Alumazene adducts with acetonitrile: Structure and thermal stability

Lewis acid-base adducts of the inorganic analog of benzene alumazene [{2,6-(i-Pr)(2)C6H3NAlMe}(3)] (1) with acetonitrile (CH3CN, acn) and deuteroacetonitrile (CD3CN, d(3)-acn) were synthesized, spectroscopically characterized, and their molecular structures were elucidated by the X-ray diffraction analysis as a bis-adduct 1(acn)(2) and a tris-adduct 1(d(3)-acn)(3). The thermodynamics of complex formation was investigated experimentally and theoretically. Thermodynamic characteristics of process 1(acn)(3)center dot acn (s) = 1(acn)(2) (s) + 2 acn (g) in the temperature range 294-370 K have been derived from the vapor pressure-temperature dependence measurements by the static tensimetric method. It is shown that above 435 K in the presence of 1 gaseous acn undergoes irreversible polymerization reaction. Quantum chemical computations at B3LYP/6-311G(d,p) level of theory have been performed for the 1(acn)(n) and model complexes of [(HAlNH)(3)] (1m), 1m(acn)(n) (n = 1-3). Obtained results indicate that for the gas phase adducts upon increasing the number of acn ligands the donor-acceptor Al-N(acn) distances increase in accord with decrease of the donor-acceptor bond dissociation energies. (C) 2016 Elsevier B.V. All rights reserved.