Molecular Structure of 1,3,5-Triazine in Gas, Solution, and Crystal Phases and by ab Initio Calculations

The r α, r 0, and r s structures of 1,3,5-triazine ( 12 C 3 14 N 3 H 3 ) have been determined in the gas phase by analysis of electron diffraction data and high-resolution FTIR spectra, including those for the isotopomers 12 C 3 15 N 3 H 3, 13 C 3 14 N 3 H 3, 13 C 3 15 N 3 H 3, and 12 C 3 14 N 3 D 3, in solution in liquid crystal solvents by NMR spectroscopy, and by ab initio calculations. Combining gas- and solution-phase data in a single analysis yields a very precise structure, with final parameter values ( r α °) r (C−N) 133.68(1) pm, r (C−H) 108.9(2) pm, and ∠(CNC) 113.82(9)°. The final structure obtained is also compared with the crystal structure.