Molecular structure of N-methylpyrrole studied by gas electron diffraction using rotational constants and liquid–crystal NMR spectroscopy

Abstract

The molecular structure of N-methylpyrrole has been reinvestigated by gas electron diffraction using the rotational constants of 13C- and 15N-substituted species of N-methylpyrrole and N-methyl-d3-pyrrole measured by Huber et al. [J. Mol. Struct. 413–414 (1997) 93]. The resulting structural parameters (rz (Å) and ∠z (°)) with the estimated limits of error (3σ) are: r(N–Cring)=1.372(6), r(N–CMe)=1.425(7), r(CC)=1.383(9), r(C–C)=1.425(11) 〈r(C–H)〉=1.088(4), ∠CNC=109.3(9), ∠NCC=108.2(7), ∠CCC=107.1(4), ∠NCHring=117.7(29), ∠HCC(N)=124.0(42), ∠HCH=109.1(3), where 〈〉 denotes an average value. The molecular structure, including carbon positions, of N-methylpyrrole dissolved in liquid crystal, ZLI 1167, has been determined by analyzing the 1H NMR spectrum with 13C satellites. The results show that the molecular structure in ZLI 1167 agrees with that in the gas phase within experimental uncertainties.