The variability of hydrogen-bonded supramolecular assemblies in crystalline picrates prepared from ferrocenyl-substituted β-aminoalcohols

Abstract

Ferrocene-based β-aminoalcohols FcCH 2NHCR 2CH 2OH (R = H, 1a; R = Me, 1b) and ( S)-FcCH 2NHCH(CHMe 2)CH 2OH ( 1c; Fc = ferrocenyl) react with 2,4,6-trinitrophenol (Hpic) under proton transfer to afford the corresponding ammonium picrates 2a– c. In the crystal, these picrates associate predominantly via N–H⋯O and O–H⋯O bifurcated hydrogen bonds between the NH 2 + and OH groups in the aminoalcohol chain as the donors and the phenoxide and NO 2 oxygen atoms of the picrate anion as the acceptors. Compounds 2a and 2b form closed dimeric assemblies [ 1nH] 2[pic] 2 ( n = a, b) around the crystallographic inversion centres. By contrast, their chiral analogue 2c gives rise to monomeric units [ 1cH][pic] (albeit through similar interactions), that further aggregate into infinite linear chains via N–H⋯O hydrogen bonds. The formed assemblies are interconnected by the soft C–H⋯O hydrogen bonds and via π⋯π stacking interactions of the picrate ions.