Functionalization of N(2) via Formal 1,3‐Haloboration of a Tungsten(0) σ‐Dinitrogen Complex

Boron tribromide and aryldihaloboranes were found to undergo 1,3‐haloboration across one W−N≡N moiety of a group 6 end‐on dinitrogen complex (i.e. trans‐[W(N(2))(2)(dppe)(2)]). The N‐borylated products consist of a reduced diazenido unit sandwiched between a W(II) center and a trivalent boron substituent (W−N=N−BXAr), and have all been fully characterized by NMR and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. Both the terminal N atom and boron center in the W−N=N−BXAr unit can be further derivatized using electrophiles and nucleophiles/Lewis bases, respectively. This mild reduction and functionalization of a weakly activated N(2) ligand with boron halides is unprecedented, and hints at the possibility of generating value‐added nitrogen compounds directly from molecular dinitrogen.