TY - JOUR
T1 - Ion-transport catalysis
T2 - Catalyzed isomerizations of NNH+ and NNCH3+
AU - Chalk, Andrew J.
AU - Radom, Leo
PY - 1999/2/24
Y1 - 1999/2/24
N2 - High-level ab initio calculations using the G2(**) and G2(ZPE=MP2) methods have been employed to examine the effect of interaction with a range of neutral molecules (X) on the barrier to the degenerate proton-transport reactions in NNH+ (X = Ar, HF, CO, N2, H2O) and methyl cation-transport reactions in NNCH3+ (X = HF, H2, N2, HCl, H2O). It is found that the barriers to both proton and methyl cation transport are lowered from their values in the isolated ions of 182 and 152 kJ mol-1, respectively, by interaction with species having values of the proton or methyl cation affinity, respectively, lower than that of molecular nitrogen. Interaction with species that have larger values of proton or methyl cation affinities leads to a further lowering of the barrier, but transfer to the neutral molecule X becomes the more energetically favorable process in such cases. It is found that the ideal catalyst for ion transport should have an ion affinity close to but less than that of molecular nitrogen and have a large dipole moment.
AB - High-level ab initio calculations using the G2(**) and G2(ZPE=MP2) methods have been employed to examine the effect of interaction with a range of neutral molecules (X) on the barrier to the degenerate proton-transport reactions in NNH+ (X = Ar, HF, CO, N2, H2O) and methyl cation-transport reactions in NNCH3+ (X = HF, H2, N2, HCl, H2O). It is found that the barriers to both proton and methyl cation transport are lowered from their values in the isolated ions of 182 and 152 kJ mol-1, respectively, by interaction with species having values of the proton or methyl cation affinity, respectively, lower than that of molecular nitrogen. Interaction with species that have larger values of proton or methyl cation affinities leads to a further lowering of the barrier, but transfer to the neutral molecule X becomes the more energetically favorable process in such cases. It is found that the ideal catalyst for ion transport should have an ion affinity close to but less than that of molecular nitrogen and have a large dipole moment.
UR - http://www.scopus.com/inward/record.url?scp=0033599336&partnerID=8YFLogxK
U2 - 10.1021/ja982928l
DO - 10.1021/ja982928l
M3 - Article
SN - 0002-7863
VL - 121
SP - 1574
EP - 1581
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 7
ER -