Controlled Expansion of a Strong‐Field Iron Nitride Cluster: Multi‐Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity

Abstract

Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the μ -nitrido cluster [Fe (μ -N)(CO) ] , this analogy is limited owing to the electron-withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe (μ -N)(CO) (CNAr ) ] , an electron-rich analogue of [Fe (μ -N)(CO) ] , where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main-group and transition-metal centers to yield unsaturated sites. The resulting clusters display surface-like reactivity through coordination-sphere-dependent atom rearrangement and metal-metal cooperativity.

Quantification of the Electrostatic Effect on Redox Potential by Positive Charges in a Catalyst Microenvironment

“…This distribution pattern of phosphine ligands likely reduces steric interactions, and a similar situation was observed with mterphenylisocyanide-substituted 1 − . 44 In agreement with the hypothesis that steric effects are important, Fe−P bond lengths in 11 3+ at 2.170(2), 2.211(2), 2.158(2), and 2.187(2) Å are elongated compared with those in 9 + , which are 2.1553(13) and 2.1516(17) Å, respectively.…”

Reactions of [Fe6C(CO)14(S)]2–: Cluster Growth, Redox, Sulfiding

“…Iron carbonyl clusters are characteristically susceptible to ligand substitution. [9] In the case of Fe-S-CO clusters such reactions often proceed by associative mechanisms. [10] The reaction with 5 equiv.…”

Controlled Expansion of a Strong‐Field Iron Nitride Cluster: Multi‐Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity

“…These data indicate that the increased donor strength of the CNAr Mes2 ligands creates as ufficiently electron-rich cluster as to discourage reduction events,w hile also allowing for the stabilization of electron-deficient cluster species.I ndeed, as suggested by the reversibility of the À0.65 Vevent, chemical oxidation of Na [1]with trityl chloride (ClCPh 3 )leads cleanly to the neutral, paramagnetic cluster Fe 4 N(CO) 8 (CNAr Mes2 ) 4 (1), as determined by X-ray diffraction (Scheme 1a nd Figure S4.3). [32] Angewandte Chemie Zuschriften Them ost unique feature of [1] À relative to [Fe 4 (m 4 -N)(CO) 12 ] À is that its increased electron-rich character allows for nucleophilic reactivity of the interstitial nitride towards avariety of electrophilic substrates.For example,treatment of Na [1]w ith thallium triflate (TlOTf;O Tf = [O 3 SCF 3 ] À )p roduces the adduct Fe 4 (Tl-(m 4 -N))(CO) 8 (CNAr Mes2 ) 4 (2; Scheme 2a nd Figure 1). [32] Angewandte Chemie Zuschriften Them ost unique feature of [1] À relative to [Fe 4 (m 4 -N)(CO) 12 ] À is that its increased electron-rich character allows for nucleophilic reactivity of the interstitial nitride towards avariety of electrophilic substrates.For example,treatment of Na [1]w ith thallium triflate (TlOTf;O Tf = [O 3 SCF 3 ] À )p roduces the adduct Fe 4 (Tl-(m 4 -N))(CO) 8 (CNAr Mes2 ) 4 (2; Scheme 2a nd Figure 1).…”

“…with the m-terphenyl periphery in wireframe.S ome mesityl groups have been omitted for clarity. [32] Angewandte Chemie Zuschriften Them ost unique feature of [1] À relative to [Fe 4 (m 4 -N)(CO) 12 ] À is that its increased electron-rich character allows for nucleophilic reactivity of the interstitial nitride towards avariety of electrophilic substrates.For example,treatment of Na [1]w ith thallium triflate (TlOTf;O Tf = [O 3 SCF 3 ] À )p roduces the adduct Fe 4 (Tl-(m 4 -N))(CO) 8 (CNAr Mes2 ) 4 (2; Scheme 2a nd Figure 1). In contrast, [Fe(m 4 -N)(CO) 12 ] À does not react with TlOTf even after the addition of multiple equivalents and several hours of heating in THF at 60 8 8C.…”

“…Molecular structures of the Fe 5 clusters 5 and 6 with the m-terphenyl periphery in wireframe.S ome mesityl groups have been omitted for clarity. [32] Angewandte Chemie Zuschriften…”