Speciation of chromium aqua and chloro complexes in hydrochloric acid solutions at 298 K

Masahito Uchikoshi; Daisuke Akiyama; Ken'ichi Kimijima; Kozo Shinoda

doi:10.1039/d2ra06279h

Speciation of chromium aqua and chloro complexes in hydrochloric acid solutions at 298 K

Masahito Uchikoshi, Daisuke Akiyama, Ken'ichi Kimijima, Kozo Shinoda

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Abstract

The distribution of metal aqua and chloro complexes is fundamental information for analysis of a chemical reaction involving these complexes. The present study investigated the speciation and structures of chromium aqua and chloro complexes using the thermodynamic model fitting analysis of UV-vis/X-ray absorption spectra. The existence of a negatively charged species was examined by adsorbability of chromium species on a strong base anion exchanger. In the results, a planar square [Cr^III(H₂O)₄]³⁺, a planar square or distorted tetrahedral [Cr^IIICl(H₂O)₃]²⁺, a trigonal bipyramidal [Cr^IIICl₃(H₂O)₂]⁰, and a distorted octahedral [Cr^IIICl₄(H₂O)₂]⁻ were confirmed and the thermodynamic parameters of complexation reactions were quantitatively determined. Investigation of the evolution of speciation of chromium aqua and chloro complexes in a pH 1 solution suggested the existence of [Cr^IIICl₂(H₂O)_m]⁺ (m = 2 or 3) during the hydration process, which diminished in the equilibrium state. The kinetic analysis deserves further investigation to understand the speciation process quantitatively.

Original language	English
Pages (from-to)	32722-32736
Number of pages	15
Journal	RSC Advances
Volume	12
Issue number	50
DOIs	https://doi.org/10.1039/d2ra06279h
Publication status	Published - 2022 Nov 15

ASJC Scopus subject areas

Chemistry(all)
Chemical Engineering(all)

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title = "Speciation of chromium aqua and chloro complexes in hydrochloric acid solutions at 298 K",

abstract = "The distribution of metal aqua and chloro complexes is fundamental information for analysis of a chemical reaction involving these complexes. The present study investigated the speciation and structures of chromium aqua and chloro complexes using the thermodynamic model fitting analysis of UV-vis/X-ray absorption spectra. The existence of a negatively charged species was examined by adsorbability of chromium species on a strong base anion exchanger. In the results, a planar square [CrIII(H2O)4]3+, a planar square or distorted tetrahedral [CrIIICl(H2O)3]2+, a trigonal bipyramidal [CrIIICl3(H2O)2]0, and a distorted octahedral [CrIIICl4(H2O)2]− were confirmed and the thermodynamic parameters of complexation reactions were quantitatively determined. Investigation of the evolution of speciation of chromium aqua and chloro complexes in a pH 1 solution suggested the existence of [CrIIICl2(H2O)m]+ (m = 2 or 3) during the hydration process, which diminished in the equilibrium state. The kinetic analysis deserves further investigation to understand the speciation process quantitatively.",

author = "Masahito Uchikoshi and Daisuke Akiyama and Ken'ichi Kimijima and Kozo Shinoda",

note = "Funding Information: The synchrotron radiation experiments of X-ray absorption spectroscopy were performed at BL-9C of Photon Factory under the approval of the Photon Factory Program Advisory Committee (Proposal No. 2019G127). A part of this work was supported by JSPS KAKENHI Grant Number JP18H01759. Publisher Copyright: {\textcopyright} 2022 The Royal Society of Chemistry.",

year = "2022",

month = nov,

day = "15",

doi = "10.1039/d2ra06279h",

language = "English",

volume = "12",

pages = "32722--32736",

journal = "RSC Advances",

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T1 - Speciation of chromium aqua and chloro complexes in hydrochloric acid solutions at 298 K

AU - Uchikoshi, Masahito

AU - Akiyama, Daisuke

AU - Kimijima, Ken'ichi

AU - Shinoda, Kozo

N1 - Funding Information: The synchrotron radiation experiments of X-ray absorption spectroscopy were performed at BL-9C of Photon Factory under the approval of the Photon Factory Program Advisory Committee (Proposal No. 2019G127). A part of this work was supported by JSPS KAKENHI Grant Number JP18H01759. Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/11/15

Y1 - 2022/11/15

N2 - The distribution of metal aqua and chloro complexes is fundamental information for analysis of a chemical reaction involving these complexes. The present study investigated the speciation and structures of chromium aqua and chloro complexes using the thermodynamic model fitting analysis of UV-vis/X-ray absorption spectra. The existence of a negatively charged species was examined by adsorbability of chromium species on a strong base anion exchanger. In the results, a planar square [CrIII(H2O)4]3+, a planar square or distorted tetrahedral [CrIIICl(H2O)3]2+, a trigonal bipyramidal [CrIIICl3(H2O)2]0, and a distorted octahedral [CrIIICl4(H2O)2]− were confirmed and the thermodynamic parameters of complexation reactions were quantitatively determined. Investigation of the evolution of speciation of chromium aqua and chloro complexes in a pH 1 solution suggested the existence of [CrIIICl2(H2O)m]+ (m = 2 or 3) during the hydration process, which diminished in the equilibrium state. The kinetic analysis deserves further investigation to understand the speciation process quantitatively.

AB - The distribution of metal aqua and chloro complexes is fundamental information for analysis of a chemical reaction involving these complexes. The present study investigated the speciation and structures of chromium aqua and chloro complexes using the thermodynamic model fitting analysis of UV-vis/X-ray absorption spectra. The existence of a negatively charged species was examined by adsorbability of chromium species on a strong base anion exchanger. In the results, a planar square [CrIII(H2O)4]3+, a planar square or distorted tetrahedral [CrIIICl(H2O)3]2+, a trigonal bipyramidal [CrIIICl3(H2O)2]0, and a distorted octahedral [CrIIICl4(H2O)2]− were confirmed and the thermodynamic parameters of complexation reactions were quantitatively determined. Investigation of the evolution of speciation of chromium aqua and chloro complexes in a pH 1 solution suggested the existence of [CrIIICl2(H2O)m]+ (m = 2 or 3) during the hydration process, which diminished in the equilibrium state. The kinetic analysis deserves further investigation to understand the speciation process quantitatively.

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Speciation of chromium aqua and chloro complexes in hydrochloric acid solutions at 298 K

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