A series of new cyclopenta-fused triphenylenes has been synthesized in high yield and reacted with [Ru(μ 3 -Cl)Cp*] 4 to form [RuCp*(η 6 -arene)]PF 6 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 η 5 -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. ■ INTRODUCTIONCyclopentadienyl (Cp, η 5 -C 5 H 5 ) and pentamethylcyclopentadienyl (Cp*, η 5 -C 5 Me 5 ) ruthenium complexes with arene ligands have been extensively studied, forming η 6 -sandwich complexes of the type [RuCp(η 6 -arene)] + and [RuCp*(η 6 -arene)] + that are generally stable under atmospheric conditions. 1−7 The [RuCp*] + fragment is known to strongly interact with aromatic hydrocarbons with a high tolerance to functional groups. 3 The resulting ruthenium sandwich complexes have been studied for their interesting electrochemical and spectroscopic properties, as well as their catalytic activity. 8,9 The most popular synthetic route toward simple [RuCp*(η 6 -arene)] + complexes involves the formation of a [RuCp*-(CH 3 CN) 3 ] + complex, which is reacted with the appropriate arene ligand with heating or UV irradiation. 2,5,10 These methods are generally useful and robust; however, the need for toxic or expensive Sn and Ag reagents leaves room for improvement. In 2007 Fairchild et al. 5 proposed a slightly altered route to these target [RuCp*(η 6 -arene)] + complexes that involves the direct reaction of [Ru(μ 3 -Cl)Cp*] 4 , a precursor in previous pathways, with the arene and the aid of microwave irradiation. The water-soluble chloride salt of the resultant complex was obtained after short reaction times in high yields, and the reaction was shown to be reliable for a wide range of arene ligands. However, the arene ligands studied were mostly single ring benzene derivatives, naphthalene and quinoline being the exceptions, with the [RuCp*] + forced to bind to the only arene ring present.Site selectivity for complexation of [RuCp*] + to substituted polyaromatic systems has been little studied. Previous work 1,6,11,12 gives some precious insight into the affinity of the [RuCp*] + fragment for a range of mostly monosubstituted simple arene systems. Larger polycyclic aromatic hydrocarbon (PAH) ligands that complex [RuCp*] + have all been unsubstituted. 13,14 To the best of our knowledge, no reports to date describe the site selectivity of [RuCp*] + for PAHs with a range of substitution patterns and types. Furthermore, the presence of a peripheral cyc...

Hexa‐peri‐hexabenzocoronenes with a bay‐fused five‐membered ring are synthesized from fluorenyl precursors. The key oxidative cyclodehydrogenation step is accompanied by regioselective chlorination that is enhanced by methylation at the cyclopenta‐ring or increased reaction concentration. The CpHBC products undergo mild electrophilic aromatic bromination, without catalyst, to afford adducts suitable for π‐extension by cross‐coupling.