Experiments on the HOMO‐LUMO Nature of Metal‐Metal Bonds

Beurich, Harald; Madach, Thomas; Richter, Felix; Vahrenkamp, Heinrich

doi:10.1002/anie.197906901

Cited by 33 publications

(13 citation statements)

References 8 publications

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“…The cobalt hyperfine splittings are consistent with those reported by others for 49 e - trinuclear systems of related structure. − For example, A ∥ (Co) values of 66−76 G have been reported for the isoelectronic systems (μ 3 -S)Co 3 (CO) 9 , [(μ 3 -S)FeCo 2 (CO) 9 ] - , and [(μ 3 -CPh)Co 3 (CO) 9 ] - . The related doubly capped system [(μ 3 -CPh) 2 Co 3 Cp 3 ] - has A ∥ = 83 G …”

Section: Resultssupporting

confidence: 89%

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

1998

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Oxidations and reductions of a series of 48-electron (e-) metal clusters containing a tricobalt core have been investigated by voltammetry, electrolysis, IR spectroelectrochemistry, and EPR spectroscopy. Three isomers of Cp3Co3(CO)3 have been studied. The all-CO-bridging isomer C 3 v Cp3Co3(μ-CO)3 (1B) is stable in the 48 e- and 49 e- forms, but the 47 e- cation isomerizes to a doubly-CO-bridging structure 1T +. The other two isomers, Cp3Co3(μ3-CO)(μ-CO)2 (1F) and Cp3Co3(μ-CO)2(CO) (1T), are present in about a 1:1 ratio near room temperature, but their solutions show only Nernstian 1 e- cyclic voltammetry (CV) responses. IR spectroelectrochemistry and analysis of the E 1/2 values show that the deceptively simple CV responses arise from a rapid equilibration between isomers 1F and 1T, rather than from a lack of structural change accompanying charge transfer. The cluster Cp*2Cp‘Co3(μ3-CO)(μ-CO)2 (3) (Cp* = C5Me5, Cp‘ = C5MeH4) is shown to retain its isomeric identity through three cluster oxidation states, most likely owing to a steric preference for a face-bridging carbonyl ligand in the ring-substituted complex. The 49 e- anions of the tricobalt complexes display EPR spectra consistent with a SOMO which is antibonding in the trimetallic plane. Additional regular hyperfine features in glassy matrices at 77 K are assigned to dimers consisting of a 49 e- anion magnetically coupled to either a 48 e- neutral precursor or another 49 e- anion.

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Section: Resultssupporting

confidence: 89%

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

1998

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“…As in FeCo 2 (μ 3 -PPh)(CO) 9 , the phosphorus atom of the μ 3 -phosphinidene ligand caps symmetrically the trimetal plane with an average RC−P(1) bond distance of 2.176 Å which is significantly shorter than the Co−P or Ru−P bond distances in cluster 4b . As expected, the μ 3 -P(1)−C(10) distance of 1.836(4) Å is slightly shorter than the μ 4 -P−C(14) distance in 4b and is comparable to those observed in other μ 3 -PR ligands. 6b, Cluster 5b has 6 electron pairs, consistent with an arachno trigonal bipyramid for the three metal atoms or a nido trigonal bipyramid when the P atom is considered as part of the skeleton. As in 4b , the metal atoms all obey the 18-electron rule.…”

Section: Resultsmentioning

confidence: 95%

Metallosite Selectivity Studies in Reactions of Tetrahedral MCo₃ Carbonyl Clusters (M = Fe, Ru) with Cyclohexylphosphine. Skeletal Rearrangements Leading to Tri- and Pentanuclear Phosphinidene Clusters and Crystal Structures of RuCo₄(μ₄-PCy)(μ-CO)₂(CO)₁₁ and RuCo₂(μ₃-PCy)(CO)₉

et al. 1999

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We have studied the metallosite selectivity of substitution reactions at heterometallic tetranuclear clusters of the type HMCo3(CO)12 (M = Fe, Ru). Monosubstitution with PCyH2 occurs with a different metalloselectivity as a function of M. When M = Fe, substitution of a Co-bound CO ligand occurs whereas when M = Ru, the phosphine ligand is bound to Ru. Introduction of a second substituent (PCyH2 or NMe3) occurs in both cases at cobalt and, in the case of HFeCo3(CO)11(PCyH2), at a cobalt that does not carry the PCyH2 substituent. The clusters HMCo3(CO)11(PCyH2) (2a, M = Fe; 2b, M = Ru) transform in solution to give the corresponding μ3-phosphinidene-capped heterotrinuclear clusters MCo2(μ3-PCy)(CO)9 (4a, M = Fe; 4b, M = Ru). The μ4-phosphinidene-capped intermediate RuCo4(μ4-PCy)(μ-CO)2(CO)11 (5b) could be fully characterized, whereas the analogous species could not be isolated when M = Fe. The transformation of 2a,b was accelerated by addition of Me3NO. This work demonstrates that a reaction which represents a partial cluster fragmentation, with a nuclearity change from 4 to 3, may occur via the intermediacy of a larger cluster, of nuclearity 5. Reactions and products were studied by IR and 1H, 31P{1H}, and 59Co NMR spectroscopic methods, and the clusters 4b and 5b have been characterized by X-ray diffraction.

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“…The features thus retained clearly indicated that only a subset of the initially considered features are actually influential in describing the formability and stability of the oxide perovskite. These include atom-specific featuresthe highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, ionization energy, electronegativity, Zunger’s pseudopotential radius (sum of the radii for the s and p orbitals), and electron affinityand geometric features of the compoundthe tolerance factor ( t ), octahedral factor (μ), and mismatch factor (μ̅ B ). Since we include compounds with two cations in the A-as well as the B-sites, we also introduce an additional mismatch factor for the A-site: μ̅ A = | r A – r A ′ |/2 r X .…”

Section: Inputs and Methodsmentioning

confidence: 99%

A Machine Learning Approach for the Prediction of Formability and Thermodynamic Stability of Single and Double Perovskite Oxides

et al. 2021

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Perovskite oxides continue to attract huge interest due to their fascinating and wide-ranging properties for diverse applications. The tunability of these properties may be further enhanced by increasing their compositional complexity via double perovskite-ordered configurations containing multiple cations. In this work, we focus on an exhaustive chemical space of single and double oxide perovskites and optimally explore this space to identify novel compositions that are likely to form stable compounds. Critically, we examine the relationship between formability, the practical ability to synthesize a compound, and stability, the thermodynamic preference to form the structure. Our formability and stability training data sets were enumerated from the available experimental literature and in-house density functional theory computations and contained 1505 and 3469 examples, respectively, representing state-of-the-art in the current open literature in perovskite and double perovskite compounds. Subsequently, cross-validated and highly accurate machine learning classification models are built using these training data sets and employed to screen for novel stable oxide perovskites. The study identifies (1) atomic features relevant to prediction of formability and stability in perovskite and double perovskite compounds, (2) the importance of including energy contributions due to local structural relaxations going beyond the high symmetry perovskite phase, and (3) 437,828 double perovskite compounds that are likely to be stable and 891,188 compounds that are likely to be formable. From the intersection of this large chemical space of formable and stable oxide perovskites, 414 compositions are identified as the most promising candidates for future experimental synthesis of novel oxide perovskites. The developed models may be generalized and have implications beyond perovskite discovery if applied to other families of compounds.

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Experiments on the HOMO‐LUMO Nature of Metal‐Metal Bonds

Abstract: formed as main product. This reaction course and the strongly exothermic reaction with lactones indicate that iodotrimethylsilane is considerably more reactive than bromotrimethylsilane.

Cited by 33 publications

References 8 publications

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

Metallosite Selectivity Studies in Reactions of Tetrahedral MCo₃ Carbonyl Clusters (M = Fe, Ru) with Cyclohexylphosphine. Skeletal Rearrangements Leading to Tri- and Pentanuclear Phosphinidene Clusters and Crystal Structures of RuCo₄(μ₄-PCy)(μ-CO)₂(CO)₁₁ and RuCo₂(μ₃-PCy)(CO)₉

A Machine Learning Approach for the Prediction of Formability and Thermodynamic Stability of Single and Double Perovskite Oxides

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Experiments on the HOMO‐LUMO Nature of Metal‐Metal Bonds

Abstract: formed as main product. This reaction course and the strongly exothermic reaction with lactones indicate that iodotrimethylsilane is considerably more reactive than bromotrimethylsilane.

Cited by 33 publications

References 8 publications

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

Geometric Preferences of Tricobalt Clusters Having 47−49 Valence Electron Counts: Deceptively Simple Cyclic Voltammetric Responses and EPR Evidence for Exchange-Coupled Dimers in Frozen Solutions

Metallosite Selectivity Studies in Reactions of Tetrahedral MCo3 Carbonyl Clusters (M = Fe, Ru) with Cyclohexylphosphine. Skeletal Rearrangements Leading to Tri- and Pentanuclear Phosphinidene Clusters and Crystal Structures of RuCo4(μ4-PCy)(μ-CO)2(CO)11 and RuCo2(μ3-PCy)(CO)9

A Machine Learning Approach for the Prediction of Formability and Thermodynamic Stability of Single and Double Perovskite Oxides

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Product

Resources

About

Metallosite Selectivity Studies in Reactions of Tetrahedral MCo₃ Carbonyl Clusters (M = Fe, Ru) with Cyclohexylphosphine. Skeletal Rearrangements Leading to Tri- and Pentanuclear Phosphinidene Clusters and Crystal Structures of RuCo₄(μ₄-PCy)(μ-CO)₂(CO)₁₁ and RuCo₂(μ₃-PCy)(CO)₉