Crystal structures of H2[Me2dibenzo[14]tetraene]N4 and H2[Me2dixylyl[14]tetraene]N4: new tetraaza macrocycles

Abstract

Crystal structures are reported for H₂[Me₂dibenzo[14]tetraene]N₄(I) and H₂[Me₂dixylyl[14]tetraene]N₄(II), prepared by the condensation of o-phenylenediamine and dimethyl-o-phenylenediamine with 3-ethoxy-2-methylacrolein in dimethylformamide. The space groups are P2₁/n, with cell constants of a= 9.940(4)Å, b= 5.242(2)Å, c= 15.329(5)Å, B= 94.01 (3)°, Z= 2 for I, (C₂₀H₂₀N₄), and a= 7.309(1)Å, b= 13.712(2)Å, c= 10.010(3)Å, B= 90.61(2)°, Z= 2 for II, (C₂H₂₈N₄). The macrocycles possess a near-planar structure with the largest deviation of any non-hydrogen atom from the least-squares molecular plane being 0.117 Å for macrocycle I. The N-to-centre distance (R_H) of 1.92 Å found in both I and II is smaller than that found in porphyrins and non-conjugated N₄ 14-membered macrocyclic rings such as cyclam, but very similar to the value found in phthalocyanines.