Studies of substituted quinoxaline-di-N-oxides. Part 1. Crystal structure and molecular conformation of 2-[N-(2-hydroxyethyl)carboxamide]-3-methylquinoxaline 1,4-dioxide

Abstract

A single crystal X-ray investigation of the yellow 2-[N-(2-hydroxyethyl) carboxamide]-3-methylquinoxaline 1,4-dioxide, a commercially available growth promoter used in agricultural stock farming, shows that the molecule is planar. The dihedral angle between the benzene and heterocyclic rings is 0.5°. The N(1)-O(1) and N(2)-O(2) distances are: 1.286(1) and 1.304(1) Å. The C(1)-C(2) bond of the pyrazine ring is not lengthened by substitution at the C(1) and C(2) atoms and is 1.421(2) Å. The atoms O(1) and O(2) deviate by 0.036(2) and 0.123(2) Å from the least-squares plane through the heterocyclic ring. The deviation of the C(12) atom is −0.012(2) Å. The plane through the atoms C(1), C(9), N(3), and O(3) makes an angle of 100.5(2)° with the heterocyclic ring plane. Intermolecular hydrogen bonds O(4)-HO(4)⋯O(3) between the hydroxyl and carbonyl groups generated alternating, antiparalled chains extending in thea direction. The crystals are triclinic,P¯1 (No. 2), witha=7.469(2),b=8.111(2),c=10.357(3) Å,α=80.11(2),β=88.90(2), γ=67.73(2)°, andV=571.3(2) ų. The structure was solved by direct phase determination guided by negative quartets and refined by full-matrix least squares to anR value of 0.041 for 2159 observed reflections.