Redox-Active Phosphorus Ligands Bearing a [4Fe−4C] Core Substituent

Abstract

Reaction of [(η5-C5H4Me)4Fe4(HCCH)(HCCBr)](PF6) (1) with HPPh2 in the presence of NEt3, followed by treatment of [Cp2Co], afforded [(η5-C5H4Me)4Fe4(HCCH)(HCC−PPh2)] (2). The electron-rich [4Fe−4C] core substituent leads to the extremely electron-releasing character of the phosphine part, estimated by the J PSe coupling constant of the corresponding selenide [(η5-C5H4Me)4Fe4(HCCH)(HCC−P(Se)Ph2)] (3). Reaction of 2 with [AuCl(SMe2)] gave [(η5-C5H4Me)4Fe4(HCCH)(HCC−P(AuCl)Ph2)] (4). The cyclic voltammogram of 4 shows two reversible one-electron oxidation waves, indicating the existence of one- and two-electron oxidized forms.

Noninnocent Behavior of Bidentate Amidophosphido [NP]2– Ligands upon Coordination to Copper

“…Most redox-active ligands to date are derived from either diimines or 1,2-disubstituted benzene rings and involve combinations of nitrogen, oxygen, and sulfur donors. ,− Perhaps surprisingly, there have been limited reports of similar arene-based redox-active ligand frameworks containing phosphorus donor atoms. The exploration of phosphorus-containing redox-active ligands has been mostly confined to metallocenes substituted with phosphine donors (i.e., dppf and derivatives thereof) , and metal clusters appended to phosphine donors …”