Chiral Crystal Structure of a <i>P</i>2₁2₁2₁ Kryptoracemate Iron(II) Complex with an Unsymmetric Azine Ligand and the Observation of Chiral Single Crystal Circular Dichroism

A chiral complex, [Fe­(HL)₂]­(PF₆)₂ (<b>1</b>), where HL denotes 2-pyridylmethylidenehydrazono-4-(2-methylimidazolyl)­methane, was prepared. X-ray structure analysis revealed that it crystallizes as a kryptoracemate of sesquihydrate chiral crystals in the orthorhombic noncentrosymmetric space group <i>P</i>2₁2₁2₁ (<i>Z</i> = 8, <i>Z</i>′ = 2). Two diastereomeric cationic complexes with opposite configuration reside within the asymmetric unit. KBr pellets prepared using selected single crystals showed enantiomorphous circular dichroism patterns