Molecular orbital energy level schemes

Figure 8-5 Molecular-orbital energy-level scheme for an octahedral complex.

The general molecular orbital energy level schemes arrived at for square planar complexes are given in Fig. 2 (case 1) and Fig. 3 (case 2). Group molecular orbital overlap integrals (for Ni(CN)42-) and ligand exchange interactions are summarized in Table II. 

Fig. 2.—Molecular orbital energy level scheme for square planar utetal complexes in which there is no intra-ligand ir-orbital system (case 1).

Fig. 3.—Molecular orbital energy level scheme for square planar metal complexes in which the ligands themselves have a r-orbltal system (case 2).

It is important to establish the main similarities and differences in the electronic spectra of isoelectronic metal carbonyls and cyanides and to relate these spectral comparisons to the nature of the M-CN and M—CO bonds. In this paper the electronic spectra of d6 metal carbonyls and cyanides are assigned on the basis of a derived molecular orbital energy level scheme. The differences in the energies erf the single electron molecular orbitals for representative metal hexa-carbonyls and hexacyanides are obtained and a general discussion erf electronic structure is presented. 

Finally, there are tig and tau rb and tt ligand orbital combinations which do not interact with metal orbitals. The molecular orbital energy level scheme expected for the bonding situation described above is shown in Fig. 2. 

Approximate molecular orbital energy level scheme for the M—M interactions in tetragonal-prismatic two-metai dusters,... 

The bonding in metal hexacarbonyls and hexacyanides is described in terms of molecular orbitals. Vapor phase electronic spectra for the metal hexacarbonyls are reported in the range 35(X)-1700 k. A molecular orbital energy level scheme is presented which is able to account for the observed d-d and charge-transfer absorption bands in the d met complexes. The charge-transfer transitions all are assigned as metal (d) to ligand (v ). 

ENERGY LEVELS POR BcH2 The molecular-orbital energy-level scheme for BeH2, shown in Fig. 3-5, is constructed as follows The valence orbitals of the central atom are indicated on the left-hand side of the diagram, with... 

The molecular-orbital energy-level scheme for BF3 is shown in Fig, 4-7. The fluorine valence orbitals are more stable than the boron valence orbitals, and so electrons in bonding molecular orbitals spend more time in the domain of the fluorine nuclei. The a- and (Tj molecular orbitals are degenerate in trigonal-planar molecules such as BF. Since this is by no means obvious from Eqs. (4-3), (4-4), (4-5), and (4-6), we shall devote a short section to an explanation. 

The molecular-orbital energy-level scheme for CH4 is shown in Fig. 5-5. The 0, and tetrahedral molecule and are degenerate in energy. This is clear from the overlaps shown in Figs. 5-3 and 5-4. 

The molecular-orbital energy-level scheme for NH3 is shown in Fig. 6-10. The Ox and ay orbitals are degenerate. The eight valence electrons give a ground-state configuration of... 

The molecular-orbital energy-level scheme is shown in Fig. 7-4, with the hydrogen Ij- orbital placed above the oxygen Is and Ip valence orbitals. The molecular orbital is seen to be more stable than the owing to the interaction of [Pg.142]

Fig. 6. 11 A schematic molecular orbital energy level scheme for an octahedral complex of a first row transition metal ion (only c interactions are included). The ligand orbitals are shown occupied the metal d orbitals are partially filled. The example shown is appropriate to a d ion in a strong-field (low-spin) complex. The full meaning of these latter terms will only become evident in Chapter 7. The numbers in parenthesis follow the established convention of counting from the bottom up. So, the bottom is a d), the next aj (2).

Figure 23. Schematic presentation of the molecular orbital energy-level scheme for the TiO " cluster in BaTiO -type crystals. The highest occupied MO are formed by the atomic 2p orbitals of the six oxygen ions, while the lowest unoccupied ones belong to empty 3d orbitals of the Ti" ion their pseudo Jahn-Teller mixing under the off-center displacements of the titanium atom results in a specific APES with eight minima and two types of saddle points which explain the origin of the ferroelectric phases and their partial disorder (Reprinted with permission from Ref. 74. Copyright 2014, Elsevier Publishing Company).

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