[2.2]Paracyclophanes with N-Heterocycles as Ligands for Mono- and Dinuclear Ruthenium(II) Complexes

[2.2]Paracyclophane, with its unique structure, allows the design of unusual 3D structures by functionalization of this rigid and stable hydrocarbon scaffold. Therefore different mono- and homodisubstituted [2.2]paracyclophanes with pyridyl, pyrimidyl and oxazolinyl substituents were developed in order to evaluate their ability as bridging ligands for two ruthenium centres. With the successfully synthesized [2.2]paracyclophane-based N-donor functions, the cycloruthenation reaction using [RuCl₂ (p-cymene)]₂ as precursor was explored. Compared to 2-phenylpyridine, the [2.2]paracyclophane derivative is clearly inferior in the cycloruthenation reaction, resulting in poor yields for the neutral complexes. By addition of KPF₆ , the cationic complexes can be obtained in good yields and are formed diastereoselectively in case of a pyridyl substituent, resulting in only one diastereomer for dinuclear ruthenium complexes of bispyridyl-substituted [2.2]paracyclophanes as bridging ligands.