Effects of N₂Binding Mode on Iron-Based Functionalization of Dinitrogen to Form an Iron(III) Hydrazido Complex

Abstract

Distinguishing the reactivity differences between N complexes having different binding modes is crucial for the design of effective N-functionalizing reactions. Here, we compare the reactions of a K-bridged, dinuclear FeNNFe complex with a monomeric Fe(N) complex where the bimetallic core is broken up by the addition of chelating agents. The new anionic iron(0) dinitrogen complex has enhanced electron density at the distal N atoms of coordinated N, and though the N is not as weakened in this monomeric compound, it is much more reactive toward silylation by (CH)SiI (TMSI). Double silylation of N gives a three-coordinate iron(III) hydrazido(2-) complex, which is finely balanced between coexisting S = 1/2 and S = 3/2 states that are characterized by crystallography, spectroscopy, and computations. These results give insight into the interdependence between binding modes, alkali dependence, reactivity, and magnetic properties within an iron system that functionalizes N.

Tetralithio Metalla‐aromatics with Two Independent Perpendicular Dilithio Aromatic Rings Spiro‐fused by One Manganese Atom

“…TheL UMO is a p*-orbital, and is bonding and antibonding in nature with respect to the central CÀCs ingle bond and the two terminal C=Cd ouble bonds,r espectively.T he analogous HOMO and LUMO are found for diimine,awell-known non-innocent ligand. [11] Hence,d ilithio reagents can exhibit different valence states (A, B and C)i nt ransition metal complexes (Scheme 3), which has also been demonstrated in our previous work. [4,12] Upon reduction the central CÀCb ond get shortened, whereas the two terminal CÀCbonds become elongated.…”

Isolation and characterization of a high-spin mixed-valent iron dinitrogen complex

“…Filtration of this solution through Celite® and vapor diffusion of pentane into the filtrate at −40 °C led to the formation of green crystals of the iron(I)iron(0) dinitrogen complex salt [K(18-c-6)(THF) 2 ][L Me Fe(μ-N 2 )FeL Me ] ( 2 ) in 63% yield. 7 X-ray crystallography of 2 revealed a structure with an N–N distance of 1.186(6) Å, which is significantly longer than that in free N 2 (1.09 Å), suggestive of substantial dinitrogen activation (see Figures 1 and 3). A comparison of the core bond distances and angles for 2 to those of the known analogues 1 , [K(18-c-6)(12-c-4)] 2 [L Me Fe(μ-N 2 )FeL Me ] ( 3 ) and K 2 [L Me Fe(μ-N 2 )FeL Me ] ( 4 ) (shown in Figure 2) reveals that the metrical parameters for all four complexes are statistically indistinguishable (Table 1).…”

“…A comparison of the core bond distances and angles for 2 to those of the known analogues 1 , [K(18-c-6)(12-c-4)] 2 [L Me Fe(μ-N 2 )FeL Me ] ( 3 ) and K 2 [L Me Fe(μ-N 2 )FeL Me ] ( 4 ) (shown in Figure 2) reveals that the metrical parameters for all four complexes are statistically indistinguishable (Table 1). 7…”

Low-coordinate first-row transition metal complexes in catalysis and small molecule activation

“…[91][92][93][94][95] Treatment of the reduced iron species 29b with 18-crown-6 affords a new four-coordinate complex 30, in which potassium is coordinated by an N 2 ligand. 97 This species is active towards silylation, reacting with Me 3 SiI to afford the three-coordinate Fe(III) hydrazido species 31 along with Fe(II) iodide 32. 97 It should be noted that reacting 29b with Me 3 SiI directly affords 31 in low yields (ca.…”

“…97 This species is active towards silylation, reacting with Me 3 SiI to afford the three-coordinate Fe(III) hydrazido species 31 along with Fe(II) iodide 32. 97 It should be noted that reacting 29b with Me 3 SiI directly affords 31 in low yields (ca. 5%) with long reaction times.…”