Elucidation of the Structure and Fluxionality of a Dinuclear Organometallic Complex Reluctant to Crystallize: An Experimental and Theoretical Integrated Approach

The organometallic dication 12+ has been constructed by combining the angular py-functionalized ligand N,N’-bis-(3- aminopyridine)-1,4,5,8-naphthalenetetracarboxydiimide (L) with [(p-cymene)RuCl] moieties. In 12+ two ligands L bridge two organometallic nodes. Repeated crystallization attempts of 12+ failed and then a combined DFT/VT-1HNMR/UV-Vis spectroscopy study has been performed to define the most plausible structure of the dication. These considers the two naphthalenediimide platforms unstacked, thus giving rise to a very open conformation where the two chloride and the two p-cymene ligands lye on the same side of the cationic cleft. The high fluxionality of 12+ evidenced by 1HNMR spectroscopy has been elucidated by a combined PES (Potential Energy Surface)/MD (Molecular Dynamic)/DFT-GIAO (Gauge Including Atomic Orbitals) study, thus furnishing a detailed description of the dynamic character of 12+.