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Inverted Ligand Field Theory
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. 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 chemistry, organometallic complexes, ligands are more electronegative and have frontier orbitals below those of the d orbitals of electropositive metals. Towards the right of the d-block, when approaching the transition-metalmain 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. 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 complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MO Diagrams Ligand Field
Mo or MO may refer to: Arts and entertainment Fictional characters * Mo, a girl in the ''Horrible Histories (2001 TV series), Horrible Histories'' TV series * Mo, also known as Mortimer, in the novel ''Inkheart'' by Cornelia Funke * Mo, in the webcomic ''Jesus and Mo'' * Mo, the main character in the ''Mo's Mischief'' children's book series * Mo, an ophthalmosaurus from ''The Land Before Time (franchise), The Land Before Time'' franchise * MO (Maintenance Operator), a robot in the Filmation series ''Young Sentinels'' * Mo, a main character in ''Zoey's Extraordinary Playlist'' * M-O (Microbe Obliterator), a robot in the film ''WALL-E'' * Mo the clown, a character played by Roy Rene, 20th-century Australian stage comedian * Mo Effanga, in the BBC medical drama series ''Holby City'' * Mo Harris, in the BBC soap opera ''EastEnders'' * Little Mo Mitchell, in the BBC soap opera ''EastEnders'' Films * "Mo" (魔 demon), original title of ''The Boxer's Omen'', a 1983 Hong Kong film * Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Absorption Spectroscopy
X-ray absorption spectroscopy (XAS) is a set of advanced techniques used for probing the local environment of matter at atomic level and its electronic structure. The experiments require access to synchrotron radiation facilities for their intense and tunable X-ray beams. Samples can be in the gas phase, solutions, or solids. Background XAS data are obtained by tuning the photon energy, using a crystalline monochromator, to a range where core electrons can be excited (0.1-100 keV). The edges are, in part, named by which core electron is excited: the principal quantum numbers n = 1, 2, and 3, correspond to the K-, L-, and M-edges, respectively. For instance, excitation of a 1s electron occurs at the metal K-edge, K-edge, while excitation of a 2s or 2p electron occurs at an metal L-edge, L-edge (Figure 1). There are three main regions found on a spectrum generated by XAS data, which are then thought of as separate spectroscopic techniques (Figure 2): # The ''absorption thresho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Bonding
A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects. Chemical bonds are described as having different strengths: there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force, and hydrogen bonding. Since opposite electric charges attract, the negatively charged electrons surrounding the nucleus and the positively charged protons within a nucleus attract each other. Electrons shared between two nuclei will be attracted to both of them. "Constructive quantum mechanical wavefunction interference" stabilizes the paired nuclei (see Theories of chemical bonding). Bonded nuclei maintain an optimal distance (t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma Non-innocence
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 (cf. inverted ligand field). The oxidation of the ligand and a lowered charge at the metal center renders the assignment of the oxidation state non-trivial. Sigma non-innocence in copper complexes Sigma non-innocence has been extensively discussed for the prototypical example of a copper complex u(CF3)4sup>− in conjunction with the concept of an inverted ligand field. In 1995, Snyder suggested, based on his quantum chemical calculations, that this formal Cu(III) (d8) complex would be more appropriately represented as a Cu(I) (d10) complex. Snyder pointed out that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walsh Diagram
Walsh diagrams, often called angular coordinate diagrams or correlation diagrams, are representations of calculated orbital binding energies of a molecule versus a distortion coordinate (bond angles), used for making quick predictions about the geometries of small molecules. By plotting the change in molecular orbital levels of a molecule as a function of geometrical change, Walsh diagrams explain why molecules are more stable in certain spatial configurations (e.g. why water adopts a bent conformation). A major application of Walsh diagrams is to explain the regularity in structure observed for related molecules having identical numbers of valence electrons (e.g. why H2O and H2S look similar), and to account for how molecules alter their geometries as their number of electrons or spin quantum number, spin state changes. Additionally, Walsh diagrams can be used to predict distortions of molecular geometry from knowledge of how the LUMO (Lowest Unoccupied Molecular Orbital) affects ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
