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Updated: Oct 3, 2026

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)
Published on: November 22, 2016
Increased Coordination via Sulfur Donor Action in Cyclic Pentaoxyphosphoranes and the Parent Cyclic Phosphite.
Paul Sood1, A. Chandrasekaran, Roberta O. Day
1Department of Chemistry, Box 34510, University of Massachusetts, Amherst, Massachusetts 01003-4510.
Abstract:
The pentafluorophenoxy ligand was introduced into the new cyclic pentaoxyphosphoranes S[(t-Bu)MeC(6)H(2)O](2)P(OC(6)F(5))(O(2)C(6)Cl(4)) (1), S[(t-Bu)MeC(6)H(2)O](2)P(OC(6)F(5))(O(2)C(14)H(8)) (2), and S[(t-Bu)MeC(6)H(2)O](2)P(OC(6)F(5))(3) (3). X-ray analysis revealed hexacoordinate structures formed by sulfur donor action present as a bridging atom in flexible eight-membered rings for 1-3. X-ray analysis showed that sulfur coordination also occurred with the same type of ring system as part of the phosphite S[(t-Bu)MeC(6)H(2)O](2)P(OC(6)F(5)) (4) to give a pseudo-trigonal-bipyramidal geometry. The pentafluorophenoxy ligand present in the oxyphosphoranes 1-3 as well as in the phosphite 4 acts comparably to a chlorine atom in its ability to enhance phosphorus electrophilicity as measured by the degree of P-S coordination and geometrical displacement toward a more highly coordinated state. The phosphite 4 has a P-S donor distance of 2.876(2) Å, considerably longer than the range of P-S distances from 2.366(3) to 2.495(2) Å obtained for the pentaoxyphosphoranes 1-3. These data express quantitatively the relative electrophilicity of phosphorus as a function of coordination number and substituent composition.
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