Desulfurization and N 2 Binding at an Iron Complex Derived from the C-S Activation of Benzothiophene

• Published in: Organometallics Vol. 42; no. 15; pp. 2019 - 2027
• Main Authors: Hooper, Reagan X, Mercado, Brandon Q, Holland, Patrick L
• Format: Journal Article
• Language: English
• Published: United States 14-08-2023
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.3c00220

Metal insertion into the C-S bonds of thiophenes is a facile route to interesting polydentate ligand scaffolds with C and S donors. Here, we describe iron-mediated C-S activation of a diphenylphosphine-functionalized benzothiophene proligand. Metalation of the proligand with "tetrakis(trimethylphosphine)iron" gives an initial five-coordinate, diamagnetic iron(II) species with two PMe
ligands and a dianionic PCS pincer ligand. Upon one-electron reduction, a reactive anionic iron(I) complex is formed. This species then undergoes deep-seated changes, notably cleavage of C-S and C-P bonds in the supporting ligand. Substantial coordination sphere alterations accompany the ligand C-S bond activation, including loss of a sulfur anion from the S-Fe-C metallacycle and reorganization of the two PMe
ligands. The resulting desulfurized six-coordinate PCC iron complex also has an N
ligand
to the vinyl C. Reducing this complex then cleaves a C-P bond in the appended diphenylphosphine, giving a phosphido arm. These ligand transformations demonstrate novel approaches to pincers with thiolates and phosphides, which would be difficult to synthesize using typical methods through free ligand salts.