Details

Autor(en) / Beteiligte

• Liu, Xiandong
• Cheng, Jun
• Sprik, Michiel
• Lu, Xiancai

Titel

Solution Structures and Acidity Constants of Molybdic Acid

Ist Teil von

• The journal of physical chemistry letters, 2013-09, Vol.4 (17), p.2926-2930

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2013

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Experiment has not been able to discriminate between the oxo (MoO3·(H2O)3) and oxyhydroxide (MoO2(OH)2·(H2O)2) forms of molybdic acid. Using first-principles molecular dynamics based pK a calculation techniques, we identify that MoO2(OH)2.(H2O)2 is the true solution structure and its OH ligands are the acidic site. Simulations at elevated temperatures up to 573 K show an encouraging agreement between calculated and experimental pK a’s, which validates our method of prediction of subtle pH-dependent speciation in hydrothermal solutions. We find that molybdate species have highly volatile pH- and temperature-dependent coordinations, which is related with the experimentally observed variability in Mo coordination of polyoxometalates (POMs). These results form a physical basis for understanding the properties of Mo in numerous lab and natural processes ranging from formation of POMs to transport and deposition mechanisms in crustal fluids.