Non‐Spectator Feature of α‐Diimine Mimicked Di/tetrahydro‐bisisoquinoline and Biimidazopyridine on {Ru(acac)2} Platform

Abstract

The diverse reactivity profiles of α‐diimine analogues, di/tetrahydro‐bisisoquiniline (L1–2H/L2–4H), and biimidazopyridine (L3) have been illustrated on the {Ru(acac)2} platform (acac=acetylacetonate). Increasing Lewis acidity on coordination to {Ru(acac)2} as well as fine tuning of ligand backbone led to oxidative dehydrogenation of L1–2H/L2–4H to yield metallated bisisoquinoline (BIQ) and unexplored C–C coupling/nucleophilic attack assisted ring opening reactions at L3 to rearrange into modified metallated amidate functions. Preformed L1–4H involving amine functionality underwent in situ transformation to imine in [RuII/III(acac)2(L1–2H)]n+ (1n+, n = 0,1), followed by dehydrogenation to yield [RuII/III(acac)2(BIQ)]n+ (2n+, n = 0,1). Analogous complex [RuII(acac)2(L2–4H)]n+ (3n+, n = 0,1) encompassing diimine (L2–4H) ligand also participated in similar dehydrogenation process to generate 2n+. On the other hand, reaction of L3 with {Ru(acac)2} led to the simultaneous formation of three products: [RuIII(acac)2(L3)]ClO4 ([4]ClO4) incorporating unperturbed N,N‐donating L3 and [RuIII(acac)(L4)] (5)/[RuIII(acac)2(L5)] (6) with functionalized L3. Involvement of intramolecular C–C coupling between the methine carbon of acac and L3 or the intermolecular nucleophilic attack of H2O at L3, resulted in functionalized L4 or L5 in 5 or 6, respectively. Authentication of the isolated products was made via structural, electrochemical and spectral details along with theoretical support.