Ternary antimony–chalcogen iron carbonyl complexes and their derivatives: Syntheses, structures, reactivities, and low-energy-gap characteristics

Abstract

A novel series of ternary antimony–chalcogen iron carbonyl clusters, [{SbTeFe3(CO)9}{Te2Fe3(CO)9}]– (1), [{SbSeFe3(CO)9}{Se2Fe2(CO)6}]– (2), and [{SbSFe3(CO)9}{SFe3(CO)9}]– (3), were synthesized in moderate yields from reactions of [EFe3(CO)9]2– (E = Te, Se, S) with SbCl3. X-ray analyses revealed that complexes 1–3 each can be viewed as a square pyramidal geometry [SbEFe3(CO)9] (E = Te, Se, S), where the Sb atom was further coordinated with pendant cluster fragments [Te2Fe3(CO)9], [Se2Fe2(CO)6], and [SFe3(CO)9], respectively. Interestingly, the oxidation state of the Sb atom in complexes 1–3 was 0, which was evidenced by XPS and XANES. Complexes 1–3 showed high electrophilicity toward a series of metal carbonylates, which produced transmetallated products, the “spiked” square pyramidal complexes [{SbEFe3(CO)9}{M(CO)x}] [M(CO)x = Fe(CO)4, E = Te, 1-Fe; Se, 2-Fe; S, 3-Fe; M(CO)x = Cr(CO)5, Se, 2-Cr; S, 3-Cr] and the Mn(CO)4-bridged di-ESbFe3(CO)9-based clusters [{SbEFe3(CO)9}2Mn(CO)4]– (E = Se, 2-Mn; S, 3-Mn). Furthermore, the diffuse reflectance spectra showed that these ternary and quaternary antimony-chalcogenide metal carbonyl clusters possessed low energy gaps of 0.84–1.48 eV, suggesting possible electron transports within the frameworks, which was supported by crystal packings and DFT calculations.