Synthesis and structures of the first bismuth-ester complexes using heterobifunctional thiolate anchored ligands and mass spectrometric identification of ligand-bridged derivatives.

The first systematic series of bismuth complexes involving ester donors, Bi(SCH2C(O)OCH2CH3)Cl2, Bi(SCH2C(O)OCH3)2Cl, and Bi(SCH2COOCH3)3, has been isolated and characterized by spectroscopic (IR, Raman) and X-ray crystallographic data. In addition, these and other species have been identified by electron-impact, electrospray, and atmospheric pressure chemical ionization mass sprectometry. The generally applicable synthetic methodology involves the use of heterobifunctional ligands containing a thiolate moiety as an anchor to facilitate coordinate interactions between weak donors (carbonyls) and weak acids (bismuth). The bifunctional nature of the ligands is manifested in both chelating and bridging roles. Important comparisons can be made with the pharmaceutical agent “colloidal bismuth subcitrate” (CBS). The observations allow for a new appreciation of bioactive bismuth compounds, by providing an approach to study the interaction of biorelevant functional groups with bismuth.