195724-79-9Relevant academic research and scientific papers
Octamethyl-1,1′-diphosphachromocene: Its spin distribution and oxidation
Feher, Robert,K?hler, Frank H.,Nief, Fran?ois,Ricard, Louis,Rossmayer, Stefan
, p. 4606 - 4610 (1997)
Octamethyl-1,1′-diphosphachromocene ((Tmp)2Cr) was prepared from (Tmp)K and chromium dichloride in 81% yield. According to X-ray analysis, it has a distorted sandwich structure with the P atoms being bent away from chromium. Large 1H, 13C, and 31P NMR shifts established the similarity to chromocenes (S = 1) and negative spin on the ligands. The signal splitting and temperature-dependent 1H NMR data revealed that, on the ligand, the spin sits predominantly at the phosphorus and two carbon atoms. In the cyclic voltammetry, two oxidation steps and one reduction were visible. After chemical oxidation, [(TmP)2Cr]+[B(C6H5) 4]- was isolated in 65% yield. Its EPR spectrum is in accord with a S = 3/2 species. The 1H NMR spectrum resembled those of chromocenium ions. Its analysis and that of the temperature-dependent 1H NMR spectra indicated a rather uniform spin distribution within the ligands. It was concluded that, in any case, the phosphorus may release spin to neighboring molecules.
