Symmetric Geminal Bisphosphinic Acids RR´C[P(CH3)(O)OH]2 - NMR and Analytical Studies

Four bisphosphinic acids RR´C[P(CH3)(O)OH]2 are characterized by 1H, 13C{1H}, and 31P{1H} NMR data. H3C-P-C-P-CH3 skeletons give rise to [A3X]2 spin systems. Some algebraic equations are derived for manual analysis of [A3X]2 spectra. HR NMR data for heteroaromatic substituents R in RC(H)[P(CH3)(O)OH]2 are reported. Dissociation constants and ion-specific chemical shifts dP of CH3C(OH)[P(CH3)(O)OH]2 are determined by 31{1H} NMR controlled titrations of 2a