On the mechanism of dioxygen formation from a di-μ-oxo-bridged manganese dinuclear complex

Simon Petrie; Robert Stranger

doi:10.1021/ic049967k

On the mechanism of dioxygen formation from a di-μ-oxo-bridged manganese dinuclear complex

Simon Petrie, Robert Stranger^*

^*Corresponding author for this work

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

8 Citations (Scopus)

Abstract

Density functional theory (DFT) calculations, using the Becke-Perdew gradient-corrected functional with a triple-ζ-plus-polarization basis set, have been used to characterize the [(H₂O)(H₃N) ₃Mn(μ-O)₂Mn(NH₃)₃(OH ₂)]^q+ (q = 2-5) complexes. This structure has been proposed as a possible model for the oxygen-releasing site of the photosystem II (PSII) reaction center. We have performed full optimizations to locate stationary points in various spin states for each of the +2 to +5 charge states. Our calculations indicate that O₂ release from the vacuum-phase +5 charge state complex is barrier inhibited, in contrast to the results of a recent DFT study. We report several new di-μ-oxo-bridged stationary points with spin multiplicities of S = 1/2, 3/2, and 5/2 and effective metal oxidation states of Mn^IVMn^V for the +5 charge state. Finally, calculations employing the 'conductorlike screening model' (COSMO), to address the inclusion of solvent effects, indicate that dissociative O₂ release from the +5 charge state model complex is inhibited by a major barrier and is therefore apparently highly disfavored.

Original language	English
Pages (from-to)	5237-5244
Number of pages	8
Journal	Inorganic Chemistry
Volume	43
Issue number	17
DOIs	https://doi.org/10.1021/ic049967k
Publication status	Published - 23 Aug 2004

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title = "On the mechanism of dioxygen formation from a di-μ-oxo-bridged manganese dinuclear complex",

abstract = "Density functional theory (DFT) calculations, using the Becke-Perdew gradient-corrected functional with a triple-ζ-plus-polarization basis set, have been used to characterize the [(H2O)(H3N) 3Mn(μ-O)2Mn(NH3)3(OH 2)]q+ (q = 2-5) complexes. This structure has been proposed as a possible model for the oxygen-releasing site of the photosystem II (PSII) reaction center. We have performed full optimizations to locate stationary points in various spin states for each of the +2 to +5 charge states. Our calculations indicate that O2 release from the vacuum-phase +5 charge state complex is barrier inhibited, in contrast to the results of a recent DFT study. We report several new di-μ-oxo-bridged stationary points with spin multiplicities of S = 1/2, 3/2, and 5/2 and effective metal oxidation states of MnIVMnV for the +5 charge state. Finally, calculations employing the 'conductorlike screening model' (COSMO), to address the inclusion of solvent effects, indicate that dissociative O2 release from the +5 charge state model complex is inhibited by a major barrier and is therefore apparently highly disfavored.",

author = "Simon Petrie and Robert Stranger",

year = "2004",

month = aug,

day = "23",

doi = "10.1021/ic049967k",

language = "English",

volume = "43",

pages = "5237--5244",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "17",

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TY - JOUR

T1 - On the mechanism of dioxygen formation from a di-μ-oxo-bridged manganese dinuclear complex

AU - Petrie, Simon

AU - Stranger, Robert

PY - 2004/8/23

Y1 - 2004/8/23

N2 - Density functional theory (DFT) calculations, using the Becke-Perdew gradient-corrected functional with a triple-ζ-plus-polarization basis set, have been used to characterize the [(H2O)(H3N) 3Mn(μ-O)2Mn(NH3)3(OH 2)]q+ (q = 2-5) complexes. This structure has been proposed as a possible model for the oxygen-releasing site of the photosystem II (PSII) reaction center. We have performed full optimizations to locate stationary points in various spin states for each of the +2 to +5 charge states. Our calculations indicate that O2 release from the vacuum-phase +5 charge state complex is barrier inhibited, in contrast to the results of a recent DFT study. We report several new di-μ-oxo-bridged stationary points with spin multiplicities of S = 1/2, 3/2, and 5/2 and effective metal oxidation states of MnIVMnV for the +5 charge state. Finally, calculations employing the 'conductorlike screening model' (COSMO), to address the inclusion of solvent effects, indicate that dissociative O2 release from the +5 charge state model complex is inhibited by a major barrier and is therefore apparently highly disfavored.

AB - Density functional theory (DFT) calculations, using the Becke-Perdew gradient-corrected functional with a triple-ζ-plus-polarization basis set, have been used to characterize the [(H2O)(H3N) 3Mn(μ-O)2Mn(NH3)3(OH 2)]q+ (q = 2-5) complexes. This structure has been proposed as a possible model for the oxygen-releasing site of the photosystem II (PSII) reaction center. We have performed full optimizations to locate stationary points in various spin states for each of the +2 to +5 charge states. Our calculations indicate that O2 release from the vacuum-phase +5 charge state complex is barrier inhibited, in contrast to the results of a recent DFT study. We report several new di-μ-oxo-bridged stationary points with spin multiplicities of S = 1/2, 3/2, and 5/2 and effective metal oxidation states of MnIVMnV for the +5 charge state. Finally, calculations employing the 'conductorlike screening model' (COSMO), to address the inclusion of solvent effects, indicate that dissociative O2 release from the +5 charge state model complex is inhibited by a major barrier and is therefore apparently highly disfavored.

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U2 - 10.1021/ic049967k

DO - 10.1021/ic049967k

M3 - Article

SN - 0020-1669

VL - 43

SP - 5237

EP - 5244

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 17

ER -

On the mechanism of dioxygen formation from a di-μ-oxo-bridged manganese dinuclear complex

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