The scope and limitations of cyanide groups as direction labels for the conformational analysis of matrix-isolated molecules of low symmetry: Part 2: 3-Cyanophenyl azide and two conformationally restrained derivatives

Abstract 3-Cyanophenyl azide and derivatives with ortho methyl groups were photolysed with plane-polarized light in N 2 matrices at 12–20 K. The resulting matrices containing the methyl-substituted derivatives had pronounced IR linear dichroism which was interpreted in a qualitative way to identify the predominant conformers of the matrix-isolated azides. The cyano groups functioned as direction labels , aiding the analysis of the results. Despite problems of band overlap with CN stretches, it was determined, to a high degree of probability, that phenyl azides with one ortho substituent exist in N 2 matrices predominantly as the anti conformer. In contrast, 3-cyanophenyl azide could not be photo-oriented in N 2 matrices to a significant or reproducible extent, which supports the expectation that the syn and anti conformers of this azide are virtually equal in energy and thus co-exist in comparable amounts.