Tetrasubstituted Selenophenes from the Stepwise Assembly of Molecular Fragments on a Diiron Frame and Final Cleavage of a Bridging Alkylidene

Abstract

A series of 2,3-dicarboxylato-5-acetyl-4-aminoselenophenes, 5a – j , was obtained via the uncommon assembly of building blocks on a diiron platform, starting from commercial [Fe 2 Cp 2 (CO) 4 ] through the stepwise formation of diiron complexes [ 2a – d ]CF 3 SO 3 , 3a – d , and 4a – j . The selenophene-substituted bridging alkylidene ligand in 4a – j is removed from coordination upon treatment with water in air under mild conditions (ambient temperature in most cases), affording 5a – j in good to excellent yields. This process is highly selective and is accompanied by the disruption of the organometallic scaffold: cyclopentadiene (CpH) and lepidocrocite (γ-FeO(OH)) were identified by NMR and Raman analyses at the end of one representative reaction. The straightforward cleavage of the linkage between a bridging Fischer alkylidene and two (or more) metal centers, as observed here, is an unprecedented reaction in organometallic chemistry: in the present case, the carbene function is converted to a ketone which is incorporated into the organic product. DFT calculations and electrochemical experiments were carried out to give insight into the release of the selenophene-alkylidene ligand. Compounds 5a – j were fully characterized by elemental analysis, mass spectrometry, IR, and multinuclear NMR spectroscopy and by X-ray diffraction and cyclic voltammetry in one case.

When ferrocene and diiron organometallics meet: triiron vinyliminium complexes exhibit strong cytotoxicity and cancer cell selectivity

“…23 Note that the versatile vinyliminium ligand is susceptible to nucleophilic attack by various functional groups, 32 and the resulting derivatives may undergo fast decomposition in aqueous solutions. 37…”

A Strategy to Conjugate Bioactive Fragments to Cytotoxic Diiron Bis(cyclopentadienyl) Complexes

“…Organic reactants were purchased from TCI Europe or Merck and were of the highest purity available, while solvents were purchased from Merck (petroleum ether, bp 40–60 °C). The compounds ALK A1 , , [Fe 2 Cp 2 (CO) 2 (μ-CO)­{μ-CNMe­(R)}]­CF 3 SO 3 (R = Me, [ 1a ]­CF 3 SO 3 ; R = Xyl = 2,6-C 6 H 3 Me 2 , [ 1b ]­CF 3 SO 3 ), [ 11 ]­CF 3 SO 3 , [ 12 ]­CF 3 SO 3 , and [ 14 ]­CF 3 SO 3 and [ 13 ]­CF 3 SO 3 were prepared according to the literature. The synthesis of alkynes was carried out under an N 2 atmosphere using standard Schlenk techniques, and solvents were distilled before use from the appropriate drying agents under N 2 ; all other operations were conducted in air.…”

Aminocarbyne ligands in organometallic chemistry

“…It should be mentioned here that the stepwise modification of vinyliminium ligands may lead to rare tetrasubstituted selenophenes, which can be finally removed from coordination in mild conditions (treatment with water in air). This is a significant use of diiron aminocarbyne complexes as easily available and convenient organometallic reagents for the synthesis of functionalized organics otherwise not accessible [143].…”