Tuning Coordination Environments Through Ligand Redox Chemistry: the Thiol - Disulfide Reaction

Oxidative coupling of 6-(pyridin-2-yl)pyridine-2(1H)-thione yields 1,2-bis(2,2′-bipyridin-6-yl)disulfide (4), which can act as a bis(chelate) to a single zinc(ii) centre. The effects on the solid-state structure of introducing a methyl substituent into each 6-position of 4 have been examined. Ligand 4 functions as a bridging ligand in [Cu2(μ-4)(μ-6)]4+ in which ligand 6 is 1,2-bis(2,2′:6′,2″-terpyridin-4′-yl)disulfide; [Cu2(μ-4)(μ-6)]4+ self-assembles from the components according to the preference shown by copper(ii) for a five-coordinate {Cu(bpy)(tpy)} environment. Reaction of 4 with [Cu(NCMe)4][PF6] leads to a product, tentatively formulated as {[Cu(4)][PF6]}n, which, in air, undergoes oxidation of both copper and ligand to yield [Cu(5)2] (H5 = 2,2′-bipyridine-6-sulfonic acid), the solid state structure of which is presented.