Symmetric geminal bisphosphinic acids RR´C[P(CH₃)(O)OH]₂ - NMR and analytical studies

Abstract

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 δ_P of CH₃C(OH)[P(CH₃)(O)OH]₂ are determined by ³¹P{¹H} NMR controlled titrations of 2a.

Graphical Abstract

Keywords:

• Bisphosphinic acids
• RR´C[P(CH₃)(O)OH]₂
• NMR
• analytics
• NMR controlled titration

Acknowledgement

Thanks are due to Miss Beate Rau for help with literature, sample preparation and in particular for running patiently good NMR spectra. In addition we wish to thank Prof. Dr. Jürgen Voss, Hamburg, for helpful suggestions and literature concerning the structural interpretation of NMR data of thiazole and benzothiazol derivatives. Special thanks are due to Prof. Dr. F. H. Ebetino for publications on bisphosphonates and related structures.

Disclosure statement

No potential conflict of interest was reported by the authors.