Why magnesium alkoxide is called complex as it don't consist any transition element?

1 Answer
Jul 28, 2017

Magnesium alkoxides are called complexes because they often exist as complex "clusters" of the alkoxide.

Explanation:

Alkoxide ions are good bridging ligands, that is, they can form bonds to two or more metal ions.

You see this, for example, in the dimer of #"FeCl"_3#

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where #"Cl"# atoms act as bridging ligands between the two #"Fe"# atoms.

Thus, four magnesium methoxide units combine in solution to form cubic structures of #["Mg"_4("OCH"_3)_8"(CH"_3"OH")_8]#.

Tetramer
(Adapted from [ RSC ] Publishing - Royal Society of Chemistry)

The diagram shows only the #"Mg"# atoms (blue) and the #"O"# atoms (red).

One of the #"OCH"_3# groups from each #"Mg"("OCH"_3)_2# is at a corner of the cubic structure, and the second is outside the cube.

Two methanol molecules are also coordinated to each #"Mg"# atom.