Polyphosphine anion radicals

Abstract

Electron spin resonance (esr) spectra have been obtained for the anion radicals of 1,2,3,4-tetrakis(trifluoromethyl)-l,2-di- (CF3C) 2(PCF3)2, and l,2,3,4,5-pentakis(trifluoromethyl)-l,2,3-triphosphacyclopent-4-ene, (CF3C)2(PCF3)3, prepared by electrolytic reduction at low temperature. The observed 19F and 31P hyperfine coupling constants indicate that the unpaired electron is localized mainly in the carbon-carbon double bond and that little delocalization to the phosphorus atoms occurs.Reduction of the two compounds with alkali metals led to anion radicals of decomposition products of the parent phosphines. Attempts to generate anion radicals from the cyclopolyphosphines, (CF3P)4 and (CH3P)5, or 3,4-bis(trifluoromethyl)-l,2-dithietene, (CF3C)2S2, were unsuccessful.

A Convenient Synthesis of New Isolable Phosphaalkenes Using the Base-Induced Rearrangement of Secondary Vinylphosphines

“…The 2,6-bis(trifluoromethyl)phenyl and 2,4,6-tris(trifluoromethyl)phenyl (Ar F ) substituents are formally “mesityl analogues”, and they have been used extensively in the chemistry of group 15 elements. − In low-coordinate phosphorus chemistry, Ar F groups have been employed in the synthesis of stable diphosphenes (Ar F PPAr F ), − iminophosphines (Ar F PNAr F ), crystalline phosphenium salts (Ar F PNR 2 + ), and phosphides (Ar F PR - ). , These fluoroaryl groups are able to stabilize low-coordinate phosphorus compounds due to their moderate steric bulk (between Mes and Mes*), electron-withdrawing abilities, and the weak donor properties of the ortho -CF 3 groups in combination with the resistance of the C−F bonds to insertion reactions. We became interested in using Ar F groups for phosphaalkenes after observing the intramolecular C−H activation of the Mes* group (Mes* = 2,4,6- t Bu 3 C 6 H 2 −) by a transient phosphenium ion in the attempted polymerization of the phosphaalkene Mes*PCH 2 with Lewis and protic acids …”

“…The 2,6-bis(trifluoromethyl)phenyl and 2,4,6-tris(trifluoromethyl)phenyl (Ar F ) substituents are formally "mesityl analogues", and they have been used extensively in the chemistry of group 15 elements. [11][12][13][14][15][16][17][18][19][20][21][22][23] In low-coordinate phosphorus chemistry, Ar F groups have been employed in the synthesis of stable diphosphenes (Ar F PdPAr F ), [11][12][13] iminophosphines (Ar F PdNAr F ), 14 crystalline phosphenium salts (Ar F PNR 2 + ), 15 and phosphides (Ar F PR -). 16,17 These fluoroaryl groups are able to stabilize low-coordinate phosphorus compounds due to their moderate steric bulk (between Mes and Mes*), electron-withdrawing abilities, and the weak donor properties of the ortho-CF 3 groups in combination with the resistance of the C-F bonds to insertion reactions.…”