Catalytic Reduction of N₂ to Borylamine at a Molybdenum Complex

Abstract

Catalytic formation of borylamines from atmospheric N 2 is achieved for the first time using a series of homogenous (triphosphine)Mo complexes. Stepwise functionalization of the (triphosphine)Mo-nitrido complex with chloroborane led to the synthesis of the imido complex. Electrochemical characterization of the (PPP)Mo-nitrido and (PPP)Mo-borylimido complexes showed that the latter is much more easily reduced.Scheme 1. Approaches to N 2 functionalization by boron derivatives: stoichiometric and catalytic NÀB bond formation.

Boron Insertion into the N≡N Bond of a Tungsten Dinitrogen Complex

“…Since the synthesis of the first stable terminal dinitrogen complex, [Ru­(NH 3 ) 5 N 2 ] 2+ , by Allen and Senoff nearly 60 years ago, a wide variety of transition-metal complexes with N 2 ligands in various coordination modes have been reported, − some capable of spontaneously splitting the NN triple bond to form nitride complexes . Many of these complexes have been used as versatile platforms for the direct stoichiometric formation of N–C, N–Si, N–B, N–Al, and N–P bonds from N 2 , with or without splitting the dinitrogen N–N bond. − Furthermore, several systems have been successfully employed for the catalytic synthesis of tertiary and secondary silylamines − and, most recently, tertiary borylamines from N 2 under highly reducing conditions.…”

“…14 Many of these complexes have been used as versatile platforms for the direct stoichiometric formation of N−C, N−Si, N−B, N−Al, and N−P bonds from N 2 , with or without splitting the dinitrogen N−N bond. 15−20 Furthermore, several systems have been successfully employed for the catalytic synthesis of tertiary and secondary silylamines 21−25 and, most recently, tertiary borylamines 26 from N 2 under highly reducing conditions.…”

Molecular Electrochemical Reductive Splitting of Dinitrogen with a Molybdenum Complex**

“…Transition metal complexes based on Mo [6][7][8][9][10][11][12] and Fe, [13][14][15][16] mainly, but also Re, [17][18][19] V, [20] Cr, [21][22][23] Co [24,25] and Ti [26] have been investigated in this purpose. However, a major hurdle toward such chemistry lies in the kinetically favorable proton reduction into H 2 .…”