Matrix Isolation FTIR and Theoretical Study of Weakly Bound Complexes of Isocyanic Acid with Nitrogen

Weak complexes of isocyanic acid (HNCO) with nitrogen were studied computationally employing MP2, B2PLYPD3 and B3LYPD3 methods and experimentally by FTIR matrix isolation technique. The results show that HNCO interacts specifically with N2. For the 1:1 stoichiometry, three stable minima were located on the potential energy surface. The most stable of them involves a weak, almost linear hydrogen bond from the NH group of the acid molecule to nitrogen molecule lone pair. Two other structures are bound by van der Waals interactions of N⋯N and C⋯N types. The 1:2 and 2:1 HNCO complexes with nitrogen were computationally tracked as well. Similar types of interactions as in the 1:1 complexes were found in the case of the higher stoichiometry complexes. Analysis of the HNCO/N2/Ar spectra after deposition indicates that the 1:1 hydrogen-bonded complex is prevalent in argon matrices with a small amount of the van der Waals structures also present. Upon annealing, complexes of the 1:2 and 2:1 stoichiometry were detected as well.

Guenther Maier

Done—Memories of a PhD Supervisor GUENTHER MAIER, born in 1932, was fascinated early on by “impossible molecules”. Whether in Karlsruhe, Baltimore, Marburg, or Giessen, he always wanted to overcome new challenges. Tetrahedrane, molecule of the year 1978, became his trademark. The author employs short, chronological accounts to trace and reflect on his chemical pathways and detours, his role models, his collaboration with colleagues, and his life. He opens up a world of exotic molecules through experiments—photochemistry, flash pyrolysis, low-temperature matrix isolation—and theory. Curiosity, luck, and imagination, but also persistence, uncover many secrets.