­[def]­triphenylene allowed the site of complexation to be probed and the influence of the electronic and steric properties of the substituents in directing complexation to be assessed. As determined by NMR spectroscopy and X-ray crystallography, in all cases the [RuCp*]+ fragment complexes at a peripheral arene ring, rather than at the central arene ring or as a neutral η5-cyclopentadienyl metallocene adduct. It was shown that electronic influences are minimal, while steric effects afford selective complexations. The electronic properties of the ligands and complexes were probed with electrochemistry, along with electronic absorption and emission spectroscopies.