Molecular and Crystal Structure of Indole and Camfora with Sterically Hindered Phenol Fragments

Abstract

Molecular and crystal structure of the antioxidant 4-[3,3-bis(3,5-di-tert-butylphenyl-4- hydroxybenzyl)-3H-indole-2-ilmethylene]-2,6-di-tert-butylcyclohex-2,5-dienone (1) and (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N′-((1S,4R)-1,7,7-trimethyl-bicyclo[2.2.1]heptane-2-ylidene)propane hydrazide (2) is studied. It is shown that sterically hindered phenols do not form hydrogen bonds in any of these molecules. In crystal 2, amide groups form a pseudo-centrosymmetric dimer due to N-H…O hydrogen bonds. The chiral camphene basis of molecule 2 prevents the formation of a centrosymmetric supramolecular synthon that usually appears in racemic compounds with amide groups, while the pseudo-centrosymmetric geometry of propane hydrazide chains hinders packing within the space group of the second-order rotational symmetry. As a result, molecules 2 crystallize into non-centrosymmetric crystals with two independent molecules.