Photochromic formazans: X-ray crystal structure magnetic resonance and Raman spectra of 3-methyl-1,5-diphenylformazan and 3-t-butyl-l,5-diphenylformazan

Abstract

The X-ray crystal structures of 3-methyl-1,5-diphenylformazan (1) and 3-t-butyl-1,5-diphenylformazan (2) have been determined. Magnetic resonance spectra, in both the solid state and in solution, and Raman spectra have been studied. C₁₄H₁₄N₄(1) belongs to the monoclinic space group P2₁/c, a= 8.133(1), b= 19.085(4), c= 9.364(3)Å, β= 105.93°, U= 1 397.6(5)ų, Z= 4; the anti, s-trans configuration found for the solid state is also the thermodynamically preferred configuration in solution equilibrium. C₁₇H₂₀N₄(2) belongs to the monoclinic space group P2₁/c, a= 11.235(3), b= 20.117(5), c= 14.176(3)Å, β= 92.14(2)°, U= 3 202(1)ų, Z= 8; the syn, s-cis configuration of the solid state is maintained in solution.