Bisgermylene-Stabilized Stannylone: Catalytic Reduction of Nitrous Oxide and Nitro Compounds via Element-Ligand Cooperativity
Binglin Lei, Fanshu Cao, Ming Chen, Xuyang Wang, Zhenbo Mo
Abstract
This study describes the synthesis, structural characterization, and catalytic application of a bis(germylene)-stabilized stannylone ( 2 ). The reduction of digermylated stannylene ( 1 ) with 2.2 equiv of potassium graphite (KC 8 ) leads to the formation of stannylone 2 as a green solid in 78% yield. Computational studies showed that stannylone 2 possesses a formal Sn(0) center and a delocalized 3-c-2-e π-bond in the Ge 2 Sn core, which arises from back-donation of the p-type lone pair electrons on the Sn atom to the vacant orbitals of the Ge atoms. Stannylone 2 can serve as an efficient precatalyst for the selective reduction of nitrous oxide (N 2 O) and nitroarenes (ArNO 2 ) with the formation of dinitrogen (N 2 ) and hydrazines (ArNH–NHAr), respectively. Exposure of 2 with N 2 O (1 atm) resulted in the insertion of two oxygen atoms into the Ge–Ge and Ge–Sn bonds, yielding the germyl(oxyl)stannylene ( 3 ). Moreover, the stoichiometric reaction of 2 with 1-chloro-4-nitrobenzene afforded an amido(oxyl)stannylene ( 4 ) through the complete scission of the N–O bonds of the nitroarene. Stannylenes 3 and 4 serve as catalytically active species for the catalytic reduction of nitrous oxide and nitroarenes, respectively. Mechanistic studies reveal that the cooperation of the low-valent Ge and Sn centers allows for multiple electron transfers to cleave the N–O bonds of N 2 O and ArNO 2 . This approach presents a new strategy for catalyzing the deoxygenation of N 2 O and ArNO 2 using a zerovalent tin compound.