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Spectroscopic and DFT Study of RhIII Chloro Complex Transformation in Alkaline Solutions. / Vasilchenko, Danila B.; Berdyugin, Semen N.; Korenev, Sergey V. et al.
In: Inorganic Chemistry, Vol. 56, No. 17, 05.09.2017, p. 10724-10734.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Spectroscopic and DFT Study of RhIII Chloro Complex Transformation in Alkaline Solutions
AU - Vasilchenko, Danila B.
AU - Berdyugin, Semen N.
AU - Korenev, Sergey V.
AU - O'Kennedy, Sean
AU - Gerber, Wilhelmus J.
N1 - Publisher Copyright: © 2017 American Chemical Society.
PY - 2017/9/5
Y1 - 2017/9/5
N2 - The hydrolysis of [RhCl6]3- in NaOH-water solutions was studied by spectrophotometric methods. The reaction proceeds via successive substitution of chloride with hydroxide to quantitatively form [Rh(OH)6]3-. Ligand substitution kinetics was studied in an aqueous 0.434-1.085 M NaOH matrix in the temperature range 5.5-15.3 °C. Transformation of [RhCl6]3- into [RhCl5(OH)]3- was found to be the rate-determining step with activation parameters of ΔH† = 105 ± 4 kJ mol-1 and ΔS†= 59 ± 10 J K-1 mol-1. The coordinated hydroxo ligand(s) induces rapid ligand substitution to form [Rh(OH)6]3-. By simulating ligand substitution as a dissociative mechanism, using density functional theory (DFT), we can now explain the relatively fast and slow kinetics of chloride substitution in basic and acidic matrices, respectively. Moreover, the DFT calculated activation energies corroborated experimental data that the kinetic stereochemical sequence of [RhCl6]3- hydrolysis in an acidic solution proceeds as [RhCl6]3- → [RhCl5(H2O)]2- → cis-[RhCl4(H2O)2]-. However, DFT calculations predict in a basic solution the trans route of substitution [RhCl6]3- → [RhCl5(OH)]3- → trans-[RhCl4(OH)2]3- is kinetically favored.
AB - The hydrolysis of [RhCl6]3- in NaOH-water solutions was studied by spectrophotometric methods. The reaction proceeds via successive substitution of chloride with hydroxide to quantitatively form [Rh(OH)6]3-. Ligand substitution kinetics was studied in an aqueous 0.434-1.085 M NaOH matrix in the temperature range 5.5-15.3 °C. Transformation of [RhCl6]3- into [RhCl5(OH)]3- was found to be the rate-determining step with activation parameters of ΔH† = 105 ± 4 kJ mol-1 and ΔS†= 59 ± 10 J K-1 mol-1. The coordinated hydroxo ligand(s) induces rapid ligand substitution to form [Rh(OH)6]3-. By simulating ligand substitution as a dissociative mechanism, using density functional theory (DFT), we can now explain the relatively fast and slow kinetics of chloride substitution in basic and acidic matrices, respectively. Moreover, the DFT calculated activation energies corroborated experimental data that the kinetic stereochemical sequence of [RhCl6]3- hydrolysis in an acidic solution proceeds as [RhCl6]3- → [RhCl5(H2O)]2- → cis-[RhCl4(H2O)2]-. However, DFT calculations predict in a basic solution the trans route of substitution [RhCl6]3- → [RhCl5(OH)]3- → trans-[RhCl4(OH)2]3- is kinetically favored.
KW - DENSITY-FUNCTIONAL THEORY
KW - ABSORPTION INTENSITY CALCULATIONS
KW - BASIS-SETS
KW - VARIABLE-TEMPERATURE
KW - AQUEOUS-SOLUTION
KW - 2ND DERIVATIVES
KW - SCREENING MODEL
KW - WATER EXCHANGE
KW - RHODIUM(III)
KW - KINETICS
UR - http://www.scopus.com/inward/record.url?scp=85028929197&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.7b01672
DO - 10.1021/acs.inorgchem.7b01672
M3 - Article
AN - SCOPUS:85028929197
VL - 56
SP - 10724
EP - 10734
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 17
ER -
ID: 9913960