Inorganic Chemistry, Vol.50, No.6, 2545-2552, 2011
Study of the Conformationally Flexible, Wide Bite-Angle Diphosphine 4,6-Bis(3-diisopropylphosphinophenyl)dibenzofuran in Rhodium(I) and Palladium(II) Coordination Complexes
The diphosphine 4,6-bis(3-diisopropylphosphinopheny)dibenzofuran (abbreviated as (iPr)DPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [((iPr)DPDBFphos)Rh(NBD)BF4, which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitile) complexes of rhodium and palladium [((iPr)DPDBFphos)M(CH3CN)(2)](BF4)(n) (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions.