New phosphites, O2S [(t-Bu)MeC6H2O](2)P(OC6F5)(1), S[Me2C6H2O](2)P(OC6F5) (3), and H2C[(t-Bu)(2)C6H2O](2)P-(OC6F5) (6), a phosphate, S[(t-Bu)MeC6H2O](2)P(O)(OC6F5) (4), and pentaoxyphosphoranes O2S [(t-Bu)MeC6H2O](2)P-(OC6F5)(O2C6Cl4) (2) and S[Me2C6H2O](2)P(OC6F5)(3) (5), all containing pentafluorophenoxy Ligands, have been prepared and characterized by NMR and X-ray studies. Starting with either PCl3 for the phosphites or POCl3 for the phosphate, reactions with diols formed cyclic chlorophosphites or a chlorophosphate, respectively, in situ, followed by condensation with pentafluorophenol to give the products. An oxidative addition reaction of I with a quinone produced 2 while 5 was prepared from P(OC6F5)(3) formed in situ, followed by oxidative addition with a diol. Other than 6, all contained sulfonyl (1 and 2) or sulfur (3-5) donor groups which coordinated with phosphorus to give pseudo trigonal bipyramidal (1 and 3), trigonal bipyramidal (4), and octahedral (2 and 5) geometries. In the presence of OC6F5 ligands, the sulfur atom and oxygen atom of the sulfonyl group exercise similar donor abilities for oxyphosphoranes, which contrasts with previous studies where ligands of lesser electronegativity were employed that showed sulfur to supply stronger donor interaction in displacing oxyphosphoranes toward an octahedral geometry. This leveling effect is attributed to the enhancement of the electrophilicity at phosphorus in the presence of pentafluorophenoxy ligands. In support of earlier work, it is now quantitatively well defined that donor action causes an increase in coordination geometry at phosphorus where the strength of such action increases in the order phosphates < phosphites < oxyphosphoranes.