Solution Aggregation of Platinum(II) Triimine Methyl Complexes

The NMR chemical shifts of [Pt(tpy)(CH3)](PF6) (1) and [Pt(mbzimpy)(CH3)](PF6) (2), where tpy = 2,2′;6′2″-terpyridine and mbzimpy = 2,6-bis(N-methylbenzimidazol-2-yl)pyridine in room-temperature DMSO-d6 displayed concentration dependence as a result of formation of dimers. Quantification of these dimers, expressed by equilibrium constant (K), shows a greater tendency of 2 to aggregate in solution. Structural conformations of these dimers were confirmed by 2D 1H-1H NOESY; and results explicitly suggest a head-to-tail stacking arrangement of molecules in dimers.