Structures of S-(pyridin-2-yl) 4-nitro-benzo-thio-ate, S-(pyridin-2-yl) 4-methyl-benzo-thio-ate and S-(pyridin-2-yl) 4-meth-oxy-benzo-thio-ate: building blocks for low-symmetry multifunctional tetra-pyrroles

Abstract

The crystal structures of three S-(pyridin-2-yl) benzo-thio-esters with varying para-phenyl substituents are presented, namely, S-(pyridin-2-yl) 4-nitro-benzo-thio-ate (1, C₁₂H₈N₂O₃S), S-(pyridin-2-yl) 4-methyl-benzo-thio-ate (2, C₁₃H₁₁NO₂S) and S-(pyridin-2-yl) 4-meth-oxy-benzo-thio-ate (3, C₁₃H₁₁NO₂S). This class of compounds are used in the mono-acyl-ation of pyrrolic species to yield multifunctional tetra-pyrroles. The structures presented herein are the first of their compound class. The dominant inter-actions present in this series are π-π stacking and C-H⋯O inter-actions, and as the para-phenyl motif changes from electron withdrawing (NO₂, 1) to electron donating (OCH₃, 3), changes are observed in the inter-actions present in the crystal packing, from predominant π-π stacking in 1 to exclusively C-H⋯O/N inter-actions (C_ar-yl-H⋯O_carbon-yl, C-H⋯O_meth-oxy and C_ar-yl-H⋯N_pyridine) in 3.

Keywords: benzo­thio­ate derivatives; crystal structure; hydrogen bonding; π–π-stacking.