Substitution of methanol-d4 for the coordinated water in the trinuclear complexes, [M33-O)(μ-CH3COO)6(H2O)3]+ (M3=Ru3, Rh3 or Ru2Rh) in methanol-d4

Yoichi Sasaki, Akira Nagasawa, Ayako Yamamoto, Tasuko Ito

Research output: Contribution to journalArticle

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Abstract

The 1H NMR spectra of acetate methyl signals of the titled three complexes in CD3OD change with time due to successive substitution of CD3OD for the coordinated water molecules. The first-order rate constants for the first methanol-d4 substitution of the triruthenium(III) and trirhodium(III) complexes are 7.7×10-4 s-1 (298.2 K) (ΔH‡,=103±6 kJ mol-1 and ΔS‡=+41±12 J K-1 mol-1 at 0-21 °C) and 1.3×10-3 s-1 (298.2 K) (ΔH‡=102±9 kJ mol-1 and ΔS‡=+42±32 J K-1 mol-1 at 0-10 °C) per one metal ion, respectively, which are greater by approximately 2 and 6 orders of magnitude, respectively, than the water exchange reactions of the hexaaqua complexes of these metal ions. The trans effect of the central oxide ion is considered as a major factor responsible for the labilization. The first-order rate constants for the mixed-metal rhodium-diruthenium complex at 298.2 K are 9.9×10-5 (ΔH‡=109±4 kJ mol-1 and ΔS‡=+44±9 J K-1 mol-1) and 7.9×10-5 s-1 (ΔH‡=103±3 kJ mol-1 and ΔS‡=+22±6 J K-1 mol-1 at 10.1-35.3 °C) at ruthenium and rhodium centers, respectively, which are c. 10 times smaller than the corresponding values for the homonuclear complexes. The slower rates in the mixed-metal complex indicate that electronic configuration in the molecular orbital based on (metal-dπ)-(oxygen-pπ) interactions plays some role in controlling the substitution rate. On the basis of the activation parameters, a dissociative mechanism is proposed for all these reactions.

Original languageEnglish
Pages (from-to)175-182
Number of pages8
JournalInorganica Chimica Acta
Volume212
Issue number1-2
DOIs
Publication statusPublished - 1993
Externally publishedYes

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Methanol
Rhodium
Substitution reactions
methyl alcohol
substitutes
Metal ions
Water
Rate constants
Metals
rhodium
water
metal ions
Ruthenium
Coordination Complexes
Molecular orbitals
metals
Metal complexes
Oxides
Ion exchange
Chemical activation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Substitution of methanol-d4 for the coordinated water in the trinuclear complexes, [M33-O)(μ-CH3COO)6(H2O)3]+ (M3=Ru3, Rh3 or Ru2Rh) in methanol-d4 . / Sasaki, Yoichi; Nagasawa, Akira; Yamamoto, Ayako; Ito, Tasuko.

In: Inorganica Chimica Acta, Vol. 212, No. 1-2, 1993, p. 175-182.

Research output: Contribution to journalArticle

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title = "Substitution of methanol-d4 for the coordinated water in the trinuclear complexes, [M3(μ3-O)(μ-CH3COO)6(H2O)3]+ (M3=Ru3, Rh3 or Ru2Rh) in methanol-d4",
abstract = "The 1H NMR spectra of acetate methyl signals of the titled three complexes in CD3OD change with time due to successive substitution of CD3OD for the coordinated water molecules. The first-order rate constants for the first methanol-d4 substitution of the triruthenium(III) and trirhodium(III) complexes are 7.7×10-4 s-1 (298.2 K) (ΔH‡,=103±6 kJ mol-1 and ΔS‡=+41±12 J K-1 mol-1 at 0-21 °C) and 1.3×10-3 s-1 (298.2 K) (ΔH‡=102±9 kJ mol-1 and ΔS‡=+42±32 J K-1 mol-1 at 0-10 °C) per one metal ion, respectively, which are greater by approximately 2 and 6 orders of magnitude, respectively, than the water exchange reactions of the hexaaqua complexes of these metal ions. The trans effect of the central oxide ion is considered as a major factor responsible for the labilization. The first-order rate constants for the mixed-metal rhodium-diruthenium complex at 298.2 K are 9.9×10-5 (ΔH‡=109±4 kJ mol-1 and ΔS‡=+44±9 J K-1 mol-1) and 7.9×10-5 s-1 (ΔH‡=103±3 kJ mol-1 and ΔS‡=+22±6 J K-1 mol-1 at 10.1-35.3 °C) at ruthenium and rhodium centers, respectively, which are c. 10 times smaller than the corresponding values for the homonuclear complexes. The slower rates in the mixed-metal complex indicate that electronic configuration in the molecular orbital based on (metal-dπ)-(oxygen-pπ) interactions plays some role in controlling the substitution rate. On the basis of the activation parameters, a dissociative mechanism is proposed for all these reactions.",
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T1 - Substitution of methanol-d4 for the coordinated water in the trinuclear complexes, [M3(μ3-O)(μ-CH3COO)6(H2O)3]+ (M3=Ru3, Rh3 or Ru2Rh) in methanol-d4

AU - Sasaki, Yoichi

AU - Nagasawa, Akira

AU - Yamamoto, Ayako

AU - Ito, Tasuko

PY - 1993

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N2 - The 1H NMR spectra of acetate methyl signals of the titled three complexes in CD3OD change with time due to successive substitution of CD3OD for the coordinated water molecules. The first-order rate constants for the first methanol-d4 substitution of the triruthenium(III) and trirhodium(III) complexes are 7.7×10-4 s-1 (298.2 K) (ΔH‡,=103±6 kJ mol-1 and ΔS‡=+41±12 J K-1 mol-1 at 0-21 °C) and 1.3×10-3 s-1 (298.2 K) (ΔH‡=102±9 kJ mol-1 and ΔS‡=+42±32 J K-1 mol-1 at 0-10 °C) per one metal ion, respectively, which are greater by approximately 2 and 6 orders of magnitude, respectively, than the water exchange reactions of the hexaaqua complexes of these metal ions. The trans effect of the central oxide ion is considered as a major factor responsible for the labilization. The first-order rate constants for the mixed-metal rhodium-diruthenium complex at 298.2 K are 9.9×10-5 (ΔH‡=109±4 kJ mol-1 and ΔS‡=+44±9 J K-1 mol-1) and 7.9×10-5 s-1 (ΔH‡=103±3 kJ mol-1 and ΔS‡=+22±6 J K-1 mol-1 at 10.1-35.3 °C) at ruthenium and rhodium centers, respectively, which are c. 10 times smaller than the corresponding values for the homonuclear complexes. The slower rates in the mixed-metal complex indicate that electronic configuration in the molecular orbital based on (metal-dπ)-(oxygen-pπ) interactions plays some role in controlling the substitution rate. On the basis of the activation parameters, a dissociative mechanism is proposed for all these reactions.

AB - The 1H NMR spectra of acetate methyl signals of the titled three complexes in CD3OD change with time due to successive substitution of CD3OD for the coordinated water molecules. The first-order rate constants for the first methanol-d4 substitution of the triruthenium(III) and trirhodium(III) complexes are 7.7×10-4 s-1 (298.2 K) (ΔH‡,=103±6 kJ mol-1 and ΔS‡=+41±12 J K-1 mol-1 at 0-21 °C) and 1.3×10-3 s-1 (298.2 K) (ΔH‡=102±9 kJ mol-1 and ΔS‡=+42±32 J K-1 mol-1 at 0-10 °C) per one metal ion, respectively, which are greater by approximately 2 and 6 orders of magnitude, respectively, than the water exchange reactions of the hexaaqua complexes of these metal ions. The trans effect of the central oxide ion is considered as a major factor responsible for the labilization. The first-order rate constants for the mixed-metal rhodium-diruthenium complex at 298.2 K are 9.9×10-5 (ΔH‡=109±4 kJ mol-1 and ΔS‡=+44±9 J K-1 mol-1) and 7.9×10-5 s-1 (ΔH‡=103±3 kJ mol-1 and ΔS‡=+22±6 J K-1 mol-1 at 10.1-35.3 °C) at ruthenium and rhodium centers, respectively, which are c. 10 times smaller than the corresponding values for the homonuclear complexes. The slower rates in the mixed-metal complex indicate that electronic configuration in the molecular orbital based on (metal-dπ)-(oxygen-pπ) interactions plays some role in controlling the substitution rate. On the basis of the activation parameters, a dissociative mechanism is proposed for all these reactions.

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