Estimation of Solvent Effects for the Complexing Reaction of Propylene and Nickel Dithiolene

Abstract

The formation of olefin complexes is of potential importance in the separation of olefins. The solvents affect the activation energies, and hence the rates and equilibrium constants of the complexing reactions, which performance should be well estimated for the purpose of industrial practice. The solvent effects on the complexing reaction of propylene and nickel dithiolene Ni(S 2 C 2 H 2) 2 + C 2 H 4 =CH 2 → Ni(S 2 C 2 H 2) 2 ⋅C 2 H 4 =CH 2 are studied in this work, using density functional theory with B3LYP and an Onsager model. Complete optimizations of all the stagnation points are performed in benzene, toluene, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, acetone, ethanol, methanol, 1,2,3-propanetriol, dimethylsulfoxide and water, respectively. The reaction of complexing nickel dithiolene with propylene is a two-step process: the first step coordinates the propylene to S atoms in dithiolene, forming a trans-structural intermediate. The second step then yields the cis-structural product. The activation energy of the first step is higher than that of the second, indicating that the first step is the rate-determining step. The solvents make slight changes in the geometries of the reactants, transition states, intermediates and products. However, the corresponding molecular dipole moment becomes large with increase of the solvent polarity, which is beneficial to accelerate the reaction. Furthermore, the activation energies of the first (or second) step will exponentially decrease from 125.0 to 113.0 kJ⋅mol −1 (or from 101.8 to 83.43 kJ⋅mol −1) when the dielectric constants of solvents increase from 1.00 to 78.39, while the reaction rates of the first (or second) step exponentially increase from 0.7673×10-9 to 96.20×10-9 ⋅s −1

Design of nickel chelates of tetradentate N-heterocyclic carbenes with subdued cytotoxicity

“…The Becke three parameter exchange functional in conjunction with LeeYang-Parr correlation functional (B3LYP) has been employed in this study [20,21]. The LANL2DZ basis set was used for the Ni atom [22] while all other atoms are treated with 6-31G(d) basis set [23]. All stationary points are characterized as minima by evaluating Hessian indices on the respective potential energy surfaces.…”