Proton affinities of amino group functionalizing 2D and 3D boron compounds

0500424 - ÚACH 2019 RIV ES eng J - Journal Article
Oliva-Enrich, J. M. - Humbel, S. - Dávalos, J. Z. - Holub, Josef - Hnyk, Drahomír
Proton affinities of amino group functionalizing 2D and 3D boron compounds.
Afinidad. Roč. 75, č. 584 (2018), s. 260-266. ISSN 0001-9704. E-ISSN 2339-9686
Institutional support: RVO:61388980
Keywords : Proton affinity * metallaheteroborane * superacid * quantum chemistry * delocalization energy * DFT
OECD category: Inorganic and nuclear chemistry
Impact factor: 0.263, year: 2018

We report quantum-chemical computations of Proton Affinities (PA) of icosahedral amino boranes, carboranes and Co-containing metallacarboranes with a relative error of similar to 2% when experimental data available by means of the B3LYP and BP86 functionals. Use of larger basis sets for simple systems such as NH3, CH3NH2, and borazine (B3H6N3) reduces the error to similar to 0.5 % indicating the validity of these functionals for these computations and prediction of PA for unavailable experimental data on amino-derived (car) boranes and metalla(car)boranes. The computed PA show that, from an electronic structure point of view, when substituting an exo H atom by an NH2 group in B12H12(2-), CB11H12(-), (ortho, meta, para)-C2B10H12, and the metallacarborane [3-Co(1,2-C2B9H11)(2)]((-)) = COSAN the most similar system to be compared with is the anion NH2-BH3(-) computed PA(B3LYP/cc-pVTZ) = 1505 kJ.mol(-1) rather than methylamine CH3NH2 or borazine, the two latter with experimental PA of 900 and 803 kJ.mol(-1) respectively. The largest PA for a given isomer correspond, following this order, to: 1-NH2-B12H11(2-), (-)BH3NH2, 12-NH2-CB11H11(-), cisoid 8-NH2-COSAN, transoid 9-NH2-COSAN, 9-NH2-1,2-C2B10H11, 9-NH2-1,7-C2B10H11, and 2-NH2-1,12- C2B10H11. The rule for larger PA applies for isomers with the NH2 groups farthest aways from (non-metal) carborane C(cage) atoms. Pyramidalization energy computation shows an enhanced facility for planarization of the amino group in cisoid 8-NH2-COSAN as compared to cisoid 1-NH2-COSAN.
Permanent Link: http://hdl.handle.net/11104/0292504