The Characterization and Isomerization of η2-Naphthalene and η2-Phenanthrene Complexes of Pentaammineosmium(II)

A series of substituted-naphthalene complexes have been synthesized of the form [Os(NH₃)₅(η²-L)](OTf)₂ (where L = 1-methylnaphthalene, 2-methylnaphthalene, 2-methoxynaphthalene, 2-hydroxynaphthalene, 1-methoxynaphthalene, 1-hydroxynaphthalene, 1-acetonaphthone, 2-acetonaphthone, and phenanthrene), with two or more linkage isomers identified for several of these complexes. The ratio of these isomers changes over time in solution (acetone-d₆) and eventually reaches dynamic equilibrium. The final equilibrium ratios and the associated specific rates are reported. In several cases, protonation of an isomer mixture generates a single naphthalenium species, which upon deprotonation provides the original η²-naphthalene complex as a single set of ring isomers.