Reactions of carbon dioxide bound to aluminum diimine hydride with borane dimethyl sulfide and ammonia

Abstract

The reaction of aluminum bis-formate acenaphthene-1,2-diimine complex [(ArBIG-bian)Al(μ-OC(H)O)2Li(Thf)2] (I) (ArBIG-bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene), prepared by binding carbon dioxide by aluminum diimine hydride [(ArBIG-bian)Al(H)2]–[Li(Thf)4]+, with borane dimethyl sulfide and ammonia was studied. The reaction of I with BH3∙SMe2 (1 : 1) in toluene affords the product of hydroboration of one formate group [(ArBIG-bian)Al(μ-OC(H)O)(OB(H)OCH3)Li(Thf)]2 (II), while the reaction of I with BH3∙SMe2 (1 : 2) is accompanied by reduction of both formate groups and gives complex [(ArBIG-bian)Al(OBOCH3)2OLi2(Thf)2BH4]2 (III), methoxyboroxine (CH3OBO)3 and, presumably, compound [(ArBIG-bian)AlOCH3]. The reaction of I with one equivalent of ammonia in THF gives adduct [(ArBIG-bian)Al(NH3)(μ-OC(H)O)2Li(Thf)2] (IV), in which ammonia is coordinated to the aluminum atom, while the key bonds in I have not undergone ammonolysis. Compounds II–IV were characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction (CCDC no. 2255017 (II), 2255018 (III), 2255019 (IV)).