Synthesis and crystal structure of KBi(C6H4O7) · 3.5H2O

Structural characteristics of amorphous K-Bi citrate (De-Nol) and its aqueous solutions from EXAFS spectra

“…We are aware of at least nine different crystalline forms of bismuth citrate, which were characterized by X-ray diffraction [2,[4][5][6][7][8][9][10][11]. In these compounds, the main structural element is a stable dimeric (cit 4− )BiBi(cit 4− ) moiety [4][5][6][7][9][10][11]. Special attention should also be paid to the structural features of a crystal composed of 12-nuclear (NH 4 ) 12 10 clusters and its behavior in solutions [8].…”

“…A number of factors hinder the determination of the structure of these compounds: 1) possible variation of Bi coordination number from 3 to 10 [1]; 2) presence of other cations (potassium and/or ammonium) in the complex; 3) dependence of the compound composition on the initial solution concentration and the component ratio in it, e.g., Bi(NO 3 ) 3 and K 3 (HCit) [2,3]. We are aware of at least nine different crystalline forms of bismuth citrate, which were characterized by X-ray diffraction [2,[4][5][6][7][8][9][10][11]. In these compounds, the main structural element is a stable dimeric (cit 4− )BiBi(cit 4− ) moiety [4][5][6][7][9][10][11].…”

“…Special attention should also be paid to the structural features of a crystal composed of 12-nuclear (NH 4 ) 12 10 clusters and its behavior in solutions [8]. Note that the mentioned diffraction measurements of crystals were performed in sealed capillaries together with the mother liquor [5][6][7][8]11]. During the crystal growth water molecules become involved in the structure-forming process.…”

“…During the crystal growth water molecules become involved in the structure-forming process. By means of a system of hydrogen bonds they organize the structural elements into three-dimensional frameworks [1,3,7,[9][10][11]. Therefore even minor alterations in the hydrate composition can cause considerable changes in the structure of compounds.…”

“…Although biologically active complexes based on Bi citrate have long been widely used in medicine, studies of the structure of the complexes have been started relatively recently [4][5][6][7][8][9][10][11]. A number of factors hinder the determination of the structure of these compounds: 1) possible variation of Bi coordination number from 3 to 10 [1]; 2) presence of other cations (potassium and/or ammonium) in the complex; 3) dependence of the compound composition on the initial solution concentration and the component ratio in it, e.g., Bi(NO 3 ) 3 and K 3 (HCit) [2,3].…”