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Heterometathesis of diphosphanes (R2P–PR2) with dichalcogenides (R′E–ER′, E = O, S, Se, Te)

Branfoot, Callum, Pringle, Paul G., Pridmore, Natalie E., Young, Tom A. and Wass, Duncan F. ORCID: https://orcid.org/0000-0002-0356-7067 2022. Heterometathesis of diphosphanes (R2P–PR2) with dichalcogenides (R′E–ER′, E = O, S, Se, Te). Dalton Transactions 51 (22) , pp. 8906-8913. 10.1039/D2DT01093C

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Abstract

The reactions of R2P–PR2 with R′E–ER′, (where E = Se, S, O, Te) to give R2P–ER′ have been explored experimentally and computationally. The reaction of Ph2P–PPh2 with PhSe–SePh gives Ph2P–SePh (1) rapidly and quantitatively. The P–P/Se–Se reaction is inhibited by the addition of the radical scavenger TEMPO which is consistent with a radical mechanism for the heterometathesis reaction. Compound 1 has been fully characterised, including by X-ray crystallography. A range of other Ar2P–SeR (R = Ph, nBu or CH2CH2CO2H) have also been prepared and characterised. The reaction of 1 with [Mo(CO)4(nbd)] (nbd = norbornadiene) gives two products which, from their characteristic 31P NMR data, have been identified as cis-[Mo(CO)4(Ph2PSePh–P)2] (8) and the mixed-donor complex cis-[Mo(CO)4(Ph2P–SePh–P)(Ph2P–SePh–Se)] (9). It is deduced that the P and Se atoms in ligand 1 have comparable capacity to coordinate to Mo(0). The reaction of Ph2P–PPh2 with PhS–SPh gives Ph2P–SPh (2) quantitatively but no reaction was observed between Ph2P–PPh2 and PhTe–TePh. Heterometathesis between Ph2P–PPh2 and tBuO–OtBu does not occur thermally but has been observed under UV irradiation to give Ph2P–OtBu along with P(V) oxidation by-products. DFT calculations have been carried out to illuminate why heterometatheses with dichalcogenides R′E–ER′ occur readily when E = S and Se but not when E = O and Te. The calculations show that heterometathesis is predicted to be thermodynamically favourable for E = O, S and Se and unfavourable for E = Te. The fact that a metathesis reaction between Ph2P–PPh2 with tBuO–OtBu is not observed in the absence of UV radiation, is therefore due to kinetics.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Additional Information: Attribution 3.0 Unported (CC BY 3.0)
Publisher: Royal Society of Chemistry
ISSN: 1477-9226
Funders: EPSRC
Date of First Compliant Deposit: 1 July 2022
Date of Acceptance: 19 May 2022
Last Modified: 25 Oct 2022 14:21
URI: https://orca.cardiff.ac.uk/id/eprint/150956

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