Bonding and Electronic Properties

Mixing of (r -orbitals in P(lll) ligands with the phosphorus d-orbital and the symmetry of orbital interactions in metal-phosphine backbonding. 

Experimental data on the ir-accepting ability of alkylphosphines are ambiguous. Photoelectron spectroscopy indicates that aliphatic phosphines are poor Tr-acceptors, ° but one study on a complex with an electron-rich (P metal center suggested that the relative energies of electronic states could be influenced by rr-back-donation into the cr-bonding orbitals of an aliphatic phosphine. The NBO analysis concluded that alkylphosphines are effective ir-acids. Tlius, further debate is likely to ensue about the ir-accepting ability of alkylphosphines, but other phosphorus ligands are clearly ir-acceptors. 

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Intramolecular Bonding and Electronic Properties of Liquid Crystal Molecules... 

Fig. 16 Early examples of MIM cartoons, (a) Sauvage s cartoon of a [3]catenand [101]. (b) Synthetic scheme of a donor-acceptor [2]catenane that uses illustration to emphasize topology, noncovalent bonding, and electronic properties [102]. Reproduced with permission from [101] (copyright 1985 American Chemical Society), [102] (copyright 1991 Wiley-VCH)...

J. Sun et al.. Chemical Bonding and Electronic Properties of SeS2-Treated GaAs(lOO), J. Appl. Phys. 1999, 85, 969-977. 

Table 2.8 Bond dissociation energies (BDE) of PdCeo-Pd bonds and electronic properties of PdiCeo...

The method of superposition of configurations as well as the method of different orbitals for different spins belong within the framework of the one-electron scheme, but, as soon as one introduces the interelectronic distance rijt a two-electron element has been accepted in the theory. In treating the covalent chemical bond and other properties related to electron pairs, it may actually seem more natural to consider two-electron functions as the fundamental building stones of the total wave function, and such a two-electron scheme has also been successfully developed (Hurley, Lennard-Jones, and Pople 1953, Schmid 1953). 

After a discussion of the properties of substances containing ionic bonds and electron-pair bonds, it is shown that the transition from one extreme bond type to another could take place continuously in some cases (when... 

In this contribution it is shown that local density functional (LDF) theory accurately predicts structural and electronic properties of metallic systems (such as W and its (001) surface) and covalently bonded systems (such as graphite and the ethylene and fluorine molecules). Furthermore, electron density related quantities such as the spin density compare excellently with experiment as illustrated for the di-phenyl-picryl-hydrazyl (DPPH) radical. Finally, the capabilities of this approach are demonstrated for the bonding of Cu and Ag on a Si(lll) surface as related to their catalytic activities. Thus, LDF theory provides a unified approach to the electronic structures of metals, covalendy bonded molecules, as well as semiconductor surfaces. 

Copper, iron, and aluminum are three common metals in modem society. Copper wires carry the electricity that powers most appliances, including the lamp by which you may be reading. The chair in which you are sitting may have an iron frame, and you may be sipping a soft drink from an aluminum can. The properties that allow metals to be used for such a wide range of products can be traced to the principles of bonding and electronic structure. 

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