Diphosphino‐Functionalized 1,8‐Naphthyridines: a Multifaceted Ligand Platform for Boranes and Diboranes

A 1,8‐naphthyridine diphosphine (NDP) reacts with boron‐containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B(2)Br(4), NDP underwent self‐deprotonation to afford [NDP‐B(2)Br(3)]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr(3) and NDP in a non‐polar solvent provided the simple phosphine‐borane adduct [NDP(BBr(3))(2)], which then underwent intramolecular halide abstraction to furnish the salt [NDP‐BBr(2)][BBr(4)], featuring a different coordination mode from that of [NDP‐B(2)Br(3)]Br. Direct deprotonation of NDP by KHMDS or PhCH(2)K generates mono‐ and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B(2)(NMe(2))(2)Cl(2) to afford NDP‐based diboranes with three or four amino substituents.