Diruthenium complex catalyzed reduction of nitroarenes-investigation of reaction pathway

Abstract A diruthenium complex, [( L )Ru 2 (η 6 -C 6 H 6 ) 2 Cl 2 ](PF 6 ) 2 ( 1 ) ( L = 5-phenyl-2,8-di-2-pyridinylanthyridine), was prepared and characterized. This diruthenium complex 1 was found to be an efficient catalyst for the reduction of aromatic nitro compounds leading to the corresponding aniline derivatives with the use of hydrazine as the reducing agent at 80 °C in an ethanol solution. Catalytic activity of 1 towards various possible intermediates leading to anilines was investigated to understand the reaction pathway. These studies indicate that this reduction proceeds via a direct route as evidenced by hydroxylamines being observed as the major intermediate followed by the appearance of aniline under the catalytic conditions. Thus, the reaction pathway of this catalytic system is discussed.