Piano Stool Aminoalkylidene‐Ferracyclopentenone Complexes from Bimetallic Precursors: Synthesis and Cytotoxicity Data

Abstract

The reaction of pyrrolidine with a series of cationic diiron cyclopentadienyl complexes containing a bridging vinyliminium ligand gives access to piano stool monoiron complexes based on a five-membered metallacycle that includes a vinyl-aminoalkylidene moiety, in moderate to high yields. The resulting metallacyclic motif (aminoalkylidene-ferracyclopentenone) is unique in organometallic chemistry and is partially preconstructed on the dinuclear frame. The monoiron products were fully characterized by elemental analysis, IR and multi-nuclear NMR spectroscopy, and in a number of cases by X-ray diffraction and cyclic voltammetry. They are robust in aqueous solutions and generally unreactive towards alkylating agents in organic solvents. However, a cationic derivative was prepared in high yield by methylation of a 2-pyridyl group. The cytotoxicity of both neutral and ionic complexes was assessed on cancerous (A2780 and A280cisR) and non-cancerous (HEK293) cell lines, revealing the influence of local structural modifications on the antiproliferative activity and the selectivity of the compounds.

Exploring the Anticancer Potential of Diiron Bis-cyclopentadienyl Complexes with Bridging Hydrocarbyl Ligands: Behavior in Aqueous Media and In Vitro Cytotoxicity

“…36 Experiments carried out under analogous conditions on some diiron vinyliminium complexes (Figure 1, IV) provided comparable reduction potential values, 36,37 and it has been hypothesized that the monoelectron reduction of the latter species in the cells is implicated in their antiproliferative activity. 12,38 Furthermore, it is well documented that the one-electron reduction of 4 enhances the reactivity of this complex, and in particular the CO ligands become more labile and thus susceptible to fast substitution reactions. 39 In combination, these features suggest that the reduction of cationic thiocarbyne (4) and aminocarbyne complexes (5, 6, 10, 11) might play a role in their cytotoxic activity.…”

Mono-, Di- and Tetra-iron Complexes with Selenium or Sulphur Functionalized Vinyliminium Ligands: Synthesis, Structural Characterization and Antiproliferative Activity

“…This formal [C 2 H] + /C 2 E substitution (E = S, Se) presumably proceeds through the initial single-electron reduction of the cationic part of 1a-c. Consistent with this hypothesis, the monoiron complex 3, maintaining the C 2 -H unit, is a side product of the reaction leading to 2a, and may be viewed as the result of selenium incorporation along a fragmentation process initiated by electron transfer to 1a [51]. The chalcogenido moiety in 2a-d is readily oxidized with I2 to the dimeric iodide salts 4a-d, containing an E-E bridge (77%-93%) [48].…”

Construction of a Functionalized Selenophene‐Allylidene Ligand via Alkyne Double Action at a Diiron Complex

“…The reaction leading to 3a is not selective, since a small amount of the monoiron complex 4 was produced, which was recovered in 31 % yield after work‐up. Complex 4 , maintaining the C 2 –H unit, might be viewed as the result of selenium incorporation along a fragmentation process initiated by electron transfer to 2a . Compound 4 was identified on the basis of a comparison of its IR and NMR features with those of the strictly analogous species [FeCp(CO){SeC 1 (NMe 2 )C 2 HC 3 (Me)}], crystallographically characterized and recently published.…”