Talk:Prussian blue (color)

message: "(note: this is not in the public domain, even though it is on a .gov site)" ... wtf?
:The statement is both true (it's a private industry document, as noted by the copyright statement at the bottom of the page) which is provided by the U.S. government, but was not written by the U.S. government, so it is copyrighted) and irrelevant.  I've removed it. Chuck 19:30, 20 September 2005 (UTC)

message: I posted a correction to the structure of Prussian Blue and less than a day later someone else changed it back. Since there seems to be some confusion (and since whoever changed it back does appear to know a few things about chemistry), I’ll post this here first and give everyone a chance to respond before I re-edit the article. 
Prussian Blue is a cubic structure of Fe(II), Fe(III), and cyanide. In a perfect crystal of PB each Fe atom is coordinated octahedraly to six cyanide ligands, with Fe(III) coordinated to the carbon end of cyanide and Fe(II) coordinated to the nitrogen end. This structure would result in a net charge imbalance of –1 per formula unit. There are two ways that PB can adapt its structure to cope with this charge imbalance. First, it can incorporate alkali cations into the interstitial spaces of the lattice. Such cations are generally available during PB formation, since nearly all synthesis procedures involve the use of alkali salts like K3Fe(CN)6 or KCN. Second, it can randomly leave out cyanide ligands to correct the charge imbalance – this occurs to a large extent if an exotic synthesis procedure that doesn’t involve alkali cations is used, but will still occur to a smaller extent even if alkali cations are availale. If the PB is made in an aqueous solution (or simply left sitting out in air for very long) water will work its way into to lattice and coordinate to the Fe atoms where the cyanide ligands would have been. 
You often see people write the formula as something along the lines of Fe7(CN)18 in an attempt to make the charges balance, but that’s not correct – and if you think about it for a moment, it should be clear you can’t form PB’s classic simple cubic structure if you have seven Fe atoms to every six cyanide ligand. -April 4th, 2006
:I was the reverter back the formula back to hydrated Fe7(CN)18, although I expanded the section to explain the case further. This formula is what inorganic chemists accept PB per Andreas Ludi, who solved the structure.
:I also used to think that the formula was as you indicate, which would certainly make PB easier to explain to students.  You are referring to an expanded ReO3 structure - all metals octahedral with CN "rods" connecting them.  Some PB relatives like that may exist, but PB is not one of them, at least according to inorganic dogma.  PB is more complicated than the ReO3 motif - it is metal deficient.  Take a look at the Ludi's paper or Dunbar's review.  I realize that I possibly are being too dogmatic.  Hence my comment that PB might be whatever blue stuff crashes out when you mix Fe(III) and ferrocyanide.  Also, I agree with the implication of your comments - hydrated Fe7(CN)18 would have no ion-exchanging possibilities (unless one deprotonates Fe(III)-OH2 units, replacing H+ with Tl+ or Cs+).  I admit to not fully understanding this bit, and I assume that the "medical grade" PB, used to sequester Tl+ tends toward the formula that you indicate, with K+ in the framework.
Thank you for taking the time to explore this issue on the Talk page, yours--Smokefoot 15:59, 6 April 2006 (UTC)
replies: text: Thanks, I didnt know how to write "≤."--Smokefoot 01:51, 17 April 2006 (UTC)
replies: text: No problem, glad to be of help.149.43.x.x 06:19, 17 April 2006 (UTC)
thread_title:  Formula of Prussian Blue

message: If prussian blue is in fact used as a tool or gauge in metalworking, could someone add something about how it's used in that way in the article?  Someone following the link from Measuring tools and gauges will be frustrated if there's nothing in the article about it. Chuck 19:36, 20 September 2005 (UTC)
thread_title:  Tools and gauges? 

message: I've heard that the term Prussian Blue was used to refer to the residue of Zyklon-B left in Nazi gas chambers. Can anyone confirm this information? Is it worth adding to the article? Pburka 18:45, 1 October 2005 (UTC)
thread_title: Connection to [[Zyklon-B]]

message: Off topic material needs to go to a different page, reference by a dablink (See Wikipedia:disambiguation). I was going to do it myself, but the material (below) is too poorly written at this stage to use for a stub. -St|eve 21:52, 21 October 2005 (UTC)
thread_title:  Duo 

message: I assume the chemical was invented in Berlin, hence its name. Is this correct? Bastie 03:48, 13 November 2005 (UTC)
replies: text: Can I add ferriferrocyanide as another name? It's listed on paint, but I don't know if it's chemically identical. Njál 15:48, 23 December 2005 (UTC)
thread_title:  Name