Standard Enthalpies of Formation for Solid Complexes of Chromium Nitrate with Histidine

摘要

Under the guidance of the phase diagram of the ternary system of Cr(NO_3)_3-His-H_2O, solid complexes of Cr(NO_3)_3 with L-a-Histidine, Cr(His)(NO_3)_3 o 3H_2O (A), Cr(His)_2(NO_3)_3 o 3H_2O (B), and Cr(His)_3(NO_3)_3 o 3H_2O (C) have been prepared in water and characterized by elemental analysis, chemical analysis, IR spectroscopy, and TG-DTG measurements. The constant volume combustion energies of the complexes have been determined by an RBC-II-type rotating-bomb calorimeter, and the standard enthalpies of formation of the complexes have been calculated as well, which are (-1160.22 + - 2.64) kJ mol~(-1), (-1844.91 ± 4.33) kJ mol~(-1), and (-5400.35 + - 5.08) kJ mol~(-1), respectively.