Wikipedia talk:Featured article candidates/Rhodocene/archive1

"Protonated Rhodocene"

Thanks to EdChem, who sent me a PDF of: Fischer, E. O.; Wawersik, H. (1966). "Über Aromatenkomplexe von Metallen: LXXXVIII. Über Monomeres und Dimeres Dicyclopentadienylrhodium und Dicyclopentadienyliridium und Über Ein Neues Verfahren Zur Darstellung Ungeladener Metall-Aromaten-Komplexe" (in German). J. Organomet. Chem. 5 (6): 559–567.

I have read the whole article in German and here report the part on the synthesis of what the Wikipedia article calls "protonated rhodocene", cyclopentadienyl rhodium cyclopentadiene. The synthesis is described only very briefly, in the third paragraph on page 560. What follows is a rough, sentence by sentence translation. They report that they, like may others, wanted to make Rh(C₅H₅)₂ or Ir(C₅H₅)₂ by reduction of the higher oxidation state compounds. They used the blue solution of sodium dissolved in liquid ammonia as a reducing agent, as it had recently been used in their research group to isolate di(hexamethylbenzene)cobalt(0), and thus had proven itself an apparently ideal reducing agent for aromatic-metal-complexes.[their ref 6] The striking result is that one obtains large quantities of "cyclopentadienylrhodiumcyclopentadiene" (properly (η⁴-Cyclopentadiene)(η⁵-cyclopentadienyl)rhodium(I)), which leads to one to suspect that a primary (initial?) reduction could be followed by a proton addition via the solvent. Als auffallendes Ergebnis erhielt man dabei in grosseren Mengen Cyclopentadienylrhodiumcyclopentadien, was die Vermutung nahelegte, dass einer primaeren Reduktion eine Protonenaddition durch das LoesungsmitteI gefolgt sein koennte. They therefore sought another synthetic route which would use proton-free solvents or even avoid solvents all together.

They go on to use direct reduction with alkali metals and the rhodocenium or iridocenium salts. The experimental details of the mixed ligand Rh complex are not given in any further detail. Ruhrfisch _><>°^° 22:28, 6 February 2011 (UTC)

Thanks very much, Ruhrfisch - much appreciated. My recollection of "protonated" is clearly clouded, so I have redrafted the section to remove the term and bring the text in line with your summary. EdChem (talk) 23:40, 6 February 2011 (UTC)

You are very welcome - I just cleaned up my translation (made super and subscripts, fixed some typos, clarified a few things). Will look at the changes on Wiki next. Ruhrfisch _><>°^° 02:12, 7 February 2011 (UTC)