А crystallographic and theoretical study of intermolecular interactions of newly synthesized spirohydantoins

Abstract

A series of spirohydantoins derived from α-tetralone (Figure 1) was synthesized and the compounds were characterized using the melting point measurements, FTIR, 1H and 13C NMR spectroscopic methods. The molecular conformation, crystal packing properties and intermolecular interactions of 1-(4-methoxybenzyl)-3’,4’-dihydro-2Hspiro[ imidazolidine-4,1’-naphtalene]-2,5-dione were analyzed by single crystal X-ray diffraction and quantum chemical calculations. The crystal packing of this compound (monoclinic, P21/c, a = 12.682(3), b = 6.4568(13), c = 20.826(4) Å, β = 98.61(3) °, R = 4.3%) contains centrosymmetric dimmers linked by N–H···O hydrogen bonds, which are further connected via C–H···O, C–H···π and parallel interactions of the phenyl rings at a large offset (PILO) to form infinite pseudo-layers. As a result, the pseudo-layers are associated into highly ordered three-dimensional framework along the b-axis. By combination of the crystal packing analysis and quantum chemical calculations, it was concluded that the structural motif formed by N–H···O hydrogen bonds between hydantoin rings is the most stable in the crystal structure. It was shown that the introduction of an electron-donating substituent into the benzyl moiety leads to strengthening of N–H···O hydrogen bonds, while an electron-accepting substituent has the opposite effect. The introduction of substituents enhances the stacking, C–H···π and PILO interactions, so it is expected that PILO interactions are the most represented in the crystal structures, as shown by statistical analysis of crystal structures of benzene molecules from Cambridge Structural Database.[1] Figure 1. The chemical structure of the investigated compounds.