A Series Of Primary Alkylamine Borane Adducts Cxh2x+1nh2bh3: Synthesis And Properties

Primary alkylamine borane adducts CxH2x+1NH2BH3 (CxAB) are unconventional molecules that may offer great opportunities in chemistry owing to their dihydrogen H delta+...H delta- bonds. Herein, we focus on six CxAB (x=4, 6, 8, 10, 12, 14), synthesized by Lewis acid-base reaction between the complex (CH3)(2)S.BH3 and the primary alkylamines. At ambient temperature, C4AB and C6AB are oily liquid, and the other adducts are crystalline solids. The melting temperatures of the CxAB linearly increase as a function of ln(x) due to stronger intermolecular Van der Waals forces between the alkyl chains, and they are higher by 20-40 degrees C than those of the amines due to dihydrogen H delta+...H delta- bonds between the NH2BH3 heads. The occurrence of dihydrogen H delta+...H delta- bonds is further confirmed by molecular and structural analyses. This is discussed hereafter.