The Ever-Surprising Chemistry of Boron: Enhanced Acidity of Phosphine⋅Boranes
作者:Marcela Hurtado、Manuel Yánez、Rebeca Herrero、Andrés Guerrero、Juan Z. Dávalos、José-Luis M. Abboud、Brahim Khater、Jean-Claude Guillemin
DOI:10.1002/chem.200802307
日期:2009.4.27
The acidity‐enhancing effect of BH3 in gas‐phase phosphine⋅boranes compared to the corresponding free phosphines is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. Thus, the enhancement of the acidity of protic acids by Lewis acids usually observed in solution is also observed in the gas phase. For example, the gas‐phase acidities (GA) of MePH2 and MePH2⋅BH3 differ
The rotational spectrum of phosphaethene (CH2PH) was reinvestigated. One hundred and nineteen new lines were measured in the submillimeter range from 500 to 650 GHz. The determination of the centrifugal distortion constants is significantly improved. As the molecule is close to symmetric prolate top, both reduction A and S were compared. The equilibrium structure has been derived from experimental ground state rotational constants and ab initio rovibrational interaction parameters. This semi-experimental structure is in excellent agreement with the ab initio structure calculated at the CCSD(T) level of theory using a basis set of quintuple-zeta quality and a core correlation correction. The structure of CHZPH was compared to that of CH2NH which was also determined for this goal. It is found that the semi-experimental structure of CH2NH is less accurate than the ab initio structure. It is also found that the methylene group is much more asymmetric in CH2NH than in CH2PH. 2006 Elsevier Inc. All rights reserved.