Inverted ligand field theory

Last updated
Ligand field molecular orbital (MO) bonding regimes for Werner-type (left), covalent (middle), and inverted ligand fields. MO diagrams ligand field.png
Ligand field molecular orbital (MO) bonding regimes for Werner-type (left), covalent (middle), and inverted ligand fields.
At the transition-metal - main group boundary, metal cations in organometallic complexes are more electronegative than the relatively more electropositive ligand atoms which act as z-type ligands. TM-MG boundary.png
At the transition-metal - main group boundary, metal cations in organometallic complexes are more electronegative than the relatively more electropositive ligand atoms which act as z-type ligands.

Inverted ligand field theory (ILFT) describes a phenomenon in the bonding of coordination complexes where the lowest unoccupied molecular orbital is primarily of ligand character. [2] [1] This is contrary to the traditional ligand field theory or crystal field theory picture and arises from the breaking down of the assumption that in organometallic complexes, ligands are more electronegative and have frontier orbitals below those of the d orbitals of electropositive metals. [3] [4] As we move to the right of the d-block and approach the transition-metal - main group boundary, the d orbitals become more core-like, making their cations more electronegative. This decreases their energies and eventually arrives at a point where they are lower in energy than the ligand frontier orbitals. [2] Here the ligand field inverts so that the bonding orbitals are more metal-based, and antibonding orbitals more ligand-based. The relative arrangement of the d orbitals are also inverted in complexes displaying this inverted ligand field. [2] This has consequences in our understanding of accessible metal oxidation states, and the reactivity of complexes exhibiting ILFT.

Contents

History

Cu(CF3)4 square planar structure Cu-CF3-4-1.gif
Cu(CF3)4 square planar structure

The first example of an inverted ligand field was demonstrated in paper form 1995 by James Snyder. [5] In this theoretical paper, Snyder proposed that the [Cu(CF3)4]- complexes reported by Naumann et al. and assigned a formal oxidation state of 3+ at the copper [6] would be better thought of as Cu(I). By comparing the d-orbital occupation, calculated charges and orbital population of [Cu(CF3)4]- "Cu(III)" complex and the formally Cu(I) [Cu(CH3)2]- complex, they illustrated how the former could be better described as a d10 copper complex experiencing two electron donation from the CF3- ligands. [5] The phenomenon, termed an inverted ligand field by Roald Hoffman, began to be described by Aullón and Alvarez as they identified this phenonmenon as being a result of relative electronegativities. [7] Lancaster and co-workers later provided experimental evidence to support the assignment of this oxidation state. Using UV/visible/near IR spectroscopy, Cu K-edge X-ray absorption spectroscopy, and 1s2p resonant inelastic X-ray scattering in concert with density functional theory, multiplet theory, and multireference calculations, they were able to map the ground state electronic configuration. This showed that the lowest unoccupied orbital was of primarily trifluoromethyl character. This confirmed the presence of an inverted ligand field and started building experimental tools to probe this phenomenon. [8] Since the Snyder case, many other complexes of later transition metals have been shown to display inverted ligand field through both theoretical and experimental methods.

Probing inverted ligand fields

Computational and experimental techniques have been imperative for the study of inverted ligand fields, especially when used in cooperatively.

Computational

Computational methods have played a large role in understanding the nature of bonding in both molecular and solid-state systems displaying inverted ligand fields. The Hoffman group has completed many calculations to probe occurrence of inverted ligand fields in varying systems. [9] In a study of the absorption of CO on PtBi and PtBi2 surfaces, on an octahedral [Pt(BiH3)6]4+ model with a Pt thought of having a formal 4+ oxidation state, the team found that the t2g metal orbitals were higher energy that the eg orbitals. This inversion of the d orbital ordering was attributed to the bismuth based ligands being higher in energy than the metal d orbitals. [10] In another study involving calculations on Ag(III) salt KAgF4, other Ag(II), and Ag(III) compounds, the Ag d orbitals were found to be below those of the fluoride ligand orbitals, [11] and was confirmed by Grochala and cowrokers by core and valence spectroscopies. [12]

The Mealli group developed the program Computer Aided Composition of Atomic Orbitals (CACAO) to provide visualised molecular orbitals analyses based on perturbation theory principles. [13] This program successfully displayed orbital energy inversion with organometallic complexes containing electronegative metals such as Ni or Cu bound to electropositive ligand atoms such as B, Si, or Sn. [13] In these cases the bonding was described as a ligand to metal dative bond or sigma backdonation. [14]

Interaction of the filled p band of P4 ring sublattice with Co d block bands in CoP3. CoP3 ILF.png
Interaction of the filled p band of P4 ring sublattice with Co d block bands in CoP3.

Alvarez and coworkers used computational methods to illustrate ligand field inversion in the band structures of solid state materials. The group found that, contrary to the classical bonding scheme, in calculated MoNiP8 band structures the eg-type orbitals of the octahedral nickel atom were found to be the major component of an occupied band below the t2g set. [16] Additionally, the band around the fermi level which included the Ni+ antibonding orbitals were found to be mostly of phosphorus character, a clear example if an inverted ligand field. Similar observations were made in other solid state materials like the skutterudite CoP3 structure. [17] [15] A consequence of the inverted ligand field in this case is that the conductivity in skutterudites is associated with the phosphorus rings rather than the metal atoms.

Experimental

X-ray absorption spectroscopy (XAS) has been a powerful tool in deducing the oxidation states of transition metals. [18] Energy shifts in XAS are higher due to the higher effective nuclear charge of atoms in higher oxidations, presumably due to the higher binding energy for deeper, more core-like electrons. [2]

Despite this being a very powerful technique, competing effects on the rising edge positions can make assignment difficult. It was initially thought that the weak, quadrupole-allowed pre-edge peak assigned as the Cu 1s to 3d transition could be used to distinguish between Cu(II) and Cu(III) with the features appearing at 8979 +/- 0.3 eV and 8981 +/- 0.5 eV, respectively. [19] Ab initio calculations by Tomson, Wieghardt, and co-workers displayed that pre-peaks previously assigned as Cu(III) could be displayed by Cu(II) bearing complexes. [20] Many groups have displayed that metal K-edge XAS transitions involving ligand-localised acceptor orbitals, as well as spectral shifts from change in coordination environment, can make metal K-edge analysis less predictable. [21] [22] [23] [24]

The most sussessful use of K and L-edge XAS provide valuable information on the composition of molecular orbitals and display inverted ligand fields has been done in studies that made use of computational techniques in concert with experimental techniques. This was the case of the L2[Cu2(S2)n]2+ complexes of York, Brown, and Tolman, [25] and the Cu(CF3)4- by various groups including Hoffman, [2] Overgaard, [26] and Lancaster. [1] [8]

Another experimental tool used to probe ligand field inversion includes Electron paramagnetic resonance (ESR/EPR), which can provide information regarding the metal electronic configuration, the nature of the SOMO, and high resolution information on the ligands. [27]

Impact of charge and geometry

MO diagrams of frontier orbitals of [Cu(CF3)4) anions. MO (Cu(CF2)4)n-.png
MO diagrams of frontier orbitals of [Cu(CF3)4) anions.

Changes in both charge and geometry of organometallic complexes can greatly vary the energies of molecular orbitals and can therefore dictate the likelihood of observing an inverted ligand field. Hoffman and coworkers explored the impact of these variables by calculating the atomic composition of molecular orbitals for mono- di- and trianion copper complexes. [2] The square planar monoanion displayed the reported ligand field inversion. The "Cu(II)" which has an intermediate square planar to tetrahedral geometry also displayed this feature with the antibonding t2-derived orbital being mostly of ligand character and the x2-y2 orbital being the lowest molecular orbital of the d block. The tetrahedral trianion showed a return to the Werner-type ligand field. [2] By modulating the geometry of the "Cu(II)" species and displaying the change in energies of MO on walsh diagrams, the group was able to show how the complex could display both a classical and inverted ligand field when in Td and SP geometry respectively. [2] Additional calculations on the Cu(I) with non-tetrahedral geometry also displayed an inverted ligand field. This indicated the importance of not just oxidation state but geometry in determining the inversion of a ligand field.

Frontier orbitals of mono-, di-, and trianionic [Cu(CF3)4] calculated with the B3LYP functional using a D3BJ def2-TZVP(-f) basis and visualised by IboView. Cu CF3 4 n Frontier orbitals.png
Frontier orbitals of mono-, di-, and trianionic [Cu(CF3)4] calculated with the B3LYP functional using a D3BJ def2-TZVP(-f) basis and visualised by IboView.

Consequences on bonding

The inversion of ligand fields has interesting implications on the nature of reactivity of organometallic complexes. This sigma non-innocence of ligands arising from inverted ligand fields could therefore be used to tune reactivity of complexes and open space in understanding the mechanisms of existing reactions.

In an analysis of the [ZnF4]2- , it was found that due to ligand field inversion displayed in this species, core ionization removes an electron from the metal-rich bonding t2 orbital, lengthening the Zn-F bonds. This is contrary to the classical ligand field where ionization would remove an electron from the antibonding t2 orbital shortening the Zn-F bonds. [2]

The presence of electron-deficient ligands also result in an inverted ligand field. Calculations have shown that the large O 2p contribution into the LUMO/LUMO+1 in [(LTEEDCu)2(O2)]2+ should make the complex highly oxidizing as it contains electron deficient O2- ligands. [1] Studies have corroborated this property as this complex has shown to be able to undergo C-H and C-F activation and aromatic hydroxylation. [28] [29] [30]

There is evidence showing that reductive elimination on species displaying ligand field inversion do not undergo a redox event at the metal center. The C-CF3 bond formation by "Ni(IV)" complexes [31] was completed without redox participation of the Nickel. [32] The metal appears to remain Ni(II) throughout the reaction. The mechanism is thought to be through the attack of a masked electrophilic cation by anionic CF3. The electron deficiency here is due to the inverted ligand field. [32]

Related Research Articles

In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to other atoms were fully ionic. It describes the degree of oxidation of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. While fully ionic bonds are not found in nature, many bonds exhibit strong ionicity, making oxidation state a useful predictor of charge.

<span class="mw-page-title-main">Plastocyanin</span>

Plastocyanin is a copper-containing protein that mediates electron-transfer. It is found in a variety of plants, where it participates in photosynthesis. The protein is a prototype of the blue copper proteins, a family of intensely blue-colored metalloproteins. Specifically, it falls into the group of small type I blue copper proteins called "cupredoxins".

<span class="mw-page-title-main">Pi backbonding</span> Movement of electrons from one atoms orbital to a symmetric antibonding orbital on another

In chemistry, π backbonding, also called π backdonation, is when electrons move from an atomic orbital on one atom to an appropriate symmetry antibonding orbital on a π-acceptor ligand. It is especially common in the organometallic chemistry of transition metals with multi-atomic ligands such as carbon monoxide, ethylene or the nitrosonium cation. Electrons from the metal are used to bond to the ligand, in the process relieving the metal of excess negative charge. Compounds where π backbonding occurs include Ni(CO)4 and Zeise's salt. IUPAC offers the following definition for backbonding:

A description of the bonding of π-conjugated ligands to a transition metal which involves a synergic process with donation of electrons from the filled π-orbital or lone electron pair orbital of the ligand into an empty orbital of the metal (donor–acceptor bond), together with release (back donation) of electrons from an nd orbital of the metal (which is of π-symmetry with respect to the metal–ligand axis) into the empty π*-antibonding orbital of the ligand.

Reductive elimination is an elementary step in organometallic chemistry in which the oxidation state of the metal center decreases while forming a new covalent bond between two ligands. It is the microscopic reverse of oxidative addition, and is often the product-forming step in many catalytic processes. Since oxidative addition and reductive elimination are reverse reactions, the same mechanisms apply for both processes, and the product equilibrium depends on the thermodynamics of both directions.

<span class="mw-page-title-main">Metal carbonyl</span> Coordination complexes of transition metals with carbon monoxide ligands

Metal carbonyls are coordination complexes of transition metals with carbon monoxide ligands. Metal carbonyls are useful in organic synthesis and as catalysts or catalyst precursors in homogeneous catalysis, such as hydroformylation and Reppe chemistry. In the Mond process, nickel tetracarbonyl is used to produce pure nickel. In organometallic chemistry, metal carbonyls serve as precursors for the preparation of other organometallic complexes.

<span class="mw-page-title-main">Metal dithiolene complex</span>

Dithiolene metal complexes are complexes containing 1,2-dithiolene ligands. 1,2-Dithiolene ligands, a particular case of 1,2-dichalcogenolene species along with 1,2-diselenolene derivatives, are unsaturated bidentate ligand wherein the two donor atoms are sulfur. 1,2-Dithiolene metal complexes are often referred to as "metal dithiolenes", "metallodithiolenes" or "dithiolene complexes". Most molybdenum- and tungsten-containing proteins have dithiolene-like moieties at their active sites, which feature the so-called molybdopterin cofactor bound to the Mo or W.

Copper proteins are proteins that contain one or more copper ions as prosthetic groups. Copper proteins are found in all forms of air-breathing life. These proteins are usually associated with electron-transfer with or without the involvement of oxygen (O2). Some organisms even use copper proteins to carry oxygen instead of iron proteins. A prominent copper proteins in humans is in cytochrome c oxidase (cco). The enzyme cco mediates the controlled combustion that produces ATP.

In organic chemistry, carbon–hydrogen bond functionalization is a type of organic reaction in which a carbon–hydrogen bond is cleaved and replaced with a C−X bond. The term usually implies that a transition metal is involved in the C−H cleavage process. Reactions classified by the term typically involve the hydrocarbon first to react with a metal catalyst to create an organometallic complex in which the hydrocarbon is coordinated to the inner-sphere of a metal, either via an intermediate "alkane or arene complex" or as a transition state leading to a "M−C" intermediate. The intermediate of this first step can then undergo subsequent reactions to produce the functionalized product. Important to this definition is the requirement that during the C−H cleavage event, the hydrocarbyl species remains associated in the inner-sphere and under the influence of "M".

<span class="mw-page-title-main">Metal nitrosyl complex</span> Complex of a transition metal bonded to nitric oxide: Me–NO

Metal nitrosyl complexes are complexes that contain nitric oxide, NO, bonded to a transition metal. Many kinds of nitrosyl complexes are known, which vary both in structure and coligand.

In chemistry, a (redox) non-innocent ligand is a ligand in a metal complex where the oxidation state is not clear. Typically, complexes containing non-innocent ligands are redox active at mild potentials. The concept assumes that redox reactions in metal complexes are either metal or ligand localized, which is a simplification, albeit a useful one.

In X-ray absorption spectroscopy, the K-edge is a sudden increase in x-ray absorption occurring when the energy of the X-rays is just above the binding energy of the innermost electron shell of the atoms interacting with the photons. The term is based on X-ray notation, where the innermost electron shell is known as the K-shell. Physically, this sudden increase in attenuation is caused by the photoelectric absorption of the photons. For this interaction to occur, the photons must have more energy than the binding energy of the K-shell electrons (K-edge). A photon having an energy just above the binding energy of the electron is therefore more likely to be absorbed than a photon having an energy just below this binding energy or significantly above it.

<span class="mw-page-title-main">Metal L-edge</span>

Metal L-edge spectroscopy is a spectroscopic technique used to study the electronic structures of transition metal atoms and complexes. This method measures X-ray absorption caused by the excitation of a metal 2p electron to unfilled d orbitals, which creates a characteristic absorption peak called the L-edge. Similar features can also be studied by Electron Energy Loss Spectroscopy. According to the selection rules, the transition is formally electric-dipole allowed, which not only makes it more intense than an electric-dipole forbidden metal K pre-edge transition, but also makes it more feature-rich as the lower required energy results in a higher-resolution experiment.

Transition metal carbyne complexes are organometallic compounds with a triple bond between carbon and the transition metal. This triple bond consists of a σ-bond and two π-bonds. The HOMO of the carbyne ligand interacts with the LUMO of the metal to create the σ-bond. The two π-bonds are formed when the two HOMO orbitals of the metal back-donate to the LUMO of the carbyne. They are also called metal alkylidynes—the carbon is a carbyne ligand. Such compounds are useful in organic synthesis of alkynes and nitriles. They have been the focus on much fundamental research.

Metal carbon dioxide complexes are coordination complexes that contain carbon dioxide ligands. Aside from the fundamental interest in the coordination chemistry of simple molecules, studies in this field are motivated by the possibility that transition metals might catalyze useful transformations of CO2. This research is relevant both to organic synthesis and to the production of "solar fuels" that would avoid the use of petroleum-based fuels.

<span class="mw-page-title-main">Metal-phosphine complex</span>

A metal-phosphine complex is a coordination complex containing one or more phosphine ligands. Almost always, the phosphine is an organophosphine of the type R3P (R = alkyl, aryl). Metal phosphine complexes are useful in homogeneous catalysis. Prominent examples of metal phosphine complexes include Wilkinson's catalyst (Rh(PPh3)3Cl), Grubbs' catalyst, and tetrakis(triphenylphosphine)palladium(0).

<span class="mw-page-title-main">Transition metal thiolate complex</span>

Transition metal thiolate complexes are metal complexes containing thiolate ligands. Thiolates are ligands that can be classified as soft Lewis bases. Therefore, thiolate ligands coordinate most strongly to metals that behave as soft Lewis acids as opposed to those that behave as hard Lewis acids. Most complexes contain other ligands in addition to thiolate, but many homoleptic complexes are known with only thiolate ligands. The amino acid cysteine has a thiol functional group, consequently many cofactors in proteins and enzymes feature cysteinate-metal cofactors.

<span class="mw-page-title-main">Transition metal nitrile complexes</span> Class of coordination compounds containing nitrile ligands (coordinating via N)

Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.

Heterobimetallic catalysis is an approach to catalysis that employs two different metals to promote a chemical reaction. Included in this definition are cases where: 1) each metal activates a different substrate, 2) both metals interact with the same substrate, and 3) only one metal directly interacts with the substrate(s), while the second metal interacts with the first.

<span class="mw-page-title-main">Nontrigonal pnictogen compounds</span>

Nontrigonal pnictogen compounds refer to tricoordinate trivalent pnictogen compounds that are not of typical trigonal pyramidal molecular geometry. By virtue of their geometric constraint, these compounds exhibit distinct electronic structures and reactivities, which bestow on them potential to provide unique nonmetal platforms for bond cleavage reactions.

Sigma non-innocence is a special form of non-innocence, an oxidation characteristic in metal complexes. It is mainly discussed in coordination complexes of late transition metals in their high formal oxidation states. Complexes exhibiting sigma non-innocence differ from classical Werner coordination complexes in that their bonding and antibonding orbitals have an inverted distribution of metal and ligand character. The oxidation of the ligand and a lowered charge at the metal center renders the assignment of the oxidation state non-trivial.

References

  1. 1 2 3 4 DiMucci, Ida M.; Lukens, James T.; Chatterjee, Sudipta; Carsch, Kurtis M.; Titus, Charles J.; Lee, Sang Jun; Nordlund, Dennis; Betley, Theodore A.; MacMillan, Samantha N.; Lancaster, Kyle M. (2019-11-20). "The Myth of d 8 Copper(III)". Journal of the American Chemical Society. 141 (46): 18508–18520. doi:10.1021/jacs.9b09016. ISSN   0002-7863. PMC   7256958 . PMID   31710466.
  2. 1 2 3 4 5 6 7 8 9 10 11 Hoffmann, Roald; Alvarez, Santiago; Mealli, Carlo; Falceto, Andrés; Cahill, Thomas J.; Zeng, Tao; Manca, Gabriele (2016-07-27). "From Widely Accepted Concepts in Coordination Chemistry to Inverted Ligand Fields". Chemical Reviews. 116 (14): 8173–8192. doi:10.1021/acs.chemrev.6b00251. ISSN   0009-2665. PMID   27398715.
  3. ↑ Albright, Thomas A. (2013). Orbital interactions in chemistry. Jeremy K. Burdett, Myung-Hwan Whangbo (2nd ed.). Hoboken, New Jersey. ISBN   978-0-471-08039-8. OCLC   823294395.{{cite book}}: CS1 maint: location missing publisher (link)
  4. ↑ Griffith, J. S.; Orgel, L. E. (1957-01-01). "Ligand-field theory". Quarterly Reviews, Chemical Society. 11 (4): 381–393. doi:10.1039/QR9571100381. ISSN   0009-2681.
  5. 1 2 Snyder, James (1995). "Distinguishing Copper d8 and d10 Configurations in a Highly Ionic Complex; A Nonformal Metal Oxidation State". Angewandte Chemie International Edition in English. 35 (9): 986–987. doi:10.1002/anie.199509862 – via Wiley.
  6. ↑ Naumann, Dieter; Roy, Thomas; Tebbe, Karl-Friedrich; Crump, Wolfgang (1993-10-10). "Synthesis and Structure of Surprisingly Stable Tetrakis(trifluoromethyl)cuprate(III) Salts". Angewandte Chemie International Edition in English. 32 (10): 1482–1483. doi:10.1002/anie.199314821. ISSN   0570-0833.
  7. ↑ Aullón, Gabriel; Alvarez, Santiago (2009-05-01). "Oxidation states, atomic charges and orbital populations in transition metal complexes". Theoretical Chemistry Accounts. 123 (1): 67–73. doi:10.1007/s00214-009-0537-9. ISSN   1432-2234. S2CID   97419872.
  8. 1 2 Walroth, Richard C.; Lukens, James T.; MacMillan, Samantha N.; Finkelstein, Kenneth D.; Lancaster, Kyle M. (2016-02-17). "Spectroscopic Evidence for a 3d 10 Ground State Electronic Configuration and Ligand Field Inversion in [Cu(CF 3 ) 4 ] 1–". Journal of the American Chemical Society. 138 (6): 1922–1931. doi:10.1021/jacs.5b10819. ISSN   0002-7863. PMID   26844693.
  9. ↑ Zheng, Chong; Hoffmann, Roald (1989-03-01). "Conjugation in the 3-connected net: the aluminum diboride and thorium disilicide structures and their transition-metal derivatives". Inorganic Chemistry. 28 (6): 1074–1080. doi:10.1021/ic00305a015. ISSN   0020-1669.
  10. ↑ Oana, Melania; Hoffmann, Roald; Abruña, Héctor D.; DiSalvo, Francis J. (2005-01-01). "Adsorption of CO on PtBi2 and PtBi surfaces". Surface Science. 574 (1): 1–16. Bibcode:2005SurSc.574....1O. doi:10.1016/j.susc.2004.09.045. ISSN   0039-6028.
  11. ↑ Grochala, Wojciech; Hoffmann, Roald (2010-05-24). "ChemInform Abstract: Real and Hypothetical Intermediate-Valence AgII/AgIII and AgII/AgI Fluoride Systems as Potential Superconductors". ChemInform. 32 (43): no. doi:10.1002/chin.200143247. ISSN   0931-7597.
  12. ↑ Grochala, Wojciech; Egdell, Russ G.; Edwards, Peter P.; Mazej, Zoran; Žemva, Boris (2003-09-10). "On the Covalency of Silver-Fluorine Bonds in Compounds of Silver(I), Silver(II) and Silver(III)". ChemPhysChem. 4 (9): 997–1001. doi:10.1002/cphc.200300777. ISSN   1439-4235. PMID   14562447.
  13. 1 2 Mealli, Carlo; Proserpio, Davide M. (1990-05-01). "MO theory made visible". Journal of Chemical Education. 67 (5): 399. Bibcode:1990JChEd..67..399M. doi:10.1021/ed067p399. ISSN   0021-9584.
  14. ↑ Mealli, Carlo; Ghilardi, Carlo A.; Orlandini, Annabella (1992-11-01). "Structural flexibility and bonding capabilities of the ligand np3 toward the transition metals". Coordination Chemistry Reviews. 120: 361–387. doi:10.1016/0010-8545(92)80059-z. ISSN   0010-8545.
  15. 1 2 Llunell, Miquel; Alvarez, Santiago; Alemany, Pere (1998). "Skutterudite vs. ReO3 structures for MX3 solids: electronic requirements". Journal of the Chemical Society, Dalton Transactions (7): 1195–1200. doi:10.1039/a708200b. ISSN   0300-9246.
  16. ↑ LLUNELL, M.; ALVAREZ, S.; ALEMANY, P.; HOFFMANN, R. (2010-08-04). "ChemInform Abstract: Electronic Structure, Bonding, and Electrical Properties of MoNiP8". ChemInform. 27 (46): no. doi:10.1002/chin.199646001. ISSN   0931-7597.
  17. ↑ Llunell, Miquel; Alemany, Pere; Alvarez, Santiago; Zhukov, Vladlen P.; Vernes, Andreas (1996-04-15). "Electronic structure and bonding in skutterudite-type phosphides". Physical Review B. 53 (16): 10605–10609. Bibcode:1996PhRvB..5310605L. doi:10.1103/physrevb.53.10605. hdl:2445/10836. ISSN   0163-1829. PMID   9982624.
  18. ↑ Glaser, Thorsten; Hedman, Britt; Hodgson, Keith O.; Solomon, Edward I. (2001-03-06). "ChemInform Abstract: Ligand K-Edge X-Ray Absorption Spectroscopy: A Direct Probe of Ligand-Metal Covalency". ChemInform. 32 (10): no. doi:10.1002/chin.200110300. ISSN   0931-7597.
  19. ↑ DuBois, Jennifer L.; Mukherjee, Pulakesh; Stack, T. D. P.; Hedman, Britt; Solomon, Edward I.; Hodgson, Keith O. (2000-06-01). "A Systematic K-edge X-ray Absorption Spectroscopic Study of Cu(III) Sites". Journal of the American Chemical Society. 122 (24): 5775–5787. doi:10.1021/ja993134p. ISSN   0002-7863.
  20. ↑ Tomson, Neil C.; Williams, Kamille D.; Dai, Xuliang; Sproules, Stephen; DeBeer, Serena; Warren, Timothy H.; Wieghardt, Karl (2015). "Re-evaluating the Cu K pre-edge XAS transition in complexes with covalent metal–ligand interactions". Chemical Science. 6 (4): 2474–2487. doi:10.1039/c4sc03294b. ISSN   2041-6520. PMC   5647745 . PMID   29308158. S2CID   246748080.
  21. ↑ "Xray Absorption Spectroscopy as a Probe of Ligand Noninnocence in Metallocorroles: The Case of Copper Corroles". doi:10.1021/acs.inorgchem.9b00128.s001. hdl:10037/18125 . Retrieved 2023-03-12.{{cite journal}}: Cite journal requires |journal= (help)
  22. ↑ Walroth, Richard C.; Uebler, Jacob W. H.; Lancaster, Kyle M. (2015). "Probing CuI in homogeneous catalysis using high-energy-resolution fluorescence-detected X-ray absorption spectroscopy". Chemical Communications. 51 (48): 9864–9867. doi:10.1039/c5cc01827g. ISSN   1359-7345. PMC   4540364 . PMID   25994112.
  23. ↑ Carsch, Kurtis M.; DiMucci, Ida M.; Iovan, Diana A.; Li, Alex; Zheng, Shao-Liang; Titus, Charles J.; Lee, Sang Jun; Irwin, Kent D.; Nordlund, Dennis; Lancaster, Kyle M.; Betley, Theodore A. (2019-09-13). "Synthesis of a copper-supported triplet nitrene complex pertinent to copper-catalyzed amination". Science. 365 (6458): 1138–1143. Bibcode:2019Sci...365.1138C. doi:10.1126/science.aax4423. ISSN   0036-8075. PMC   7256962 . PMID   31515388.
  24. ↑ KAU, L.-S.; SPIRA-SOLOMON, D. J.; PENNER-HAHN, J. E.; HODGSON, K. O.; SOLOMON, E. I. (1988-02-09). "ChemInform Abstract: X-Ray Absorption Edge Determination of the Oxidation State and Coordination Number of Copper: Application to the Type 3 Site in Rhus vernicifera Laccase and Its Reaction with Oxygen". ChemInform. 19 (6). doi:10.1002/chin.198806038. ISSN   0931-7597.
  25. ↑ Sarangi, Ritimukta; York, John T.; Helton, Matthew E.; Fujisawa, Kiyoshi; Karlin, Kenneth D.; Tolman, William B.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I. (2008-01-01). "X-Ray Absorption Spectroscopic and Theoretical Studies on (L) 2 [Cu 2 (S 2 ) n ] 2+ Complexes: Disulfide versus Disulfide(•1−) Bonding". Journal of the American Chemical Society. 130 (2): 676–686. doi:10.1021/ja0762745. ISSN   0002-7863. PMC   2570853 . PMID   18076173.
  26. ↑ Overgaard, Jacob (2019-01-15). "Experimental X-ray Electron Density Study of Atomic Charges, Oxidation States, and Inverted Ligand Field in Cu(CF3)4–". Inorganic Chemistry. 58 (3): 2133–2139. doi:10.1021/acs.inorgchem.8b03226. hdl:2434/971202. PMID   30645110. S2CID   58640050.
  27. ↑ Kisgeropoulos, Effie C.; Manesis, Anastasia C.; Shafaat, Hannah S. (2021-01-20). "Ligand Field Inversion as a Mechanism to Gate Bioorganometallic Reactivity: Investigating a Biochemical Model of Acetyl CoA Synthase Using Spectroscopy and Computation". Journal of the American Chemical Society. 143 (2): 849–867. doi:10.1021/jacs.0c10135. ISSN   0002-7863. PMID   33415980. S2CID   231195483.
  28. ↑ Mirica, Liviu M.; Ottenwaelder, Xavier; Stack, T. Daniel P. (2004-05-11). "Structure and Spectroscopy of Copper—Dioxygen Complexes". ChemInform. 35 (19). doi:10.1002/chin.200419297. ISSN   0931-7597.
  29. ↑ Company, Anna; Palavicini, Sara; Garcia-Bosch, Isaac; Mas-Ballesté, Ruben; Que, Lawrence; Rybak-Akimova, Elena V.; Casella, Luigi; Ribas, Xavi; Costas, Miquel (2008-04-18). "Tyrosinase-Like Reactivity in a CuIII2(μ-O)2 Species". Chemistry - A European Journal. 14 (12): 3535–3538. doi:10.1002/chem.200800229. ISSN   0947-6539. PMID   18348133.
  30. ↑ Serrano-Plana, Joan; Garcia-Bosch, Isaac; Miyake, Ryosuke; Costas, Miquel; Company, Anna (2014-09-01). "Selective Ortho -Hydroxylation-Defluorination of 2-Fluorophenolates with a Bis(μ-oxo)dicopper(III) Species". Angewandte Chemie International Edition. 53 (36): 9608–9612. doi:10.1002/anie.201405060. PMID   25044926.
  31. ↑ Bour, James R.; Camasso, Nicole M.; Sanford, Melanie S. (2015-06-16). "Oxidation of Ni(II) to Ni(IV) with Aryl Electrophiles Enables Ni-Mediated Aryl–CF3 Coupling". Journal of the American Chemical Society. 137 (25): 8034–8037. doi:10.1021/jacs.5b04892. ISSN   0002-7863. PMID   26079544.
  32. 1 2 Steen, Jelte S.; Knizia, Gerald; Klein, Johannes E. M. N. (2019-07-15). "σ‐Noninnocence: Masked Phenyl‐Cation Transfer at Formal Ni(IV)". Angewandte Chemie. 131 (37): 13267–13273. doi:10.1002/ange.201906658. ISSN   0044-8249. S2CID   241689909.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.