Crystal structures of two new six-coordinate iron(III) complexes with 1,2-bis(diphenyl-phosphane) ligands.

Structural characterization of the ionic complexes [FeCl(CHP)][FeCl]·0.59CHCl or [(dppen)FeCl][FeCl]·0.59CHCl (dppen = -1,2-bis-(di-phenyl-phosphane)ethyl-ene, PCH) and [FeCl(CHP)][FeCl]·CHCl or [(dpbz)FeCl][FeCl]·CHCl (dpbz = 1,2-bis-(di-phenyl-phosphane)benzene, PCH) demonstrates coordination of two bidentate phosphane ligands (bis-phosphanes) to a single iron(III) center, resulting in six-coordinate cationic complexes that are balanced in charge by tetra-chlorido-ferrate(III) monoanions. The bis-phosphane coordination is consistent will all previously reported mol-ecular structures of six coordinate iron(III) complex cations with a (PP) ( = halido) donor set. The complex with dppen crystallizes in the centrosymmetric space group 2/ as a partial-occupancy [0.592 (4)] di-chloro-methane solvate, while the dpbz-ligated complex crystallizes in the triclinic space group 1 as a full di-chloro-methane monosolvate. Furthermore, the crystal studied of [(dpbz)FeCl][FeCl]·CHCl was an inversion twin, whose component mass ratio refined to 0.76 (3):0.24 (3). Beyond a few very weak C-H⋯Cl and C-H⋯π inter-actions, there are no significant supra-molecular features in either structure.