|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5410074||1506553||2016||10 صفحه PDF||سفارش دهید||دانلود رایگان|
- The coordination ability of alkali metal and alkaline earth metal ions with phosphates has been confirmed.
- The (reverse) coordination constants are evaluated in MeCN with protic solvents.
- The interaction increases in the order of Na+Â <Â Li+ and Ba2Â +Â <Â Ca2Â +Â <Â Mg2Â +.
- The concrete evidence in hydrolysis of phosphates and Mg2Â + or Ca2Â + in biochemical systems.
In acetonitrile (MeCN), the specific interactions of alkali metal (M+Â =Â Li+ or Na+) and alkaline earth metal ions (M2Â +Â =Â Mg2Â +, Ca2Â +, or Ba2Â +) with various phosphorus anions, Lâ, i.e., diphenylphosphinate, diphenylphosphate, and bis(4-nitrophenyl)phosphate, have been examined by means of UV-visible spectroscopy. The formation of “reverse-coordinated” or coordinated species, M2L+ or ML+, has been observed in the presence of excess amounts of the metal ions to the anions. Between all the M+ or M2Â + ions and 1.0Â ÃÂ 10âÂ 3Â molÂ dmâÂ 3 diphenylphosphinate ion (n-Bu4N+Â Ph2PO2â), both the precipitation of the non-charged species (ML or ML2) and the successive re-dissolution of the precipitates take place. The addition of the alkaline earth metal ions of just the equi-molar to Lâ causes almost complete dissolution of the precipitates through the soluble ML+ coordinated species. As for the diphenylphosphate ion [n-Bu4N+(PhO)2PO2â], no apparent interaction can be insisted between the alkali metal ions or Mg2Â + and 5.0Â ÃÂ 10âÂ 4Â molÂ dmâÂ 3 diphenylphosphate ion, based on just no precipitation occurrence. Only Na+ and Ba2Â + can cause obvious precipitation with 5.0Â ÃÂ 10âÂ 4Â molÂ dmâÂ 3 bis(4-nitrophenyl)phosphate. A good evidence, however, has been provided by the conductometric titration of 5.0Â ÃÂ 10âÂ 4Â molÂ dmâÂ 3n-Bu4N+(PhO)2PO2â with LiClO4 or Mg(ClO4)2 in MeCN that the “strong” interaction still operate between Lâ and Li+ or Mg2Â + regardless of no precipitation (nor the successive re-dissolution). The addition of protic solvents, such as water, MeOH, or EtOH, influences significantly the chemical interaction between the metal ions and the anions in MeCN. The solubility products (Ksp) and the “reverse coordination” or coordination constants (K2Â =Â [M2L+]/([M+]2[Lâ], K1Â =Â [ML+]/([M2Â +] [Lâ]) have been evaluated for the systems.
The coordination ability of alkali metal (M+) and alkaline earth metal (M2Â +) ions with diphenylphosphinate, diphenylphosphate, and bis(4-nitrophenyl)phosphate ions has been confirmed not only in sole MeCN but also in the binary solvents containing H2O, MeOH, or EtOH.54
Journal: Journal of Molecular Liquids - Volume 217, May 2016, Pages 83-92