Question

What would a six coordinate metal-ligand complex structure look like?

Answer 1

The bonds are in an octahedral shape.

Explanation:

Let's take Sulphur hexaflouride (SF`""_6`) for example. Electron repulsion theory would say that for 6 bonds and 0 lone pairs of electrons, the four floruine atoms would be spread out evenly into a octahedron shape.

Since a complex is just molecules forming dative covalent bonds with a metal, the idea works the same way. Molecules will spread out evenly, for example in hexaaquairon(II) there are 6 water molecules dative covalently bonded to the Fe`""^(2+)` ion. The water molecules will evenly spread out.

Another example is EDTA, its a polydentate ligand that forms 6 dative covalent bonds. When it bonds to a metal ion, all 6 bonds are created, and are also spread out too.

Answer 2

Most likely, octahedral.

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There are exceptions, but for the most part, a simple metal-ligand complex is usually octahedral.

This just forms the most symmetric geometry, with equal bond angles for all adjacent ligands. It therefore minimizes bond-pair-bond-pair electron repulsions in most cases.

The main exception is trigonal prismatic:

This particular compound is air-sensitive, subliming at `-30^@ "C"`.

It is thermodynamically stabilized due to tungsten's `d^0` configuration, which is stabilized by the six strong `sigma` donors (`"H"_3"C":^(-)` is a strong base and nucleophile, and thus an excellent electron-donating group).

Apparently, the trigonal prismatic shape is a result of a so-called second-order Jahn-Teller distortion.