Reactions of Ferrocenium Hexafluorophosphate with P−OR Nucleophiles Give Ring C−H Functionalization or Ring Replacement Products Depending on the Phosphorus Reagent. Issue 16 (8th April 2021)

• Record Type: Journal Article
• Authors: Chamkin, Aleksandr A.; Krivykh, Vasily V.; Kreindlin, Arkady Z.; Dolgushin, Fedor M.; Ustynyuk, Nikolai A.
• Is Part Of: European journal of inorganic chemistry. Issue 16(2021)
• Page Start: 1601
• Page End: 1610
• Publication Date: 2021-04-08
• Subjects: Density functional calculations -- Ferrocenium cation -- Ferrocenylphosphonium salts -- Metallocenes -- Phosphites; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202100153
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Ferrocenium hexafluorophosphate reacts with different P−OR nucleophiles (PR3 ) in CH2 Cl2 at room temperature to give either half‐sandwich complexes [CpFe(PR3 )3 ](PF6 ) (PR3 =P(OMe)3, P(OEt)3, PhP(OMe)2 ) or ferrocenylphosphonium salts [CpFe(C5 H4 PR3 )](PF6 ) (PR3 = i Pr2 P(OMe), i Pr2 P(OEt)). Mixtures of both products are formed for some other nucleophiles (PR3 =Ph2 P(OMe), Ph2 P(OEt), PhP(O i Pr)2 ). The mechanism of the former reaction was established using DFT calculations. This reaction pathway is especially characteristic of π‐acceptor nucleophiles, which is presumably explained by their ability to stabilize the 19e intermediates. The result of the reaction with tertiary phosphines, aminophosphines, and P−OR nucleophiles can be reliably predicted based on the values of the Tolman electronic parameter (below 2070 cm −1 – only ferrocenylphosphonium salt, in between 2073 cm −1 and 2080 cm −1 – only half‐sandwich complex, and in the range from 2070 cm −1 to 2073 cm −1 – mixtures of both products). Abstract : The reactions of ferrocenium salts with phosphorus nucleophiles can proceed in two completely different pathways resulting either in C−H functionalization of the cyclopentadienyl ring or in the entire replacement of this ring. It was found that the reaction outcome strongly depends on the Tolman electronic parameter of a nucleophile. The mechanism of the unusual cyclopentadienyl replacement was described.