RT journal article
T1 Spin-Crossing in the (Z)‑Selective Alkyne Semihydrogenation Mechanism Catalyzed by Mo3S4 Clusters: A Density Functional Theory Exploration
A1 Gutiérrez Blanco, María
A1 García Algarra, Andrés
A1 Guillamón, Eva
A1 Fernández-Trujillo Rey, María Jesús
A1 Oliva, Mónica
A1 García Basallote, Manuel
A1 Llusar, Rosa
A1 S. Safont, Vicent
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
AB Semihydrogenation of internal alkynes catalyzed by the air-stable imidazolyl amino [Mo3S4Cl3(ImNH2)3]+ cluster selectively affords the (Z)-alkene under soft conditions in excellent yields. Experimental results suggest a sulfur-based mechanism with the formation of a dithiolene adduct through interaction of the alkyne with the bridging sulfur atoms. However, computational studies indicate that this mechanism is unable to explain the experimental outcome: mild reaction conditions, excellent selectivity toward the (Z)-isomer, and complete deuteration of the vinylic positions in the presence of CD3OD and CH3OD. An alternative mechanism that explains the experimental results is proposed. The reaction begins with the hydrogenation of two of the Mo3(μ3-S)(μ-S)3 bridging sulfurs to yield a bis(hydrosulfide) intermediate that performs two sequential hydrogen atom transfers (HAT) from the S-H groups to the alkyne. The first HAT occurs with a spin change from singlet to triplet. After the second HAT, the singlet state is recovered. Although the dithiolene adduct is more stable than the hydrosulfide species, the large energy required for the subsequent H2 addition makes the system evolve via the second alternative pathway to selectively render the (Z)-alkene with a lower overall activation barrier.
PB AMER CHEMICAL SOC
SN 1520-510X
YR 2024
FD 2024
LK http://hdl.handle.net/10498/31135
UL http://hdl.handle.net/10498/31135
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 11-nov-2026