Synthesis and crystal structures of 6- and 8-methyl-3-phenyl­benzo[e][1,2,4]triazines

Abstract

The crystal structures of two Blatter radical precursors, 6-methyl-3-phenyl­benzo[e][1,2,4]triazine and 8-methyl-3-phenyl­benzo[e][1,2,4]triazine, exhibit extended conjugated heteroaromatic frameworks, with unidimensional columnar arrangements governed by π–π stacking inter­actions with little impact from the methyl substituent position on the core geometry.

The synthesis and single-crystal X-ray structures of two regioisomeric Blatter radical precursors, 6-methyl-3-phenyl­benzo[e][1,2,4]triazine, (I), and 8-methyl-3-phenyl­benzo[e][1,2,4]triazine (II), C₁₄H₁₁N₃, are reported. Both compounds feature planar heteroaromatic frameworks with extensive π-conjugation across the benzo[e][1,2,4]triazine core. Compound I crystallizes in the ortho­rhom­bic space group Pbca, while II adopts the monoclinic space group P2₁/c. Structural analysis reveals nearly identical bond lengths and angles across both isomers, indicating minimal influence of methyl substitution on core geometry. Supra­molecular features are dominated by π–π stacking inter­actions, leading to one-dimensional columnar arrangements. Compound I exhibits alternating dimers with slippage in both stacking directions and forms hydrogen-bonded chains that generate dense, wave-like sheets. Compound II displays uniform stacking with regular inter­planar distances and pronounced translational overlap. These structural insights contribute to understanding how regioisomeric substitution patterns influence the solid-state organization of Blatter radical precursors, with implications for their application in mol­ecular electronics and spin materials.