Rates of Water Exchange in 2,2′-Bipyridine and 1,10-Phenanthroline Complexes of CoII and MnII

Shravan S. Acharya; Bjorn Winther Jensen; Leone Spiccia; C. André Ohlin

doi:10.1071/CH16667

Rates of Water Exchange in 2,2′-Bipyridine and 1,10-Phenanthroline Complexes of Co^II and Mn^II

Shravan S. Acharya, Bjorn Winther Jensen, Leone Spiccia, C. André Ohlin^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four Co^II complexes and one Mn^II complex: [Co(bpy)(H₂O)₄]²⁺, [Co(bpy)₂ (H₂O)₂]²⁺, [Co(phen)-(H₂O)₄]²⁺, [Co(phen)₂ (H₂O)₂]²⁺, and [Mn(bpy)(H₂O)₄]²⁺ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k²⁹⁸ (1.8±0.1)×107s-1 for [Mn(H₂O)₆]²⁺ to (7.2±0.3)×107 s^-1 for [Mn(phen)₂ (H₂O)₂]²⁺, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M-OH₂ distance and degree of substitution.

Original language	English
Pages (from-to)	751-754
Number of pages	4
Journal	Australian Journal of Chemistry
Volume	70
Issue number	6
DOIs	https://doi.org/10.1071/CH16667
Publication status	Published - 2017

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Chemistry(all)

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@article{861c00c92b6e46df9d697156e18fe751,

title = "Rates of Water Exchange in 2,2′-Bipyridine and 1,10-Phenanthroline Complexes of CoII and MnII ",

abstract = "The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8±0.1)×107s-1 for [Mn(H2O)6]2+ to (7.2±0.3)×107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M-OH2 distance and degree of substitution.",

author = "Acharya, {Shravan S.} and {Winther Jensen}, Bjorn and Leone Spiccia and Ohlin, {C. Andr{\'e}}",

year = "2017",

doi = "10.1071/CH16667",

language = "English",

volume = "70",

pages = "751--754",

journal = "Australian Journal of Chemistry",

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T1 - Rates of Water Exchange in 2,2′-Bipyridine and 1,10-Phenanthroline Complexes of CoII and MnII

AU - Acharya, Shravan S.

AU - Winther Jensen, Bjorn

AU - Spiccia, Leone

AU - Ohlin, C. André

PY - 2017

Y1 - 2017

N2 - The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8±0.1)×107s-1 for [Mn(H2O)6]2+ to (7.2±0.3)×107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M-OH2 distance and degree of substitution.

AB - The rates and activation parameters of water exchange at pH 3.0 have been determined using variable temperature 17O NMR spectroscopy for four CoII complexes and one MnII complex: [Co(bpy)(H2O)4]2+, [Co(bpy)2 (H2O)2]2+, [Co(phen)-(H2O)4]2+, [Co(phen)2 (H2O)2]2+, and [Mn(bpy)(H2O)4]2+ (bpy = 2,2′-bipyridyl and phen = 1,10-phenanthroline). Substitution of aquo ligands with 1,10-phenanthroline or 2,2′-bipyridyl leads to an increase in the rate of exchange in the manganese complexes, from k298 (1.8±0.1)×107s-1 for [Mn(H2O)6]2+ to (7.2±0.3)×107 s-1 for [Mn(phen)2 (H2O)2]2+, whereas the trends are more complex for the cobalt complexes. We have used the new data in conjunction with literature data for similar complexes to analyse the effect of M-OH2 distance and degree of substitution.

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Rates of Water Exchange in 2,2′-Bipyridine and 1,10-Phenanthroline Complexes of Co^II and Mn^II

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