MOLECULAR-GEOMETRY OF 2-NITROTOLUENE FROM GAS-PHASE ELECTRON-DIFFRACTION AND QUANTUM-CHEMICAL STUDY

The molecular geometry of 2-nitrotoluene has been determined by gas ph ase electron diffraction and quantum chemical computations at the MP2/ 6-31G and Becke3-Lee-Yang-Parr (B3-LYP)/6-31G* levels of theory. Comp uted differences in C-C bond lengths were utilized as constraints in t he electron diffraction structure analysis. The scaled B3-LYP/6-31G f orce field was used to generate the initial set of vibrational amplitu des. The electron diffraction study yielded the following bond lengths (r(g)) and bond angles: C-1-C-2, 1.405(8) Angstrom; N-O, 1.231(3) Ang strom; C-1-C-7, 1.508(8) Angstrom; C-N, 1.490(9) Angstrom; C-7-C-1-C-2 , 127.3(7)degrees; N-C-2-C-3, 113.8(6)degrees; C-1-C-2-C-3, 124.2(9)de grees; C-6-C-1-C-2, 114.8(6)degrees; C-5-C-6-C-1, 123.1(10)degrees; O- N-O, 124.9(3)degrees; phi(C-N), 38(1)degrees, The structural features of the molecule point to steric interactions prevailing between the me thyl and nitro groups, (C) 1998 Elsevier Science B.V.