Quantum Chemical Study of the Reaction between Ni⁺ and H₂S

Abstract

The reaction between the Ni(+) cation and H(2)S is studied by considering both the doublet ground state and the lowest-lying quartet state. For the doublet state the reaction is endothermic, whereas it is exothermic for the quartet state. Both CCSD(T)//B3LYP and B3LYP levels of theory, combined with the triple-zeta quality TZVP++G(3df,2p), predict that there are three spin crossings along the characterized reaction path. The first one is located after the first transition state, and the second and third ones before and after the second transition state. On the quartet potential energy surface, both transition states are close in energy to the reactants, while on the doublet surface both lie quite higher in energy. The doublet and quartet states of the HNiSH(+) four-membered intermediate lie very close in energy and their corresponding electronic configurations are connected by a single electron flip. This suggests that the -SH ligand would not prevent a facile intersystem crossing at this intermediate molecule, in contrast to the larger protection provided by the more electronegative -OH ligand.

Quantum Chemical Study of the Reactions between Pd+/Pt+ and H2O/H2S

“…It is observed that only the doublet state of HPdOH + has a T1-diagnostic value larger than the recommended threshold, and that its quartet state lies on the mark. We have recalculated both states with a multiconfigurational CASSCF-A C H T U N G T R E N N U N G (17,12) wave function. Notice that the selected active space contains all the valence electrons and all the valence orbitals resulting from the atomic configurations of the Pd 4d 9,8 5 s 0,1 , O 2s 2 2p 4 and H 1 s 1 .…”

“…Therefore, the quartet spin state can be long‐lived enough to undergo reactions with CH 4 and also with the O 2 molecule 30. On the other hand, the doublet spin state undergoes rapid rearrangement to the nonreactive C 2 v symmetric Ni + ⋅⋅⋅ OH 2 complex, as demonstrated by using simple quantum molecular dynamics calculations 12…”

“…The study of the reactivity of bare transition-metal cations in the gas phase is of utmost importance given the role they play in a variety of chemical processes, including the crucial and challenging s-activation process. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Among these studies, the reactions between transitionmetal cations and water have been extensively studied from the pioneering state-specific studies of Armentrout et al, who laid out most of the main issues, [17][18][19] to the recent measurements by Bohme et al, who have compiled their results in a recent report. [20] Additionally, quantum chemistry mechanistic studies performed for the early, [21][22][23] middle, [24,25] and late [26] first-row transition metals agreed with the experimental evidence, [20] which showed that whereas for early first-row transition metals their bare cations are more reactive than their oxides, the opposite is the case for the late transition-metal cations.…”

“…[30] On the other hand, the doublet spin state undergoes rapid rearrangement to the nonreactive C 2v symmetric Ni + ···OH 2 complex, as demonstrated by using simple quantum molecular dynamics calculations. [12] In related previous work, [12] we studied the reaction between Ni + and H 2 S to understand the influence of changing the oxygen to sulfur. As in the case of HNiOH + , whereas in the doublet state there is a negligible barrier associated with the HNiSH + /NiSH 2 + isomerization, in the quartet state, this…”

“…CCSD(T)//B3LYP, B3LYP, and PBE0A C H T U N G T R E N N U N G (ZORA) relative energies [eV] for the quartet state M + (D 1 ), M···XH 2 + (D 2 ) and HMXH + (D 3 ) relative to their doublet ground state, and that of the doublet MX + relative to its quartet ground state (D 4 ). [67] 1.08 [12] CCSD(T)//B3LYP 1.69 À0.01 [67] 3.…”