Gas-Phase Assembling of Dirhodium Units into a Novel Organometallic Ladder:  Structural and DFT Study

A hydrocarbon that has three separate aromatic rings, namely 1,4-bis(p-tolylethyl)benzene (C₂₄H₂₆), has been structurally characterized for the first time and tested as an elongated aromatic π-donor in assembling reactions under solvent-free conditions. Its gas-phase interaction with the electrophilic dimetal complex, [Rh₂(O₂CCF₃)₄], affords single crystals of a novel organometallic complex, [Rh₂(O₂CCF₃)₄]₂·(C₂₄H₂₆). The product has a ladder type structure built on weak but directional rhodium(II)−π-arene interactions. In the above framework, each C₂₄H₂₆ exhibits a tetradentate-bridging coordination having four rhodium(II) centers attached to the opposite sides of the two peripheral benzene rings. The underlying reasons for such coordination defining the formation of the title product have been discussed based on the results of density functional theory, namely the orbital interaction analysis of the reacting partners.