Orbitals of ligands

If the unpaired electron is in a MO which includes atomic orbitals of ligand atoms, there is the possibility of a hyperfine interaction between the electron and the nuclear moment of the ligand atom. To see how these hyperfine terms can be calculated from the molecular orbitals we shall consider the dl case of Sec. V.C in which B is the ground state. 

Complexes of 1,2-dithiolate dianions (225) are of interest, although because they undergo successive one-electron transfer processes which involve orbitals of ligand character so unlike those of the dithiocarbamate type of ligand, it is unprofitable to attempt to assign oxidation states.995,1005 The chromium complexes are shown in Table 89. 

Donation of electrons from filled d orbitals of metal to empty t antibonding orbitals of ligand CO, RNC, pyridine. CN N2, NOJ, ethylene... 

Transition metal complexes comprise a typical example. The lone pair orbitals of ligands like CO, H20, Cl-, and O2- experience significant repulsion from the upper core shells 3s and 3p (first transition series). The Pauli repulsion with these shells determines the repulsive wall in the metal-ligand -versus-R curve. Of course, there is also overlap with deeper core orbitals, and so their effect is less important. An illustration is provided elsewhere (Figures 2 and 3 of Ref. 35), where the behavior of the Pauli repulsion is demonstrated along the Mn—O bond distance in MnO. The fragments are Mn2+, which has 5 electrons with spin up in the 3d orbitals, and the 02 cage, which has 5 electrons... 

Donation of electrons from fliled d orbitals of metal to empty [Pg.755]

In contrast to C2H4 and CO where the acceptor orbital is not degenerate with the donor orbital, the acceptor orbitals of ligands such as NO and (if-CyHy) are degenerate with a donor orbital. For these ligands, it is, therefore appropriate to include fully the Z component in the [ML/X Z ] classification. 

Table 10.1. Orbitals of Ligands, the Metal, and Molecular Orbitals for M(arene)2 Complexes...

Characteristic of d-block transition elements. Covalent interaction between 2p orbitals of ligand and valence orbitals, (n-l)d, ns and np of metal (Chapter 6). Involvement of metal d-orbitals important. 18-Electron configuration of metal commonly associated with kinetic stability. ... 

Arenes are usefril 7c-ligands of transition metals. The metal-arene bonding comprises both rr-donation from ligand to empty d-orbital of metal and rr-back-donation from filled metal d-orbital to 7i -orbital of ligand, and... 

Figure 7.22 (a) Unlike s and p orbitals, d orbitals are not all symmetric. The d t-axis, for example, has lobes that project out into the x-z plane there is no electron density along the axes, only between them, (b) Where overlap occurs with the orbitals of ligands, bonding interactions occur nonbonding interactions occur where there is no electron density and no overlap. 

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