Bonding block metal complexes

A representative molecular orbital diagram for an octahedral d-block metal complex ML6 is shown in Figure 1.8. The MOs are classified as bonding (oL and ttL), nonbonding (jtM) and antibonding (o, nl and ). The ground-state electronic configuration of an octahedral complex... 

Rare earth coordination chemistry has many characteristic properties compared with d-block metal complexes. Four main issues will be discussed in this section the valence state, chemical bonding, the coordination number, and the tetra effect - the changing gradation rules in rare earth coordination chemistry. 

A large number of J-block metal complexes containing coordinated N2 are known (see Figure 14.9 and equations 22.95 and 22.96 and discussion) N2 is isoelectronic with CO and the bonding in complexes containing the N2 ligand can be described in a similar manner to that in metal carbonyl complexes (see Chapter 23). 

Bonding in d-block metal complexes valence Bonding in d-block metal complexes molecular... 

Ligand field, like crystal field, theory is confined to the role of d orbitals, but unlike the crystal field model, the ligand field approach is not a purely electrostatic model. It is a freely parameterized model, and uses and Racah parameters (to which we return later) which are obtained from electronic spectroscopic (i.e. experimental) data. Most importantly, although (as we showed in the last section) it is possible to approach the bonding in d-block metal complexes by using molecular orbital theory, it is incorrect to state that ligand field theory is simply the application of MO theory. ... 

A characteristic feature of many d-block metal complexes is their colours, which arise because they absorb light in the visible region (see Figure 20.4). Studies of electronic spectra of metal complexes provide information about structure and bonding, although interpretation of the spectra is not always straightforward. Absorptions arise from transitions between electronic energy levels ... 

G. Frenking (2001) Journal of Organometallic Chemistry, vol. 635, p. 9 - An assessment of the bonding in d-block metal complexes including carbonyls which considers the relative importance of a and tt, as well as electrostatic, contributions to the metal-ligand bonds. 

Bonding in c/-block metal complexes valence bond theory... 

Bonding in of-block metal complexes crystal field theory... 

In this chapter, we discuss complexes of the -block metals and we consider bonding theories that rationalize experimental facts such as electronic spectra and magnetic properties. Most of our discussion centres on first row J-block metals, for which theories of bonding are most successful. The bonding in fif-block metal complexes is not fundamentally different from that in other compounds, and we shall show applications of valence bond theory, the electrostatic model and molecular orbital theory. 

Early -block metal complexes containing one or two Qt-hydrogen atoms (see 24.47) may undergo a-hydrogen abstraction to yield carbene (alkylidene, 24.49) or carbyne alkylidyne, 24.50) complexes. The solid state structure of the product of reaction 24.45 confirms differences in the Ta—C bond lengths 225 pm for Ta—Caikyi and 205 pm for Ta Ccarbene-... 

---