پديدآورندگان :
Ghahremani Massomeh Department of Chemistry, University of Zanjan, Zanjan, Iran; Fax: +98 24 33052477; Tel: +98 24 33052477 , Bahrami Hamed hbahrami@znu.ac.ir Department of Chemistry, University of Zanjan, Zanjan, Iran; Fax: +98 24 33052477; Tel: +98 24 33052477 ;E-mail: , Lotfollahi Maryam Department of Chemistry, University of Zanjan, Zanjan, Iran; Fax: +98 24 33052477; Tel: +98 24 33052477 , Azimi Gohari Maryam Department of Chemistry, University of Zanjan, Zanjan, Iran; Fax: +98 24 33052477; Tel: +98 24 33052477 , Soleimani Abhari Paria Department of Chemistry, University of Zanjan, Zanjan, Iran; Fax: +98 24 33052477; Tel: +98 24 33052477
كليدواژه :
sulfinamides , proton affinity , gas phase basicity , electron affinity , ionization energy
چكيده فارسي :
Sulfinamides, R1SONR2, (also known as amino hydrogen sulfoxides), are important chiral building blocks in organic synthesis. Oxidation of sulfinamides using singlet oxygen yields sulfonamides, which have a wide variety of applications in medicinal chemistry [1]. Proton transfer reactions and ionization processes play a key role in the chemistry and biochemistry. Proton affinity (PA) and gas phase basicity (GB) determine the capability of an atom a molecule to accept a proton in the gas phase. Ionization energy (IE) is the quantity of energy that a gaseous molecule in the ground electronic state must absorb to lose its electron, resulting in a cation. Electron affinity (EA) can reflect the ability of an atom to gain electron [2]. In this study, the topical PA and GB as well as IE and EA of a set of sulfinamides including sulfinicamide, methanesulfinamide, benzenesulfinamide, trifluoromethanesulfinamide, N-methyel sulfinamide, N,N-dimethyl methanesulfinamide, 1,1,1trifluoroN-methyel methanesulfinamide, 1,1,1trifluoro N,N-dimethyl methanesulfinamide were calculated and compared using B3LYP/6-311++G(d,p) and G4MP2 methods. Sulfinamides have two suitable sites, oxygen and nitrogen atoms, to accept a proton. Hence, it was calculated two different values for the PA and GB of each molecule. The calculated PA and GB of sulfinamides for protonation of the oxygen site is higher than that of the nitrogen site in both levels of theory. In overall, the values of PA and GB at the B3LYP computational level was more than that of G4MP2. Electron donor substituents at the SO group increases PA and GPB of sulfinamides whereas electron acceptor substituents decreases PA and GPB of sulfinamides for protonation of both nitrogen and oxygen sites. The proton affinity of R1SONH2 (R1: Ph, Me, H, CF3) were calculated as, 904, 875, 853, 814 kJ/mol, respectively, for R1SONHMe (R1: Me, CF3) were 909.2 and 836 kJ/mol and for R1SONMe2 (R1: Me, CF3) were 922 and 852 kJ/mol, all values were obtaind from B3LYP method at 298 K and for protonation of oxygen site. Calculated adiabatic and vertical IEs were in the range of 8.05-10.14 eV. The results show that the VIE values are more than the AIE. As an example, the AIE of trifluoromethanesulfinamide and benzenesulfinamide calculated at the B3LYP level were 9.58 and 8.51 eV, respectively, while their VIE were 10.14 and 8.87eV, respectively. The calculated AIE of trifluoro methanesulfinamide and benzenesulfinamide at the G4MP2 level were 9.65 and 8.85 eV, respectively. In the same manner, the calculated VEA values were positive than AEA values.
