Alkane elimination reaction of phosphinimino-amine ligand HL (L = (2,6-Pr-i(2)-C6H3)NC(Me)CHP(Cy-2) N(2,6-Me-2-C6H3)) with (MgBu2)-Bu-n and Sc(CH2SiMe3)(3)(THF)(2), respectively, can afford the corresponding phosphinimino-amine supported magnesium monoalkyl complex (LMgBu)-Bu-n(THF) (1) and scandium dialkyl complex LSc(CH2SiMe3)(2) (2). 2 can initiate the polymerization of ethylene efficiently under the activation of [Ph3C][B(C6F5)(4)]. Magnesium hydride complex [LMgH](2) (3) can be easily obtained by the reaction of 1 and phenylsilane. The hydride species in 3 can conduct the dearomatisation of pyridine to give dearomatisation product 1,2-dihydropyridide (4). (C) 2015 Elsevier B.V. All rights reserved.