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Adam R. Johnson, Harvey Mudd College
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cis and trans isomers in the teaching lab

Does anyone have good reliable syntheses for preparing both the cis- and trans- complexes of a square planar metal with the same ligands that I could use in the teaching lab?
I had 2 students try to make cis- and trans-platin this year, which you think would be easy, but the data are inconclusive.  I would especially like a prep that involves phosphines with different phosphorus environments so that I could show them cis/trans coupling constants.  But maybe not in the same experiment.

Basically, this is a plea from an early metal chemist for some help finding bulletproof late metal preps.   

Adam 

Nancy Scott Burke Williams, Scripps College, Pitzer College, Claremont McKenna College
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If you just want a mix of cis and trans complexes which can be chromatographically separated, Bob Pinnell wrote up the Pt(SEt2)2Cl2 cis/trans separation.  The synthesis is trivial.  
Maggie Geselbracht, Reed College
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Scott, do you have a reference for that?
Nancy Scott Burke Williams, Scripps College, Pitzer College, Claremont McKenna College
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Kauffman, George B.; Pinnell, Robert P.; Takahashi, Lloyd T.  "Separation of inorganic stereoisomers by adsorption chromatography. I. Nonelectrolytic geometric isomers of platinum(II)"    Inorg. Chem.  (1962),  1  544-50. 
Adam R. Johnson, Harvey Mudd College
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actually, two different preps would be cool.  I had a student dig up some old preps from the 1970s or so for cis and trans platin, but they were done on 100g scale or so.  smaller scale would be nice, and they didn't scale down well.
Kurt Birdwhistell, Loyola University New Orleans
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Adam,

You might try [Co(en)2Cl2] .  Obviously not any phosphines but beautiful colors green and purple.

There are Inorg. Synth. preps for both of these isomers.

Hmm, Maybe I will look for a dppe version of the above complexes.  

Kurt

Adam R. Johnson, Harvey Mudd College
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thanks for the suggestion.  I really would like to do a late metal with phosphines though, to see Pt satellites and the different 31P NMR signals.  That and we already have 2 Co labs, but I am thinking about nixing Co(en)3 for next year since it just takes too long.  I'll look and see what the preps for the cis- and trans- dichlorides looks like.

Adam