title: Selective palladation of a large (32 ring atom) macrocyclic ligand at a bis(N-heterocyclic carbene) coordination pocket through transmetallation of the corresponding mercury(II) derivative.
abstract: Treatment of N(2),N(6)-bis(6-acrylamidopyridin-2-yl)pyridine-2,6-dicarboxamide with benzimidazole gives the acyclic aza-Michael addition product N(2),N(6)-bis(6-(3-(1H-benzo[d]imidazol-1-yl)propanamido)pyridin-2-yl)pyridine-2,6-dicarboxamide (2). The macrocycle N(1),N(7)-pyridine-2,6-dimethyl-N(2),N(6)-bis(6-(3-(1H-benzo[d]imidazol-1-yl)propanamido)pyridin-2-yl)pyridine-2,6-dicarboxamide dibromide ([H(2)L(2)]Br(2)) is formed through the double alkylation of 2 with 2,6-bis(bromomethyl)pyridine. The imidazole analogues of 2 and [H(2)L(2)]Br(2) (1 and [H(2)L(1)]Br(2), respectively) have also been prepared. Mercuration of the two benzimidazolium groups in [H(2)L(2)]Br(2) with mercury(II) acetate in the presence of [N(CH(3))(4)](2)[HgBr(4)] proceeds to give [HgL(2)][HgBr(4)] in good yield. The ability of [HgL(2)][HgBr(4)] to readily partake in transmetallation reactions is demonstrated by the reaction that occurs with PdCl(2)(COD) to form [PdClL(2)][PF(6)]. The structures of 2, [HgL(2)][HgBr(4)] and [PdClL(2)][PF(6)] have been determined.
authors.affiliation: School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: Kim
authors.initials: K
authors.lastname: Meyer
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Dalebrook
authors.forename: L James
authors.initials: LJ
authors.lastname: Wright