The carboxylate ligand-exchange reaction of copper(I) trifluoroacetate by 3,5-difluorobenzoate yielded a new product, [Cu(O2C(3,5-F)2C6H3)] (1). Single crystals of 1 suitable for X-ray structural characterization were obtained by sublimation-deposition procedures at 230 degrees C. An X-ray diffraction study revealed a remarkable planar hexanuclear copper(I) core supported by bridging carboxylates, the first such structural type among other known copper(I) carboxylates. The Cu...Cu distances within the core range from 2.7064(8) to 2.8259(8) A and fall into the category of cuprophillic interactions. The hexacopper unit remains intact upon gas-phase deposition with a planar polyarene, coronene (C24H12), to give [Cu6(O2C(3,5-F)2C6H3)6](C24H12) (2). Density functional theory calculations suggest the latter compound to be a cocrystallization product having electrostatic interactions between the hexacopper complex and coronene. However, cocrystallization affects the photophysical properties of 2. While copper(I) 3,5-difluorobenzoate (1) exhibits photoluminescence at ca. 554 nm (lambda(ex) = 350 nm) in the solid state, compound 2 is nonluminescent at room temperature in the visible region. Gas-phase and solution reactions of 1 with alkyne ligands, diphenylacetylene (C14H10) and 1,4-bis(p-tolylethynyl)benzene (C24H18), result in the rupture of the [Cu6] core to afford dinuclear organometallic copper(I) complexes. The latter have a dimetal core cis-bridged by two carboxylate groups with acetylene ligands eta(2)-coordinated to each copper(I) center.

A hydrocarbon that has three separate aromatic rings, namely 1,4-bis(p-tolylethyl)benzene (C 24 H 26 ), 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, [Rh 2 (O 2 CCF 3 ) 4 ], affords single crystals of a novel organometallic complex, [Rh 2 (O 2 CCF 3 ) 4 ] 2 ‚(C 24 H 26 ). The product has a ladder type structure built on weak but directional rhodium(II)-π-arene interactions. In the above framework, each C 24 H 26 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.