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Updated: Feb 8, 2026

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand
Published on: September 8, 2016
Crystal structures of two new six-coordinate iron(III) complexes with 1,2-bis(diphenyl-phosphane) ligands
Derek L McNeil1, Daihlia J Beckford1, Jared L Kneebone1
1Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
Abstract:
Structural characterization of the ionic complexes [FeCl2(C26H22P2)2][FeCl4]·0.59CH2Cl2 or [(dppen)2FeCl2][FeCl4]·0.59CH2Cl2 (dppen = cis-1,2-bis-(di-phenyl-phosphane)ethyl-ene, P2C26H22) and [FeCl2(C30H24P2)2][FeCl4]·CH2Cl2 or [(dpbz)2FeCl2][FeCl4]·CH2Cl2 (dpbz = 1,2-bis-(di-phenyl-phosphane)benzene, P2C30H24) demonstrates trans 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 trans bis-phosphane coordination is consistent will all previously reported mol-ecular structures of six coordinate iron(III) complex cations with a (PP)2X2 (X = halido) donor set. The complex with dppen crystallizes in the centrosymmetric space group C2/c as a partial-occupancy [0.592 (4)] di-chloro-methane solvate, while the dpbz-ligated complex crystallizes in the triclinic space group P1 as a full di-chloro-methane monosolvate. Furthermore, the crystal studied of [(dpbz)2FeCl2][FeCl4]·CH2Cl2 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.
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