Ethylene and Related Ligands

TABLE 18.4 Tolman cone angles 0) for selected phosphine ligands. 

Metal-ligand bonding in organometallic compounds containing a phosphine ligand. 

Definition of Tolman s cone angle for phosphine ligands. 

Simplified one-electron MO diagram for a metal-olefin bond. 

Example 18-6. Use MOT to predict whether the bound ethylene ligand in [Fe(CO)5(C2H4)] will lie completely in the equatorial plane, as shown at left, or parallel to the two axial positions, as shown at right. Define the vertical axis of the molecule as the z-axis, so that the equatorial plane is the xy-plane, and let the x-axis bisect the C=C bond in the coordinated ethylene. 

---