[CopperSmurf]

There's this really cool reaction where PtCl₂(NH₃₂ (if not Cl, it can also be Br or I) can be distinguished as either trans for cis just by reacting it with thiourea, there the thiourea replaces the halogen and makes the complex have a 2+ charge.

Anyways, is this reaction named? I've been told that there's a "trans effect" involved where the thiourea is supposed to react really fast, but it sounds sketchy since it's "experimental". I'd like to know more about the inorganic chemistry behind it. Does anyone here know/heard of this? Just curious this time.

[Ligander]

I'd like to know more about the inorganic chemistry behind it. Does anyone here know/heard of this? Just curious this time.

 It's my homework for tomorrow(in fact today). It is given that in these two reactions you get two very dissimilar compounds that are not isomeres. It is given also that chloride-ion and thiourea both has more strong trans-effect than ammonia, and thiourea is stronger than chloride.
 
 So the first substitution for both cis- and trans-platinum is substitution of ammonia.

 Then in cis-isomer the second nitrogen of thiourea substitutes the second(and last) ammonia of Pt because it is kinetically much more favorable reaction than substitution of chloride that is in trans-position to thiourea ligand.

 In trans-platinum the second nitrogen of thiourea is not capable of substituting the second ammonia because  thiourea's "nipper" is very short to do this. So what occurs is the substitution of ammonia by second molecule of thiourea.

IMHO IMHO IMHO 

[AWK]

http://en.wikipedia.org/wiki/Cisplatin
http://books.google.pl/books?id=qnRkjATn0YUC&pg=PA10&lpg=PA10&dq=Kurnakov+test&source=bl&ots=oZM3ADsA2M&sig=1pxwjGaKLVKzMwl73AFzxy_jass&hl=pl&ei=2QVUS7abE9L4_Aak96CrBQ&sa=X&oi=book_result&ct=result&resnum=8&ved=0CD8Q6AEwBw#v=onepage&q=Kurnakov%20test&f=false

[Ligander]

Yes, I've made a mistake. In trans-platinum the first substitution is of chloride 

[EtherBunny]

I believe you are talking about the Kurnakov test. Try this article
http://www.platinummetalsreview.com/pdf/pmr-v20-i4-126-130.pdf

or google the article title "Il’va Il’ich Chernvaev’s Research J J
on the Platinum Metals"

On the 3rd page it gives the reaction mechanism for cisplatin and transplatin and thiourea it also states why thiourea substitutes all of the ligands in the cis isomer but only substitutes two of the ligands in the trans isomer