A series of mono- and dihydrido- as well as mono- and dimethylosmium(II) complexes containing [(mes)Os(CNR)] as a building block
摘要:
The dihydridoosmium(II) complexes [(mes)OsH2(CNR)] (7-10) were prepared in excellent yield from the dichloroosmium(II) precursors [(mes)OsCl2(CNR)] upon treatment with 10% magnesium amalgam in THF in the presence of ethanol. Under similar conditions, the methylisocyanide derivative [(mes)OsH2(CNMe)] (6) as well as the monohydrido compounds [(mes)OsH(X)(CNMe)] (11, 13) were obtained. The same methodology using [(mes)OsCl(C6H5)(CNR)] as the starting material was applied for the preparation of the hydrido(phenyl)osmium(II) complexes [(mes)OsH(C6H5)(CNR)] (19-23) which were also isolated in almost quantitative yield. Treatment of these complexes with HCl in CH2Cl2 at -78 degrees C led to the cleavage of the osmium-phenyl but not the osmium-hydride bond. Reactions of [(mes)OsCl2(CNR)] with MeLi/LiCl gave exclusively the dimethylosmium(II) compounds [(mes)Os(CH3)(2)(CNR)] (29-32) while the corresponding reactions with MeLi/LiI afforded a mixture of 29-32 and the monomethyl derivatives [(mes)OsI(Me)(CNR)] (26, 33-35). A cyclic carbeneosmium(II) complex 37 was obtained from [(mes)OsCl2(CNPh)] and MeLi/LiI followed by treatment with deactivated Al2O3. The etheneosmium(0) compound [(mes)Os(C2H4)(CNMe)] (38) was prepared from the dimethylosmium(II) precursor 29 and briefly investigated as starting material for photochemical C-H activation reactions. (C) 2000 Elsevier Science S.A. All rights reserved.