Study of silyl cations bearing an aryldiamine pincer ligand

In this paper, we describe two routes to prepare silyl cations with at least one Si-H bond by using the bis-chelating ligand C6H3(CH(2)NMe(2))(2)-2,6. The first is the reaction between a pentacoordinate dihydrosilane ArRSiH(2) [Ar = (C6H3(CH(2)NMe(2))(2)-2,6] and an electrophile. The second is the reaction of the lithium derivative ArLi with a dichlorohydrosilane RSiHCl(2). These cations are 5-coordinated owing to intramolecular chelation by the two NMe(2) groups. By using the same bis-chelating ligand, the formation of silyl cations with Si-C bonds has also been investigated. We show that in an aprotic solvent with non-nucleophilic counteranions [(3,5-(CF3)(2)C6H3]B-4(-), BPh(4)(-)] there is also his chelation of the two amino groups to the silicon atom giving 5-coordinated silyl cations while in the presence of nucleophilic anions (Cl-, Br-, I-, CF3SO3-) there is no his chelation of the two NMe(2) groups but rather a fluxional coordination of these groups occurring at silicon.