HL2[P(1,2-O(2)C(6)H4)(3)] (L = DMSO or DMF): A Convenient Proton Source with a Weakly Basic Phosphorus(V) Anion

Treating phosphorus pentachloride with catechol (3 equiv) followed by the addition of dimethylsulfoxide (DMSO) or dimethylformamide (DMF) affords isolable bronsted acids of tris- (o-phenylenedioxy)phosphate anion, [p(1,2-O2C6H4)(3)](-). Specifically. H(DMSO)(2)[P(1,2-O2C6H4)(3)] and H(DMF)(2)[P(1,2-O2C6H4)(3)] have been isolated as crystalline solids. The downfield shifts of the acidic proton in their H-1 NMR spectra are consistent with its expected high acidity. The molecular structures of H(DMSO)(2)[P(1,2-O2C6H4)(3)] and H(DMF)(2)[P(1,2-O2C6H4)(3)] reveal that the protons in each are O-bound by either DMSO (x2) or DMF (x2). The N-H stretching frequency for the Oct(3)NH[P(1,2-O2C6H4)(3)] ((V) over bar (N-H) =3129 cm(-1)) is identical to that observed for trioctylammonium tetrafluoroborate ((v) over bar (N-H) = 3129 cm(-1)), suggesting that the basicity of these two weakly coordinating anions is similar. A preliminary investigation of the effectiveness of H(DMF)(2)[p(1,2-O2C6H4] in the protonolysis of metal-alkyl bonds was undertaken. Treating (dppe) pdMe(2) [dppe = 1,2-bis(diphenylphosphino)ethane] with H(DMF)(2)[P(1,2-O2C6H4)(3)] affords either [(dppe)pd(NCMe)Me][P(1,2-O2C6H4)(3) (1:1 ratio) or [(dppe)pd(NCMe)(2)(][P(1,2-O2C6H4)(3)](2) (1:2 ratio), both of which are structurally characterized.