Synthesis and Ligand Modification Chemistry of a Molybdenum Dinitrogen Complex: Redox and Chemical Activity of a Bis(imino)pyridine Ligand

Abstract

The bis(imino)pyridine 2,6-(2,6-iPr2-C6H3N=CPh)2-C5H3N ((iPr)BPDI) molybdenum dinitrogen complex, [{((iPr)BPDI)Mo(N2)}2(μ2,η(1),η(1)-N2)] has been prepared and contains both weakly (terminal) and modestly (bridging) activated N2 ligands. Addition of ammonia resulted in sequential N-H bond activations, thus forming bridging parent imido (μ-NH) ligands with concomitant reduction of one of the imines of the supporting chelate. Using primary and secondary amines, model intermediates have been isolated that highlight the role of metal-ligand cooperativity in NH3 oxidation.

Conversion of Carbon Dioxide to Methanol Using a C–H Activated Bis(imino)pyridine Molybdenum Hydroboration Catalyst

“…34 The C(2)−C(3) and C(7)−C(8) distances determined for 3 of 1.442(17) and 1.401(18) Å, respectively, are also significantly contracted from the C imine −C pyridine bond lengths found for unreduced chelates (1.50 Å). 34 Comparable C imine −C pyridine distances reported for [( iPr2Ar BPDI)Mo(N 2 )] 2 (μ 2 ,η 1 ,η 1 -N 2 ) of 1.421(5) and 1.437(5) Å have recently been assigned to twoelectron reduction of the chelate; 35 however, this complex features a geometry in which Mo does not lie in the idealized PDI chelate plane. As previously described, d-orbital radial expansion enhances second-row metal backbonding such that redox noninnocent ligand LUMOs are greatly destabilized, rendering their population unlikely.…”

Stepwise N–H bond formation from N2-derived iron nitride, imide and amide intermediates to ammonia

“…In that system, the proposed Ir–NH intermediate is thought to undergo rapid disproportionation to Ir nitride and amide species. Conversely, a bimetallic Mo system was shown to react with ammonia to form a stable dimolybdenum bis(μ-imide) complex,39 highlighting the increased stability of bridging imido ligands versus terminal ones.…”

Reactivity and Properties of Metal Complexes Enabled by Flexible and Redox-Active Ligands with a Ferrocene Backbone

“…[13][14][15][16][17][18][19][20][21] In addition, Chirik and coworkers exploited the potential of base metals in catalytic transformations by using flexible and redox non-innocent ligands to overcome the limitation of first row transition metals that usually undergo single electron processes (Chart 1d). [22][23][24][25] Besides traditional phosphine and nitrogen donors, an arene is suitable for metal-ligand cooperation as well: first, the coordination mode of the arene can vary from  6 to  2 according to the degree of delocalization. 26,27 Second, while the HOMO of an arene can act as a  or  donor, its LUMO has the appropriate symmetry and energy to engage in back-donation with electron-rich metals.…”