Crystal Structure of the Chiral Iron(II) Δ-[FeCl{(R,R)-Me-Duphos(O)₂}₂](BF₄)·CH₂Cl₂ Compound

(being prepared for publication)

The development of sustainable catalysts is key in green chemistry to reduce environmental impact. More concretely, iron oxophosphine compounds are of great interest in green chemistry mainly because of the high abundance of iron in the Earth's crust and the high air stability of oxophosphine ligands. In enantioselective homogeneous catalysis, designing iron compounds with enantiopure oxophosphines is highly attractive. In this work, the molecular structure of Δ-[FeCl{(R,R)-Me-Duphos(O)₂}₂](BF₄)·CH₂Cl₂ is reported. This compound was formed by O₂-promoted oxidation of the [FeH(η²-H₂){(R,R)-Me-Duphos}₂]⁺ complex in dichloromethane and identified crystallographically. The compound crystallizes in the monoclinic and non-centrosymmetric P2₁ space group a= 9.6736(3) Å, b=21.4227(6) Å, c= 11.6065(3) Å, α=γ=90º,  β =109.487(3), V=2267.49(12) ų, Z=4. The structure contains a pentacoordinated Fe(II) cation, a BF₄^- anion, and a molecule of CH₂Cl₂. The cation shows a κ⁴O,κCl coordination environment within a distorted square pyramidal geometry. This structure was compared with those of related compounds and with the structure obtained from density functional theory (DFT) calculations. To gain deeper insight into the bonding interactions within the iron compound, crystal packing, Hirshfeld surface analyses, and two-dimensional (2D) fingerprint plots were conducted. The findings reveal that the crystal packing is predominantly influenced by van der Waals interactions and weak to moderate H⋯H and halogen⋯H contacts, which do not play a significant role in the compound's structural configuration. Overall, we report the first example of an enantiomerically pure iron compound bearing the chiral (R,R)-Me-Duphos(O)₂ ligand, isolated as an enantiomerically pure crystal.