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Updated: Oct 5, 2025

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Stereochemical Behavior of Pairs of P-stereogenic Phosphanyl Groups at the Dimethylxanthene Backbone
Karel Škoch1,2, Constantin G Daniliuc1, Marcel Müller3
1Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149, Münster, Germany.
Abstract:
The P-stereogenic bis(phosphanes) 7 and 9, featuring pairs of P(Mes)-ethynyl or vinyl substituents at the dimethyl xanthene backbone show rather low barriers of stereochemical inversion at phosphorus. π-Conjugative effects are probably causing these low inversion barriers. Compound 7 reacted with B(C6 F5 )3 to form the nine-membered heterocyclic product 10, featuring a [P]-C≡C-B(C6 F5 )3 substituent. Compound 7 was converted to the bis[P(Mes)vinyl] xanthene derivative 9, which gave the zwitterionic P(H)(Mes)-CH=CH-B(C6 F5 )3 containing product 16 upon treatment with B(C6 F5 )3 . Thermally induced epimerization barriers at phosphorus of ca. 20 to 27 kcal mol-1 were calculated by DFT for the alkenyl- and alkynyl-P derived systems 6 to 9, 15 and 16 and experimentally determined for the examples 7 and 16.
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