| A novel class of anionic tripod organophosphorus ligands which are uninegative and potentially tridentate, six-electron donors have been synthesized and characterized. They contain three phosphorus atoms attached to a central carbon atom, with each phosphorus bonded to a chalcogen (oxygen, sulfur or selenium), and are obtained by proton abstraction from the neutral parent ligands of general formula, {(C(,6)H(,5))(,2)P(X)}{(C(,6)H(,5))(,2)P(Y)}{(C(,6)H(,5))(,2)P(Z)}CH, HTris(X, Y, Z) where X, Y and Z are various combinations of the chalcogens. Tris(diphenylthiophosphinoyl)methane, HTrisS(,3), the first compound in the series, was reported earlier. The present work has extended this rare class of ligands to include {Ph(,2)P(O)}(,n){Ph(,2)P(S)}(,3-n)CH (n = 1, 2, 3) and {Ph(,2)P(S)}(,2){Ph(,2)P(Se)}CH. Because of the bulky phenyl groups on the phosphorus, and large size of some of the chalcogens, restricted rotation about the phosphorus-methine carbon bond was observed at low temperature in some of the HTris(X, Y, Z) compounds, such as HTrisS(,2)Se and HTrisS(,2)O, and studied by variable temperature phosphorus-31 Nuclear Magnetic Resonance (NMR) techniques.;Copper (I) and silver (I) complexes of the general formula TrisS(,3)ML, where L is a tertiary phosphine, have been synthesized and characterized. X-ray structural analysis of TrisS(,3)Ag(n-Bu(,3)P) revealed a cage structure with the silver complexed in pseudotetrahedral geometry to three sulfur atoms and the phosphorus of the tertiary phosphine.;The reaction of TrisO(,3)('-) with iron(II) did not produce the expected ferrocene-like structure (TrisO(,3))(,2)Fe, but instead formed a crystalline product whose preliminary X-ray structural analysis indicates that the TrisO(,3)('-) ligand is bound in a bidentate fashion with the third phosphoryl remaining uncoordinated.;Additional preliminary results of the chemistry of these tripod ligands and their anionic derivatives, especially their coordination chemistry and prospectives for further developments are discussed.;The anions were prepared by the reaction of HTrisS(,n)O(,3-n) (n = 0,1,2 and 3) with lithium methoxide in methanol and isolated as the lithium salt, Li('+){TrisS(,n)O(,3-n)}('-) or in several cases by metathesis with a quarternary onium salt to form, e.g., {n-Bu(,4)N}('+){TrisS(,3)}('-) and {n-BuPh(,3)P}('+){TrisS(,3)}('-). X-ray structural analysis of {n-Bu(,4)N}('+){TrisS(,3)}('-) showed that the anion has essentially planar geometry at the central carbon with a mean P-C-P bond angle of 119.9(DEGREES). |
