[Fe(CNXyl)₄]²⁻: An Isolable and Structurally Characterized Homoleptic Isocyanidemetalate Dianion

Abstract

World's record: The first isolation and structural characterization of a homoleptic isocyanidemetalate dianion has been achieved with [Fe(CNXyl)4]2− (Xyl=2,6‐dimethylphenyl; see structure, Fe red, N blue, C gray). Spectral and structural data indicate that metal‐to‐isocyanide back‐bonding in this electron‐rich species is the largest ever observed in a homoleptic isocyanide complex containing only terminally bound ligands.

Synthesis and characterization of titanium tetraisocyanide complexes, [CpTi(CNXyl)4E], E=I, SnPh3, and SnMe3

“…Prominent shoulders observed in the IR m(CN) spectral region for 3 and 4, but not 1, suggests that the bulky character of the R 3 Sn groups in the former two complexes, also contributes to further reduction in the local symmetry of the titanium. A similar bifurcation of the IR m(CN) band envelope in THF solution was recently reported for trans-[Fe(CNXyl) 4 (SnPh 3 ) 2 ], which contains a Fe(CN) 4 Sn 2 core structure of nearly D 4h symmetry in the solid state [26]. 1 H and 13 C NMR spectra of diamagnetic 1, 3, and 4 are summarized in Section 2 under the respective compounds and show normal resonances and positions for the Cp and aliphatic/aromatic portions of the coordinated CNXyl ligands.…”

Terminal Iron Carbyne Complexes Derived from Arrested CO2 Reductive Disproportionation

“…Despite the electronic structure features outlined above indicating that Na[ 3 ] should display metal‐centered nucleophilic reactivity, this complex possesses several other Lewis basic sites that may interfere with such reactivity. While we are currently searching for conditions where electrophiles can cleanly add to the Fe center, it is notable that monoanions of the type [HFeL 4 ] − , to which carbamate–carbyne Na[ 3 ] is related, display significantly diminished metal‐based nucleophilicity relative to the corresponding [FeL 4 ] 2− dianions, and therefore may not be a competitive site of electrophilic attack when other Lewis basic groups are present. However, we have found conditions where Na[ 3 ] can be decarboxylated to regenerate the tetraisocyano dianion Na 2 [ 1 ] in a synthetically reversible fashion.…”

Sustainability in Catalysis - Concept or Contradiction?

“…The synthetic pathways toward such complexes were paved by Walter Hieber and co-workers in the early second half of the 20th century, e.g. formation of 2, 14 4, 15 and 5, 16 while carbonyl-free analogues 3 and 6 were reported more recently by Bitterwolf and Steele 17 and Brennessel and Ellis, 18 respectively.…”

“…the 20th century, e.g. formation of 2, 14 4, 15 and 5, 16 while carbonyl-free analogues 3 and 6 were reported more recently by Bitterwolf and Steele 17 and Brennessel and Ellis, 18 respectively.…”