A dichromium(II) bis(η8-pentalene) double-sandwich complex with a spin equilibrium: Synthetic, structural, magnetic, and theoretical studies

Gabor Balazs; F. Geoffrey N. Cloke; Laura Gagliardi; Jennifer C. Green; Andrew Harrison; Peter B. Hitchcock; Abdul Rehaman Moughal Shahi; Owen T. Summerscales

doi:10.1021/om701153t

A dichromium(II) bis(η⁸-pentalene) double-sandwich complex with a spin equilibrium: Synthetic, structural, magnetic, and theoretical studies

Gabor Balazs, F. Geoffrey N. Cloke, Laura Gagliardi, Jennifer C. Green, Andrew Harrison, Peter B. Hitchcock, Abdul Rehaman Moughal Shahi, Owen T. Summerscales

Chemistry (Twin Cities)

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Abstract

The new bis(pentalene) complex Cr₂(η⁵: η⁵-C₈H₄ ^1,4SiiPr ₃)₂ has been synthesized and characterized; it is found to exhibit paramagnetism at room temperature, and solid-state magnetic studies show that the dimer is best modeled as containing a pair of antiferromagnetically interacting S = 1/2 centers with the separation between the singlet ground state and triplet excited state being 2.23 kJ mol ^-1. Structural data show a Cr - Cr distance of 2.2514(15) Å, consistent with a strong metal-metal interaction. The bonding has been further investigated by density functional, hybrid, and CASPT2 methods. The metal-metal interaction is best described by a double bond with each metal having an 18-electron count. Theory predicts the singlet and triplet states to lie close in energy but puts the triplet state at a slightly lower energy than the singlet. The energy difference predicted by CASPT2 is closest to the experimental value.

Original language	English (US)
Pages (from-to)	2013-2020
Number of pages	8
Journal	Organometallics
Volume	27
Issue number	9
DOIs	https://doi.org/10.1021/om701153t
State	Published - May 12 2008

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title = "A dichromium(II) bis(η8-pentalene) double-sandwich complex with a spin equilibrium: Synthetic, structural, magnetic, and theoretical studies",

abstract = "The new bis(pentalene) complex Cr2(η5: η5-C8H4 1,4SiiPr 3)2 has been synthesized and characterized; it is found to exhibit paramagnetism at room temperature, and solid-state magnetic studies show that the dimer is best modeled as containing a pair of antiferromagnetically interacting S = 1/2 centers with the separation between the singlet ground state and triplet excited state being 2.23 kJ mol -1. Structural data show a Cr - Cr distance of 2.2514(15) {\AA}, consistent with a strong metal-metal interaction. The bonding has been further investigated by density functional, hybrid, and CASPT2 methods. The metal-metal interaction is best described by a double bond with each metal having an 18-electron count. Theory predicts the singlet and triplet states to lie close in energy but puts the triplet state at a slightly lower energy than the singlet. The energy difference predicted by CASPT2 is closest to the experimental value.",

author = "Gabor Balazs and Cloke, {F. Geoffrey N.} and Laura Gagliardi and Green, {Jennifer C.} and Andrew Harrison and Hitchcock, {Peter B.} and Shahi, {Abdul Rehaman Moughal} and Summerscales, {Owen T.}",

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T2 - Synthetic, structural, magnetic, and theoretical studies

AU - Balazs, Gabor

AU - Cloke, F. Geoffrey N.

AU - Gagliardi, Laura

AU - Green, Jennifer C.

AU - Harrison, Andrew

AU - Hitchcock, Peter B.

AU - Shahi, Abdul Rehaman Moughal

AU - Summerscales, Owen T.

PY - 2008/5/12

Y1 - 2008/5/12

N2 - The new bis(pentalene) complex Cr2(η5: η5-C8H4 1,4SiiPr 3)2 has been synthesized and characterized; it is found to exhibit paramagnetism at room temperature, and solid-state magnetic studies show that the dimer is best modeled as containing a pair of antiferromagnetically interacting S = 1/2 centers with the separation between the singlet ground state and triplet excited state being 2.23 kJ mol -1. Structural data show a Cr - Cr distance of 2.2514(15) Å, consistent with a strong metal-metal interaction. The bonding has been further investigated by density functional, hybrid, and CASPT2 methods. The metal-metal interaction is best described by a double bond with each metal having an 18-electron count. Theory predicts the singlet and triplet states to lie close in energy but puts the triplet state at a slightly lower energy than the singlet. The energy difference predicted by CASPT2 is closest to the experimental value.

AB - The new bis(pentalene) complex Cr2(η5: η5-C8H4 1,4SiiPr 3)2 has been synthesized and characterized; it is found to exhibit paramagnetism at room temperature, and solid-state magnetic studies show that the dimer is best modeled as containing a pair of antiferromagnetically interacting S = 1/2 centers with the separation between the singlet ground state and triplet excited state being 2.23 kJ mol -1. Structural data show a Cr - Cr distance of 2.2514(15) Å, consistent with a strong metal-metal interaction. The bonding has been further investigated by density functional, hybrid, and CASPT2 methods. The metal-metal interaction is best described by a double bond with each metal having an 18-electron count. Theory predicts the singlet and triplet states to lie close in energy but puts the triplet state at a slightly lower energy than the singlet. The energy difference predicted by CASPT2 is closest to the experimental value.

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A dichromium(II) bis(η⁸-pentalene) double-sandwich complex with a spin equilibrium: Synthetic, structural, magnetic, and theoretical studies

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