Two-Coordinate Iron(I) Complexes on the Edge of Stability: Influence of Dispersion and Steric Effects

Witzke, Ryan J.; Hait, Diptarka; Head‐Gordon, Martin; Tilley, T. Don

doi:10.1021/acs.organomet.1c00218

Cited by 7 publications

(4 citation statements)

References 46 publications

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“…Unfortunately, as shown by H 2 in Figure 1 (and many other species), chemical bond formation/cleavage can be without energy barriers. Additionally, energy based metrics can be affected by nonbonding interactions like dispersion, which may constitute a large proportion of the interaction energy [26,27] …”

Section: Figurementioning

confidence: 99%

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When Is a Bond Broken? The Polarizability Perspective.

Hait,

Head‐Gordon

2023

Angew Chem Int Ed

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The question of when a chemical bond can be said to be broken is of fundamental chemical interest but has not been widely studied. Herein we propose that the maxima of static polarizability along bond dissociation coordinates naturally define cutoff points for bond rupture, as they represent the onset of localization of shared electron density into constituent fragments. Examples of computed polarizability maxima over the course of bond cleavage in main‐group and transition metal compounds are provided, across covalent, dative and charge‐shift bonds. The behavior along reaction paths is also considered. Overall, the static polarizability is found to be a sensitive reporter of electronic structure reorganization associated with bond stretching, and thus can serve as a metric for describing bond cleavage (or diagnose the absence of a chemical bond).

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Section: Figurementioning

confidence: 99%

“…Additionally, energy based metrics can be affected by nonbonding interactions like dispersion, which may constitute a large proportion of the interaction energy. [26,27] An alternative is to focus on the end of electron sharing. Homolytic cleavage in closed-shell molecules results in the separation of bonded electron pairs into independent radical fragments.…”

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When Is a Bond Broken? The Polarizability Perspective.

Hait,

Head‐Gordon

2023

Angew Chem Int Ed

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“…Complexes with two-coordinate, open-shell 3d-metal(I) ions, known for chromium to nickel, are a particular class of compounds in coordination chemistry. − They show interesting single molecule magnetic properties, − and can be used for bond activation, which has focused so far on the metals iron, − cobalt, ,,− and especially nickel. − In contrast, the chemistry of two-coordinate chromium(I) is considerably less developed. This is remarkable as the linear chromium(I) complex [TerCr(PMe 3 )] (Ter = 2,6-Tripp 2 -3,5- i Pr 2 -C 6 H, Tripp = 2,4,6- i Pr 2 -C 6 H 2 ) was the very first example within this class of molecules (Figure A) .…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Properties, and Reactivity of a Linear NHC-Based Chromium(I) Silylamide

et al. 2023

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We describe the synthesis of the linear N-heterocyclic carbene (NHC)-based chromium(I) silylamide [(IMes)Cr(N{Dipp}-Si i Pr 3 )] (IMes = 1,3-dimesityl-imidazol-2-ylidene, Dipp = 2,6-di-isopropylphenyl) via protolytic ligand displacement of the homoleptic chromium(I) silylamide [KCr(N{Dipp}Si i Pr 3 )] with the imidazolium salt IMes•HCl. This could also be extended to the bulkier NHC IDipp (IDipp = 1,3-bis(2,6-di-iso-propylphenyl)imidazol-2-ylidene). Analysis of the magnetic properties of [(IMes)Cr(N{Dipp}Si i Pr 3 )] reveals an isotropic high-spin S = 5/2 state. First reaction studies with this linear chromium(I) complex yields with CO the four-coordinate chromium dicarbonyl complex [(IMes)Cr(CO) 2 (N{Dipp}Si i Pr 3 )], with benzyl bromide oxidation to the trigonal chromium(II) bromide [(IMes)-Cr(Br)(N{Dipp}Si i Pr 3 )], and with DippN 3 the first three-coordinate chromium(III) imide ([(IMes)Cr(NDipp)(N{Dipp}Si i Pr 3 )]).

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“…[14] While the chemistry of this iron amide has been significantly less explored than that of its HMDS congener, it has been found to undergo reduction using KC 8 furnishing potassium Fe(I) ferrate species [15,16] or NHC-stabilized heteroleptic two-coordinate Fe(I) complexes. [17,18] The latter complexes can effectively catalyse cyclotrimerisations of terminal and internal alkynes. [17,19] Recent studies by our group and others have shown that combining iron(II) amides (or alkyls) with a group 1 metal reagent lead to the formation of bimetallic bases (via cocomplexation) capable of promoting FeÀ H exchange reactions of different aromatic substrates.…”

Section: Introductionmentioning

confidence: 99%

Lateral Metallation and Redistribution Reactions of Sodium Ferrates Containing Bulky 2,6‐Diisopropyl‐N‐(trimethylsilyl)anilide Ligands

Maddock

Morton

Kennedy

et al. 2021

Chemistry A European J

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Alkali‐metal ferrates containing amide groups have emerged as regioselective bases capable of promoting Fe−H exchanges of aromatic substrates. Advancing this area of heterobimetallic chemistry, a new series of sodium ferrates is introduced incorporating the bulky arylsilyl amido ligand N(SiMe3)(Dipp) (Dipp=2,6‐iPr2‐C6H3). Influenced by the large steric demands imposed by this amide, transamination of [NaFe(HMDS)3] (HMDS=N(SiMe3)2) with an excess of HN(SiMe3)(Dipp) led to the isolation of heteroleptic [Na(HMDS)2Fe{N(SiMe3)Dipp}]∞ (1) resulting from the exchange of just one HMDS group. An alternative co‐complexation approach, combining the homometallic metal amides [NaN(SiMe3)Dipp] and [Fe{N(SiMe3)Dipp}2] induces lateral metallation of one Me arm from the SiMe3 group in the iron amide furnishing tetrameric [NaFe{N(SiCH2Me2)Dipp}{N(SiMe3)Dipp}]4 (2). Reactivity studies support that this deprotonation is driven by the steric incompatibility of the single metal amides rather than the basic capability of the sodium reagent. Displaying synergistic reactivity, heteroleptic sodium ferrate 1 can selectively promote ferration of pentafluorobenzene using one of its HMDS arms to give heterotrileptic [Na{N(SiMe3)Dipp}(HMDS)Fe(C6F5)]∞ (4). Attempts to deprotonate less activated pyridine led to the isolation of NaHMDS and heteroleptic Fe(II) amide [(py)Fe{N(SiMe3)Dipp}(HMDS)] (5), resulting from an alternative redistribution process which is favoured by the Lewis donor ability of this substrate.

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Two-Coordinate Iron(I) Complexes on the Edge of Stability: Influence of Dispersion and Steric Effects

Cited by 7 publications

References 46 publications

When Is a Bond Broken? The Polarizability Perspective.

When Is a Bond Broken? The Polarizability Perspective.

Synthesis, Properties, and Reactivity of a Linear NHC-Based Chromium(I) Silylamide

Lateral Metallation and Redistribution Reactions of Sodium Ferrates Containing Bulky 2,6‐Diisopropyl‐N‐(trimethylsilyl)anilide Ligands

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