Coulomb repulsion versus cycloaddition : formation of anionic four-membered rings from sodium phosphaethynolate, Na(OCP)

Heift, Dominikus, Benkő, Zoltán and Grützmacher, Hansjörg (2014) Coulomb repulsion versus cycloaddition : formation of anionic four-membered rings from sodium phosphaethynolate, Na(OCP). Dalton Transactions, 43(2), pp. 831-840. ISSN (print) 1477-9226

Official URL: https://doi.org/10.1039/C3DT52359D

Abstract

Carbon dioxide and two equivalents of Na(OCP) form, in an equilibrium reaction, a CO2 adduct of the composition Na2(P2C3O4). The anion of this salt, [O2C–P(CO)2P]2−, is built up by a four-membered 1,3-diphosphetane-2,4-dione ring and a carboxylate unit attached to one of the phosphorus atoms. A remarkable π-delocalization was observed within the OCPCO moiety. The stepwise reaction mechanism leading to Na2(P2C3O4) was investigated with quantum chemical calculations. Accompanied by the release of CO2, Na2(P2C3O4) reacts with both 2-iodopropane and 4,4′,4′′-trimethoxytriphenylmethyl chloride to form four-membered cyclic anions. For comparison the analogous reactions were performed with Na(OCP) instead of Na2(P2C3O4) and the results are discussed in detail.

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