Studies of dirhodium(II) tetrakis(trifluoroacetate). Part 8. One-dimensional polymers of Rh-2(O2CCF3)(4) with aromatic ligands: benzene, p-xylene andnaphthalene

The interaction of benzene, p-xylene, and naphthalene with a strong two-end ed Lewis acid, Rh-2(O2CCF3)(4), led to one-dimensional linear polymers of 1 :1 composition, [Rh-2(O2CCF3)(4). L](infinity) where L = C6H6 (1), p -(CH3) (2)C6H4 (2), and C10H8 (3). Compounds 1-3 have been characterized by elemen tal analysis and IR spectroscopy and their structures have been determined by X-ray diffraction. In the crystal structures of the compounds the altern ating arrangement of the dirhodium(II) tetrakis(trifluoroacetate) units wit h the aromatic ligands coordinated to their axial positions forms infinite chains extended along one direction of the unit cell. The rare bridging off -centered, eta(2):eta(2) coordination of arene groups by the Rh(II) centers was found to be preferred in all three cases with the two closest Rh-C-are ne distances averaged to 2.662(6) Angstrom in the benzene complex (1), to 2 .684(7) Angstrom in the p-xylene analogue (2), and to 2.588(9) Angstrom in the naphthalene product (3). (C) 2000 Elsevier Science Ltd. All rights rese rved.