Synthesis and characterization of a biferrocene with a fulvalene ligand

Inorg. Chem. 1989, 28, 4160-4165

4160

Contribution from the Department of Chemistry, D-006,University of California at San Diego, La Jolla, California 92093, and the School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801

Synthesis and Characterization of a Biferrocene with a Fulvalene Ligand Fused into a Cis Conformation: X-ray Structure of N,N-Dimethyl-2,5"-(2-azoniapropane-1,3-diyl)biferrocene Pentaiodide Wei Zhang,l Scott R. Wilson,' and David N. Hendrickson*%* Received September 7, I988 The preparation and characterization of the first side-by-side fused biferrocenes are reported. 2,5"-Bis((dimethy1amino)methy1)biferrocene was used to prepare N,N-dimethyl-2,5"-(2-azoniapropane-1,3-diyl)biferroceneiodide (12). Reaction of 12 with I2 in solution gives the analogous pentaiodide salt N,N-dimethyl-2,5"-(2-azoniapropane1,3-diyl)biferrocenepentaiodide (17). Reaction of 12 with L ~ B H ( s ~ c - B gives u ) ~ the nonsalt fused biferrocene N-methyl-2,5"-(2-azapropane-1,3-diyl)biferrocene (13). Results from the X-ray structure of 17 show that this I< salt crystallizes in the orthorhombic space group Pbca with eight formula units in a cell having the dimensions a = 16.087 (6)A, b = 17.796 (6)A, and c = 20.839 (10)A. Discrete 1,- anions and Fe1Iz ammonium cations are present. The fulvalenide ligand has a CH2-N(CH3)2CH2- moiety fused between the 2-and 5"-positions. He-H contacts in the cation lead to a 38.4O dihedral angle in the fulvalenide ligand. The cation can be described as two ferrocene moieties fused together in a side-by-side fashion with Fe.-Fe = 4.571 (3) A. 57FeMossbauer data for 12,13,and 17 show that these molecules are Fellz compounds. The Fe1$ cations in 12 and 13 are not easily oxidized. Complex 13 in CH3CN shows two one-electron reversible oxidation waves at 252 and 616 mV vs Ag/AgCI. The separation between the two waves in 13 is greater than that reported for the two waves for biferrocene in CH3CN. Chemical oxidation of 13 with 12, DDQ, or ferrocenium hexafluorophosphate in solution gives an I-lolo s-I for 1 a n d 2 a t 4.2 K t o a rate