title: Complexes of adamantane-based group 13 Lewis acids and superacids: Bonding analysis and thermodynamics of hydrogen splitting.
abstract: The electronic structure and chemical bonding in donor-acceptor complexes formed by group 13 element adamantane and perfluorinated adamantane derivatives EC9 R'15 (E = B, Al; R' = H, F) with Lewis bases XR3 and XC9 H15 (X = N, P; R= H, CH3 ) have been studied using energy decomposition analysis at the BP86/TZ2P level of theory. Larger stability of complexes with perfluorinated adamantane derivatives is mainly due to better electrostatic and orbital interactions. Deformation energies of the fragments and Pauli repulsion are of less importance, with exception for the boron-phosphorus complexes. The MO analysis reveals that LUMO energies of EC9 R'15 significantly decrease upon fluorination (by 4.7 and 3.6 eV for E = B and Al, respectively) which results in an increase of orbital interaction energies by 27-38 (B) and 15-26 (Al) kcal mol(-1) . HOMO energies of XR3 increase in order PH3  < NH3  < PMe3  < PC9 H15  < NMe3  < NC9 H15 . For the studied complexes, there is a linear correlation between the dissociation energy of the complex and the energy difference between HOMO of the donor and LUMO of the acceptor. The fluorination of the Lewis acid significantly reduces standard enthalpies of the heterolytic hydrogen splitting H2  + D + A = [HD](+)  + [HA](-) . Analysis of several types of the [HD](+) ···[HA](-) ion pair formation in the gas phase reveals that structures with additional H···F interactions are energetically favorable. Taking into account the ion pair formation, hydrogen splitting is predicted to be highly exothermic in case of the perfluorinated derivatives both in the gas phase and in solution. Thus, fluorinated adamantane-based Lewis superacids are attractive synthetic targets for the construction of the donor-acceptor cryptands. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Inorganic Chemistry Group, Institute of Chemistry, St. Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russian Federation.
authors.forename: Majid
authors.initials: M
authors.lastname: El-Hamdi
authors.affiliation: Institut De Química Computacional I Catàlisi (IQCC) and Departament De Química, Universitat De Girona, Campus Montilivi, Girona, Catalonia, E-17071, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Solà
authors.affiliation: Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling, Vrije Universiteit Amsterdam, De Boelelaan 1083, Amsterdam, NL-1081HV, the Netherlands.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys, 08010 Barcelona, Catalonia, Spain.|Departament de Química Orgànica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Poater
authors.affiliation: Inorganic Chemistry Group, Institute of Chemistry, St. Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russian Federation.
authors.forename: Alexey Y
authors.identifier: 0000-0002-1932-6647
authors.initials: AY
authors.lastname: Timoshkin
keywords: EDA; aluminum; bonding analysis; boron; donor-acceptor complexes; hydrogen splitting