Gas-Phase Study of the Formation and Dissociation of Fe(CO)<sub>4</sub>H<sub>2</sub>:  Kinetics and Bond Dissociation Energies

Wang, Wenhua; Narducci, Amy A.; House, Paul G.; Weitz, Eric

doi:10.1021/ja960252t

Cited by 39 publications

(53 citation statements)

References 25 publications

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“…All adducts Fe(CO) 4 (L) have singlet ground states. As one might expect, gas phase addition of ligands follows second‐order kinetics, first order in the iron fragment and in ligand . However, in solution, the rate of product formation appears not to depend on ligand concentration .…”

Section: Applicationsmentioning

confidence: 86%

“…An example of more quantitative insight concerns the reactivity of iron tetracarbonyl. This unsaturated fragment, with a triplet ground state, is generated by photolysis of iron pentacarbonyl, and the subsequent kinetics of ligand addition to the fragment have been studied both in the gas phase and in solution . All adducts Fe(CO) 4 (L) have singlet ground states.…”

Section: Applicationsmentioning

confidence: 99%

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Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Harvey

2013

WIREs Comput Mol Sci

220

183

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Many chemical reactions involve one or more changes in the total electronic spin of the reacting system as part of one or more elementary steps. Computational and theoretical methods that can be used to understand such reaction steps are described, and a number of recent examples are highlighted. A particularly strong focus is given to general rules that govern multistep reactions of this type. The two most important rules are (1) that spin‐state change without change in atom connectivity, or spin crossover, is facile and rapid, at least when it is exothermic; and (2) that reactions involving spin‐state change and changes in atom connectivity tend to prefer stepwise mechanisms in which spin crossover steps alternate with spin‐allowed bond‐making and breaking steps. WIREs Comput Mol Sci 2014, 4:1–14. doi: 10.1002/wcms.1154 This article is categorized under: Structure and Mechanism > Molecular Structures

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Section: Applicationsmentioning

confidence: 86%

Section: Applicationsmentioning

confidence: 99%

Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Harvey

2013

WIREs Comput Mol Sci

220

183

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“…The H 2 oxidative addition to Fe(CO) 4 has been investigated experimentally 16 and theoretically. 28 The experimental study has shown that the reaction rate is three orders of magnitude slower than the H 2 addition to related electronically unsaturated complexes, a phenomenon tentatively attributed to the spin-forbidden character of the process.…”

Section: 35mentioning

confidence: 99%

“…The relatively high energy of the MECPs in all cases suggests that the rate of addition of H 2 to unsaturated fragments FeL 4 should proceed significantly more slowly than the collisional or diffusion rate, and this has indeed been observed experimentally. Gas-phase addition to Fe(CO) 4 (under high-pressure limiting conditions) 16 is ca. three orders of magnitude slower than is typical for addition of H 2 to other coordinatively unsaturated species, and Fe(dmpe) 2 reacts with dihydrogen roughly 7500 times slower than does Ru(dmpe) 2…”

Section: Minimum Energy Crossing Pointsmentioning

confidence: 99%

Computational study of the spin-forbidden H₂oxidative addition to 16-electron Fe(0) complexes

Harvey

Poli

2003

Dalton Trans.

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The spin-forbidden oxidative addition of H 2 to Fe(CO) 4 , Fe(PH 3 ) 4 , Fe(dpe) 2 and Fe(dmpe) 2 [dpe = H 2 PCH 2 CH 2 PH 2 , dmpe = (CH 3 ) 2 PCH 2 CH 2 P(CH 3 ) 2 ] has been investigated by density functional theory using a modified B3PW91 functional. All 16-electron fragments are found to adopt a spin triplet ground state. The H 2 addition involves a spin crossover in the reagents region of configurational space, at a significantly higher energy relative to the triplet dissociation asymptote and, for the case of Fe(CO) 4 ؒH 2 , even higher than the singlet dissociation asymptote. After crossing to the singlet surface, the addition proceeds directly to the classical cis-dihydride product. Only for the Fe(CO) 4 was it possible to locate a stable energy minimum for the non-classical tautomer (dihydrogen complex), but the energy difference between this minimum and the tautomerisation transition state inverts when taking into account the zero-point energy correction. The geometries at the crossing points indicate a "side-on" approach of the H 2 molecule to the metal for the Fe(CO) 4 , Fe(CO) 2 (PH 3 ) 2 and Fe(PH 3 ) 4 systems. These geometries are more reactants-like for the Fe(CO) 4 system and more product-like for the Fe(PH 3 ) 4 system. The crossing point geometry for the Fe(dpe) 2 system, on the other hand, is nearly C 2 -symmetric. The presence of an energy barrier on going from 3 FeL 4 ϩ H 2 to the crossing point is in agreement with the slow observed rates for addition of H 2 to these unsaturated organometallic fragments.

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“…on the gas-phase reactivity of spin triplet Fe(CO) 4 should also be underlined [36][37][38]. We emphasize in this article, however, that spin crossover reactivity is a common phenomenon also for reactions of commonly available organometallic compounds in solution.…”

Section: Spin Crossover Reactions: the Forbiddenness Factormentioning

confidence: 93%

Open shell organometallics: a general analysis of their electronic structure and reactivity

Poli

2004

Journal of Organometallic Chemistry

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Transition metal organometallic compounds that contain fewer than 18-electrons and two or more unpaired electrons are generally excluded from treatises of either Werner-type coordination compounds or organometallic chemistry. However, they can be seen as the bridge filling the gap between these two traditional areas of coordination chemistry. Their magnetic and optical properties are reminiscent of the Werner-type complexes, whereas their chemical reactivity parallels that of the lower-valent organometallics. Spin state change phenomena are of paramount importance in this area. This paper provides a broad perspective of this area, with particular attention to: (i) how the ground state properties can be related to the metal and ligands nature; (ii) under which circumstances the often inappropriately invoked concept of ''spin block'' is meaningful; (iii) the spin acceleration concept; (iv) how the coordination sphere affects the topology of the reaction coordinate in the vicinity of spin crossing points; and (v) the effect of spin state changes on reaction selectivities.

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Gas-Phase Study of the Formation and Dissociation of Fe(CO)₄H₂: Kinetics and Bond Dissociation Energies

Cited by 39 publications

References 25 publications

Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Computational study of the spin-forbidden H₂oxidative addition to 16-electron Fe(0) complexes

Open shell organometallics: a general analysis of their electronic structure and reactivity

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Gas-Phase Study of the Formation and Dissociation of Fe(CO)4H2: Kinetics and Bond Dissociation Energies

Cited by 39 publications

References 25 publications

Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Spin‐forbidden reactions: computational insight into mechanisms and kinetics

Computational study of the spin-forbidden H2oxidative addition to 16-electron Fe(0) complexes

Open shell organometallics: a general analysis of their electronic structure and reactivity

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Gas-Phase Study of the Formation and Dissociation of Fe(CO)₄H₂: Kinetics and Bond Dissociation Energies

Computational study of the spin-forbidden H₂oxidative addition to 16-electron Fe(0) complexes