Conformational Analysis of Rotational Barriers in N-Arylpyrrolidin-2-ones

Article abstract of DOI:10.1107/S0108768190012083

The structures of N-phenylpyrrolidin-2-one and the three isomeric N-tolylpyrrolidin-2-ones have been studied by single-crystal X-ray diffraction, as a basis for the conformational analysis of the barrier to rotation around the single bond between the rings.Force-field simulation of the molecular structure is consistent with a rotational barrier of 7 kJ mol^-1.Crystal data: N-phenylpyrrolidin-2-one, orthorhombic, Pbca, a = 14.114 (3), b = 6.879 (4), c = 17.386 (5) Angstroem, R = 0.059 for 1110 unique reflections o<*>4?(F_o)>; N-(2-methylphenyl)pyrrolidin-2-one,orthorhombic, Pbca, a = 16.999 (4), b = 16.411 (2), c = 7.008 (2) Angstroem, R = 0.077 for 1479 unique reflections o<*>4?(F_o)>; N-(3-methylphenyl)pyrrolidin-2-one, monoclinic, P2₁/c, a = 10.411 (2), b = 7.645 (2), c = 12.782 (1) Angstroem, β = 110.32 (1) deg, R = 0.065 for 1641 unique reflections o<*>4?(F_o)>; N-(4-methylphenyl)pyrrolidin-2-one, orthorhombic, P2₁2₁2₁, a = 7.668 (2), b = 10.804 (2), c = 11.456 (1) Angstroem, R = 0.054 for 1155 unique reflections o<*>4?(F_o)>.