Issue 22, 2022

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

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.

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

Supplementary files

Article information

Article type
Paper
Submitted
08 اپریل 2022
Accepted
19 میٔ 2022
First published
20 میٔ 2022
This article is Open Access
Creative Commons BY license

Dalton Trans., 2022,51, 8906-8913

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

C. Branfoot, P. G. Pringle, N. E. Pridmore, T. A. Young and D. F. Wass, Dalton Trans., 2022, 51, 8906 DOI: 10.1039/D2DT01093C

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