Iridium

Iridium catalysts are made from either Ir(III) acetate or IrCl3.xH2O, the latter being used as precursor for many ligand Ir complexes (COD, Ph3P, ...). Ir(III) acetate is made by reacting iridium metal with barium peroxide in the presence of EtOH/HOAc at very high temperatures. To make Ir(III) chloride hydrate salts, iridium metals is fused with NaCl under an atmosphere of Cl2 at very high temperature, and the cake is dissolved in water. The Ir salt is precipitated by addition of NH4Cl and treated with aqua regia. Reducing this solution in volume will give you IrCl3.xH2O

Overview of possibilities:




Reference: PB Kettler. Platinum Group Metals in Catalysis: Fabrication of Catalysts and Catalyst Precursors. Org Proc Res Dev 7 (2003) 342-354


I agree there are easier precious metals to start playing with For sources, it might be possible to check out specialized gold and silver dealers. They also sell platina and palladium, and may have access to iridium, rhodium and ruthenium. These metals are used in the electronics industry as well, and you can find companies specialized in recuperation of the precious metals from old electronic equipment. Drawback is you often have to order no less than 1 kg, but if you have a chemical company, this clearly is the way to walk.

The price I quoted is around one year old. Indeed, prices of the precious metals fluctuate wildly, but I think that the price of iridium still will be something like that.

With the ruthenium I have, I also tried the method conc. HCl + NaClO3. Someone on usenet:sci.chem told me, but it did not work at all, despite the stories about ruthenium reacting violently or almost explosively with HCl/NaClO3. I got a lot of ClO2 and some Cl2, so indeed I could get explosions , but still completely undissolved Ru metal. I suspect that this method also does not work with iridium.

Someone else on usenet:sci.chem (Farooq) told me to use an alkaline solution of NaClO and boil the solution with the ruthenium powder in it. That worked like a charm. Within minutes, the powder was dissolved. However, this method does not work with iridium as stated by multiple people on other forums (e.g. the dutch chemieforum).

[Edited on 14-1-06 by woelen]

I have read that book front to back many times Magpie, but there exists abundant typographical errors (like any other Ammen book, good hands on experience, but bad editing :p) so I wouldn't put too much emphasis on that procedure when later on he talks about fusing it with potassium hydroxide and nitrate in zirconium crucible and then dissolving the fusion in water leaving IrO2 as a powder which is then dissolved in aqua regia and precipitated with ammonium chloride. IIRC, iridium is the most corrosion resistant pure metal known to man.

Neutrino, I personally would call Johnson Matthey or Alfa Aesar (a subsidiary of the former) and inquire about it, $200/troy ounce sounds a little low to me but I imagine it would be in that ballpark. You can buy off of ebay, but you'll pay probably the same or more and you won't have a guarantee about purity. Cheapest thing would be to get a powder, and definitely easiest when it comes to dissolving it.

Oh, eclectic, I have no idea how you plan to fabricate yourself a ring out of it using an arc furnace but I'm interested in hearing your idea nonetheless. I'm thinking you'll have to use an e-beam furnace to keep it molten (since at those temperatures removing the heat source=instantaneous solidification b/c of loss to radiation) and the mold hot enough to prevent instant chilling. Additionally, what type of mold would you use? I'm guessing sintered magnesia since graphite and SiC are out of the question because you'll get iridium carbide. Anyways, U2U me, I'd like to discuss it

garage chemist, this statement "Iridium begins to oxidise in air at 700°C forming volatile IrO3.
For working with hot iridium, inert gas atmosphere or vacuum must therefore be used." goes against the information found (courtesy Johnson Matthey) here: http://www.noble.matthey.com/product/detail.asp?article=34

I always thought iridium behaved more like the oxidation-resistant platinum than osmium and ruthenium (which both form volatile, poisonous oxides, some @ room temperature).


And from the conflicting reports of what dissolves it and what doesn't (and the limited number of us that actually have any and aren't just speculating) it would seem that the jury is out on what works best in an aqueous environment.