Natural cocrystallisation of two ferrocenyl compounds

Abstract

In the reaction of H₂N–NC(CH₃)–C(CH₃)N–OH (L) with ferrocenecarboxaldehyde (FCAL) in methanol, the 1∶1 condensate 1a of L and FCAL crystallises with the 2∶1 condensate 1b of FCAL and hydrazine to form the cocrystal 1. In 1, 1a∶1b = 2∶1. The cocrystal is characterised by single crystal X-ray crystallography, ¹H NMR and cyclic voltammetry. 1 is centrosymmetric (spacegroup P2₁/c). While 1b can be prepared easily in pure form, it seems that 1a cannot crystallise in pure form.