John C. Bailar, Jr. - Father of Coordination Chemistry

John C. Bailar, Jr. - Father of Coordination Chemistry

John C. Bailar, Jr. - Father of Coordination Chemistry

Biography & contributions

John C. Bailar, Jr. [John Christian Bailar, Jr.] was born on May 27, 1904 – died on October 17, 1991. He is referred to as the father of American coordination chemistry.Bailar received Priestley Medal from the American Chemical Society. He also identified one of the important concepts in organic chemistry called ‘isomerism’.

Coordination chemistry is the study of compounds formed between metal ions and other neutral or negatively charged molecules. The coordination chemistry was pioneered by Nobel Prize winner Alfred Werner. Coordination compounds are formed between a metal ion and a molecule with one or more unshared electron pairs, called a ligand.

Coordination chemistry of Cu2+ ion

Copper sulfate when it dissolved in water, produces the pale-blue [Cu(H2O)6] 2+ ion.

CuSO4.5H2O + H2O → [Co(H2O)6] 2+ + SO42-

The Cu2+ ion of copper sulfate is unique in that the addition of other ligands results in the replacement of only four water molecules.

For example, when dissolved in ammonia the deep-blue [Co (NH3)4(H2O)4]2+ ion is produced. This reaction serves as a qualitative test for the copper (II) ion.

CuSO4.5H2O + 4NH3 → [Co(H2O)2(NH3)4]2+ + SO42-

A similar reaction occurs with ethylenediamine, since ethylenediamine is bidentate, each ethylenediamine replaces two water molecules.

CuSO4.5H2O + 2en → [Cu(H2O)2(en)2] 2+ + SO42-

When dissolved in 12 M of HCl, the [CuCl4]2- ion is produced, which has physical properties like yellow in color and has square planar geometry.

CuSO4.5H2O + 4Cl- → [CuCl4]2- + SO42-

Addition of NO2 - to [Cu(H2O)6] 2+ ion results in the formation of a green solution which probably contains the [Cu(NO2)4]2- ion.

Coordination Chemistry of Fe2+ (Ferrous) Ion

One of the most commonly encountered ferrous salts is ferrous sulfate hexahydrate. Ferrous sulfate hexahydrate is pale-green in color and dissolves in water to give pale green solutions.

However, the ferrous ion is readily oxidized to the ferric ion by atmospheric oxygen, and 3 solutions slowly turn yellow due to this oxidation. The ferrous ion has an affinity for amine ligands. Addition of 1,10-phenanthroline results in the formation of red-orange [Fe(phen)3]2+, which serves as a qualitative test for the presence of the ferrous ion.   

The cyanide ions in this ferrocyanide ion, [Fe(CN)6]4- are very tightly bound and therefore the compound is not toxic. Several of the other transition metal ions will produce a precipitate with the ferrocyanide ion.

For example, the mixing of Fe3+ and [Fe(CN)6]4- produces a blue precipitate known as Prussian blue.


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