Phosphinoboration of diazobenzene with Ph2PBR'2 cleanly affords products of the form Ph2P(PhNNPh)(BR'2) (R'2 = cat 2, quin 4) and shows evidence of Ph2P(PhNNPh)(Bpin) 7 formation. The mechanism of these reactions was probed computationally and shown to proceed via intermediates involving a diazobenzene-adduct of the boron center of the PB reagent. The resulting PNNB species 2 and 4 are shown to be FLPs. Despite the presence of weakly Lewis acidic boron centers, these species react with diazobenzene. Further, the FLP reactivity of 2 was further probed with 4-phenyl-1,2,4-triazole-3,5-dione, 1,10-phenanthroline-5,6-dione, and benzyl azide to give unique five-, six-, and eight-membered heterocyclic rings. Thus, phosphinoboration provides a new avenue to FLPs in which donor and acceptor sites are linked by nitrogen atoms.