Orbital interactions metal, description

The Fenske-Hall method is a modification of crystal held theory. This is done by using a population analysis scheme, then replacing orbital interactions with point charge interactions. This has been designed for the description of inorganic metal-ligand systems. There are both parameterized and unparameterized forms of this method. 

The primary objective of this paper is to illustrate by specific examples from our past and current research how electrical property measurements can be of value in deducing information regarding the solid-state electronic structure and in studying intermolecular orbital interactions in such transition metal complex systems. To facilitate this discussion, a brief description of electrical conductivity and some other electrical properties is included. For a more detailed account as well as for a description of the various experimental techniques which are used to determine these properties, the reader is referred to any of several excellent books on the subject (12,13). 

Suggest an orbital interaction diagram that is suitable for the description of the bond between the metallic centre and the methyl group in this mixed complex. 

This is a description of bonding in terms of the interactions between metal and ligand frontier orbitals to form molecular orbitals. It uses some crystal field theory terminology but focuses on orbital interactions rather than attractions between ions. 

In a weak field, atomic considerations dictate which orbitals are filled, as was the case in the rare earths. Atomic states described by term symbols of total L and S describe the states for d orbital occupation these are spht by the d—d electrostatic repulsions. Spin orbital interaction is small in the transition metals and usually neglected in the first-order description of the levels. A weak crystal field shifts the levels and effects a spfitting which occurs because the crystal field removes the degeneracy of an L level the L level splits into its components. Atomic free ion wave functions having the S5unmetry of the crystal field are used to calculate the splittings. 

The simple perturbative treatment of spin-free terms from the Pauh Hamiltonian does reasonably well for the two light members of the series, but less so for AuH. As this approximation is extremely easy to program for SCF calculations and requires almost no extra computational effort, it appears as an attractive qualitative approach to relativity in medium heavy species. Only the Dirac-Coulomb (DC) results in table 22.3 account for spin-orbit interaction. The closeness of DKH and RECP results to the DC values indicate that spin-orbit effects are of minor importance, something we would expect in closed-shell molecules, where the bonding is dominated by s orbitals. Under these conditions, the two approximate spin-free methods can compete with the full DC operator. The agreement between the results from these three schemes also indicate that the discrepancy between the calculated and experimental values is due to insufficient description of the correlation. This observation is in line with the common experience that MP2 calculations on transition-metal compounds frequently yield somewhat short bond lengths. 

Molecular orbital calculations give a detailed description of the ligand-metal orbital interactions and resulting energy diagram of the complex. 

In many of their complexes PF3 and PPI13 (for example) resemble CO (p. 926) and this at one time encouraged the belief that their bonding capabilities were influenced not only by the factors (p. 198) which affect the stability of the a P M interaction which uses the lone-pair of elecU"ons on p and a vacant orbital on M, but also by the possibility of synergic n back-donation from a nonbonding d , pair of electrons on the metal into a vacant 3d , orbital on P. It is, however, not clear to what extent, if any, the a and n bonds reinforce each other, and more recent descriptions are based on an MO approach which uses all (cr and n) orbitals of appropriate symmeU"y on both the phosphine and the metal-containing moiety. To the extent that a and n bonding effects on the stability of metal-phosphorus bonds can be isolated from each otlier and from steric factors (see below) the accepted sequence of effects is as follows ... 

For a theoretical consideration of the metal-silicon interaction in silylene complexes, the fragment orbital description proves to be very useful [148], This approach has been extensively used in the organometallic chemistry of carbon and allows a basic understanding of the interrelations also by means of a qualitative description. 

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