Primary alkylamine borane adducts C x H 2x + 1 NH 2 BH 3 (CxAB) are unconventional molecules that may offer great opportunities in chemistry owing to their dihydrogen H δ + ⋅⋅⋅H δÀ bonds. Herein, we focus on six CxAB (x = 4,6,8,10,12,14), synthesized by Lewis acid-base reaction between the complex (CH 3 ) 2 S⋅BH 3 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°C than those of the amines due to dihydrogen H δ + ⋅⋅⋅H δÀ bonds between the NH 2 BH 3 heads. The occurrence of dihydrogen H δ + ⋅⋅⋅H δÀ bonds is further confirmed by molecular and structural analyses. This is discussed hereafter.