Transition metal dinitrogen complexes supported by a versatile monoanionic [N2P2] ligand

Abstract

By adjusting to the steric and electronic requirements of differing metal centers, the new multidentate monoanionic ligand [N(2)P(2)] has demonstrated a unique ability to stabilize a range of transition metal-dinitrogen complexes in a variety of oxidation states and coordination geometries.

Metal–dioxygen and metal–dinitrogen complexes: where are the electrons?

“…vi One of the first μ−η 2 :η 2 -N 2 4− complexes was a dizirconium complex of a chelating PNP ligand, viia and others have been identified with other strongly donating ligands and early transition metals. vii,viii,x,xi In these complexes, the N-N distance varies significantly, from 1.38 Å to 1.63 Å. In the μ−η 2 :η 2 -N 2 4− complexes, the N 2 cannot be displaced because the significant reduction makes it very strongly bound.…”

“…vi Most examples of μ-η 2 :η 2 -N 2 binding come from complexes of early (group 5 and lower) transition metals and lanthanides. vii,viii,ix,x,xi (The structurally characterized exceptions are a recent dichromium complex, xii and an unusual nickel-sodium-lithium cluster. xiii,xiv ) In both O 2 and N 2 complexes, the preference for end-on vs. side-on bridging is determined by several factors, including the availability of metal d orbitals viic and steric hindrance from the spectator ligands.…”

“…xb A N 2 P 2 ligand has been used to create N 2 complexes of Ti, Mn, and Fe, showing that the more electronegative metals give less N-N bond weakening. viii Likewise, comparison of β-diketiminate complexes of Fe, Co, and Ni show that the metals further to the right of the periodic table give less N-N weakening. xxiiib …”

Terminal Iron Dinitrogen and Iron Imide Complexes Supported by a Tris(phosphino)borane Ligand

“…The pseudotetrahedral geometry has been successfully used to stabilize terminal imide [5, 6 ] and nitride [7, 8] ligands because the π-antibonding d-orbitals of e parentage are usually empty, but most of the N 2 complexes in this geometry are dinuclear, bridged species rather than terminal ones due to the difficulty of implementing sufficient steric protection. [9, 10] On the other hand, the trigonal-bipyramidal geometry enforced by tetradentate tris(phosphino)silyl ligands has been shown to stabilize terminal N 2 complexes of iron in three different oxidation states, [11] but is less well suited for accomodating Fe–N multiple bonds because of the presence of low-lying, π-antibonding orbitals. [12] …”

Syntheses and Crystal Structures of Novel Functionalized Lithium Silylamides R(4–n)Si(N(Li)CH2CH2NR'2)n (R = Me, Ph, R' = Me, iPr; n = 2, 3)

“…Novel applications for instance comprise silylamides as supporting ligands for complexes with metal-metal single and multiple bonds. [3,4] Moreover, the use of functionalized silylamide ligands bearing additional donor groups has opened new perspectives in coordination chemistry in particular concerning the stabilization of transition metal dinitrogen complexes [5] and lanthanoid metal alkyl complexes. [6] 2-with X = NMe 2 or OMe.…”