Proton transfer of NH3-HCl catalyzed by only one molecule.
The proton transfer in NH(3)-HCl by only one molecule of catalyst was studied by using the MP2 method with the large 6-311++G(2d,2p) basis set. The 18 structures are obtained for the smallest units, NH(3)-HCl-A trimers, for which the proton transfer maybe occurred. The final results show that the proton transfers have occurred in the 15 cyclic shape structures for A = H(2)SO(4), H(2)SO(3), HCOOH (a), HF, H(2)O(2), HNO(3), HNO(2) (a), CH(3)OH, HCl, HNC, H(2)O, HNO(2) (b), NH(3), HCOOH (b), and HCHO, and not occurred in another 3 trimer structures for A = HCN, H(2)S, and PH(3). These results show that the proton transfer occurs from HCl to NH(3) when catalyst molecule A (acidic, neutral, or basic) not only as a proton donor strongly donates the proton to the Cl atom but as an acceptor strongly accepts the proton from the NH(3) molecule in the cyclic H-bond structure. In this work, a proton circumfluence model is proposed to explain the mechanism of the proton transfer. We find that, for the trimer, when the sum of two hydrogen bond lengths (R = R(1) + R(2)) is shorter than 5.0 A, molecule A has the ability to catalyze the proton transfer. In addition, we also find that the interaction energy E(int) between NH(3)-HCl and A is nearly related to the extent (R(H1)(-)(Cl)) of proton transfer, that is, the interaction energy E(int) increases with the proton transfer.
Li
Ru-Jiao
RJ
State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P.R. China.
Li
Zhi-Ru
ZR
Wu
Di
D
Chen
Wei
W
Li
Ying
Y
Wang
Bing-Qiang
BQ
Sun
Chia-Chung
CC
D000641:Ammonia / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D006851:Hydrochloric Acid / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011522:Protons; D014732:Vibration
D011522:Protons; D000641:Ammonia; D006851:Hydrochloric Acid