Reduction of Nitrous Oxide by Light Alcohols Catalysed by a Low-Valent Ruthenium Diazadiene Complex

Decomposition of the environmentally harmful gas nitrous oxide (N₂ O) is usually performed thermally or catalytically. Selective catalytic reduction (SCR) is currently the most promising technology for N₂ O mitigation, a multicomponent heterogeneous catalytic system that employs reducing agents such as ammonia, hydrogen, hydrocarbons, or a combination thereof. This study reports the first homogenous catalyst that performs the reduction of nitrous oxide employing readily available and cheap light alcohols such as methanol, ethanol or ethylene glycol derivatives. During the reaction, these alcohols are transformed in a dehydrogenative coupling reaction to carboxylate derivatives, while N₂ O is converted to N₂ and H₂ O, later entering the reaction as substrate. The reaction is catalysed by the low-valent dinuclear ruthenium complex [Ru₂ H(μ-H)(Me₂ dad)(dbcot)₂ ] that carries a diazabutadiene, Me₂ dad, and two rigid dienes, dbcot, as ligands. The reduction of nitrous oxide proceeds with low catalyst loadings under relatively mild conditions (65-80 °C, 1.4 bar N₂ O) achieving turnover numbers of up to 480 and turnover frequencies of up to 56 h^-1 .