Submitted by Brian Johnson / St. John's University/College of St. Benedict on Wed, 07/20/2011 - 11:51

We are significantly changing both our course and lab curriculum.  One of our goals is to break down barriers between inorganic, organic and biochemistry by treating similar topics in each at the same time rather than in three different courses.   For example, one of the lab courses focuses on the use of different types of chromatography used in the three fields.  To the point of this inquiry, I have been charged with development of a chromatography experiment that involves inorganic chemistry.  What I thought I would LIKE to do would be to use some sort of ion chromatography to purifiy ionic coodination compounds from each other (separate a coordination compound that is a 2:1 electrolyte  from a 3:1) or from other ionic compounds like NaCl.  For example, could students be given a mixture of a 3:1 electrolyte like [Co(NH3)6]Cl3 and NaCl and purify it by chromatography.  Ideally, students would also evaporate the solvent, prepare a solution of a known concentration of the coordination compound, and measure the conductivity of the solution as a way of establishing that the compound is consistent with a 3:1 electrolye and that it not longer has NaCl in it.   The use of conductivity (and possible uv-vis) to characterize ionic compounds will extend students' awareness of characterization techniques to situations other than those found in classic organic column chromatography.   

In order for this to work, the coordination compound must be relatively substitution inert so that it does not decompose on the column, or through prolonged exposure to water, or upon heating or other procedures to isolate the solid.  Because I would like to introduce  the students to conductivity as a characterization technique, I would like the students to be able to isolate the compound as a pure solid.  Is anybody aware of a published or home grown experiment that would work like this, or a column packing material that might do such a separation without needing to add other components to the eluent that would interfere with isolation of the coordination compound as a pure solid?  In Angelici, for example, ion chromatography is used to separate  [Cr(H2O)6-xClx] species based on overall charge; however varying concentrations of HCLO4 are used to force the species off of the column. Thus, this procedure can't be used if you wish to isolate the solid.

I would appreciate any suggestions you might have.  Certainyl you can reply to the forum.  If you have something that is homegrown that you may not be ready to share with everyone, you can also reply to me directly at

Thanks, Brian

Adam Johnson / Harvey Mudd College

I don't know anything about ion chromatography, butl, for inert, you can't go wrong with the classic Werner complexes! A number of them are known with both inner sphere and outer sphere halides, such as [Co(NH3)5Cl]Cl2 or [Co(NH3)6]Cl3.  These are classic preps;  I think they are in Angelici (not sure if they're in the update by Girolami).

I'd like to see this if you figure it out.  We do have an ion chromatograph in our teaching lab (its old and clunky, and we use it to quantitate halides in a seawater aquarium for our analytical course, but it would be cool to use it in my inorganic course too!).


Thu, 07/21/2011 - 11:05 Permalink
Kurt Birdwhistell / Loyola University New Orleans

We use an ion exchange column for the characterization of K3[Fe(oxalate)3].  You can quantify the amount of K and the amount of Fe in your sample using a dowex resin and a pH meter20.  Maybe not quite what you are looking for, but a form of ion chromatography for analysis.


If you would like details, I can send a description.

Fri, 07/29/2011 - 16:39 Permalink
Partha / Duquesne University
Several years ago, our department changed its UG curriculum to combine discipline specific labs into one, what we called 'integrated laboratory'. Similar to what Brian is talking about. For that course we used ion chromatography for CrCl3 in perchloric acid. The chlorides are substituted by water. The students separated different species and characterized them by UV-vis spectroscopy. The spectral features were used in calculating 10 Dq values. None of the compounds were isolated in the solid state. for that we used Dowex 50 resin. if you wish to get more information, email me
Mon, 08/15/2011 - 18:05 Permalink