Synthesis of Bis(triphenylphosphine)copper(I) borohydride, (Ph3P)2CuBH4
Yes, CuSO4·5H2O with PPh3 in ethanol at 80ºC until dissolution of the copper compound. Then, addition of NaBH4 and extraction with CHCl3.
Yes, exactly as Laura said. after the extraction with CHCl3 the product can be precipitated by addition of EtOH
Even if there is a difference in the oxidation number, synthesis is still possible? As in, the complex to be synthesized is copper (I) but the copper in the reagent is in the form of copper (II).
Thank you for the reply.
In fact, the reducting agent is the NaBH4, but in anycase it is a redox reaction.
No, not in this case: the NaBH4 is added after the reduction has already occurred. In the first reaction step, a copper(I) sulfate complex (that, to the best of my knowledge, hasn't been isolated nor characterized) is formed. During the second step of the reaction there is just an exchange between BH4- (which in fact is found as it is in the final product) and the sulfate.In this reaction NaBH4 is not the reducing agent.
(1) you can buy it in good quality (just google, I think Aldrich sells it, but also some chinese companies)
(2) you can start with a Cu(II) salt, such as the sulfate or the acetate, even the chloride should work. However, the purification/work up might be a little tedious. Depending on your experimental setup, either the phosphine or the borohydride will act as reductant.
(3) S. Lippard and colleagues have reported the Xral structure of this complex in 1967, and they describe a reasonable procedure to get the complex in good quality.
Journal of the American Chemical Society 89:15 July 19, 1967, pp. 3990, and
Transition Metal Borohydride Complexes. II. The Reaction of Copper(1) Compounds with Boron Hydride Anions, S. J. LIPPARD, D. A. UCKO, Inorg. Chem., 7, pp. 1051 (1968). This procedure is based on the original recipe by Italian chemists, you will find it in the refs..
In case you do not have access to those journals, fire me an e mail.
Cu(II) is reduced to Cu(I) by NaBH4. For full set of equations see below:
Peter is right in is answer, and the reductant depends on the reaction conditions: I was referring to the conditions reported by Laura. In this case, you can detect phosphin oxide in the reaction mixture in an almost colourless solution before the addition of NaBH4. The oxygen probably comes from the water (copper sulfate pentahydrate).
The triphenylphosphine oxide is only seen by a poor experimentalist .... it is due to aerial oxidation of triphenylphosphine in solution. All the reduction of Cu(II) to Cu(I) is done by borohydride which is oxidised to hydrogen and diborane. The only other potential reductant present is ethanol at the crystallisation stage but it does not actually act in this manner in this case. Look at the original report by Karen Bommer and Jerry Morse.
Caselli .... give it up ..... you are badly in error on this problem.
Dear Stephen,
I have read only today your post. I think your attitude is rather arrogant and not really scientific. This is supposed to be a research gate, where problems are discussed on a scientific ground and not a social network. So, unless you are not really sure that people like H.J. Gylsing and G.J. Kubas are poor experimentalists, I suggest you a more careful reading of the literature. You will find something really interesting about the reduction of Cu(II) salts to Cu(I) by organophpsphines here:
Gysling, H. J. and Kubas, G. J. (2007) Coordination Complexes of Copper(I) Nitrate, in Inorganic Syntheses, Volume 19 (ed D. F. Shriver), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470132500.ch19
If you don’t have access to this publication, please feel free to contact me.
No, it can be prepared form Cu(II)Cl2 because NaBH4 is used which will result in a fast reaction Copper(II) chloride can be easily reduced to cuprous chloride.
I know it can be done, because that was a fairly standard undergraduate lab when I was at university (I didn't keep my lab manuals, so I can't give you a reference). I can't say for sure if the triphenylphosphine acts as a reducing agent before the borohydride is added, but I will point out that the colourless species formed prior to the addition of the NaBH4 is more suggestive of a copper(I) compound than a copper(II) compound.
The borohydride is not needed as the reducing agent- refluxing copper(II) chloride in ethanol with triphenylphosphine will give [(Ph3P)CuCl]4. The reaction with borohydride is just metathesis.
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