176544-55-1Relevant academic research and scientific papers
Conversion of OsH2(CO)(PPh3)3 to [OsH(CO)(PPh3)2L2]+ (L = pyridine, 4-tert-butylpyridine) by oxidation, hydride abstraction and protonation
Li, Lan,Belay, Yohannes,Gipson, Stephen L.
, p. 1937 - 1941 (1996)
Two bis(pyridine) analogues of the 2,2'-bipyridine complex [OsH(CO) (PPh3)2(bpy)] have been synthesized from the dihydride OsH2(CO)(PPh3)3 (1). Chemical or electrochemical oxidation of 1, even in the presence of excess pyridine, is an overall one-electron process. The oxidation is proposed to involve the reaction of radical cations with the starting dihydride to form a 1 : 1 mixture of the 17-electron complex OsH(CO)(PPh3)3 and the trihydride [OsH3(CO)(PPh3)3]+. Both oxidation of the 17-electron complex and reductive elimination of H2 from the trihydride cation, both accompanied by pyridine coordination, would give [OsH(CO)(PPh3)3(Py)]+. Reaction of this proposed intermediate with excess pyridine yields [OsH(CO)(PPh3)2(Py)2]- as the observed final product. This bis(pyridine) complex is also produced by hydride abstraction from 1 in the presence of pyridine and by protonation of 1 with HBF4 followed by reaction with pyridine. 4-Tertbutylpyridine participates in the same reactions. The pyridine complexes are very similar to the previously reported 2,2'-bipyridine complex except that they do not display the bipyridine-localized reduction or metal ligand charge transfer band. Their geometry is the same, with trans-oriented phosphines and cis-pyridines.
