Investigating Metal–Metal Bond Polarization in a Heteroleptic Tris-Ylide Diiron System

• Published in: Inorganic chemistry Vol. 62; no. 29; pp. 11487 - 11499
• Main Authors: Spentzos, Ariana Z., May, Sam R., Confer, Alex M., Gau, Michael R., Carroll, Patrick J., Goldberg, David P., Tomson, Neil C.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.07.2023
• ISSN: 0020-1669; 1520-510X; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c01068

This article describes the synthesis, characterization, and S-atom transfer reactivity of a series of C 3v -symmetric diiron complexes. The iron centers in each complex are coordinated in distinct ligand environments, with one (FeN) bound in a pseudo-trigonal bipyramidal geometry by three phosphinimine nitrogens in the equatorial plane, a tertiary amine, and the second metal center (FeC). FeC is coordinated, in turn, by FeN, three ylidic carbons in a trigonal plane, and, in certain cases, by an axial oxygen donor. The three alkyl donors at FeC form through the reduction of the appended NPMe3 arms of the monometallic parent complex. The complexes were studied crystallographically, spectroscopically (NMR, UV–vis, and Mössbauer), and computationally (DFT, CASSCF) and found to be high-spin throughout, with short Fe–Fe distances that belie weak orbital overlap between the two metals. Further, the redox nature of this series allowed for the determination that oxidation is localized to the FeC. S-atom transfer chemistry resulted in the formal insertion of a S atom into the Fe–Fe bond of the reduced diiron complex to form a mixture of Fe4S and Fe4S2 products.