Osmiumkomplexe vom Halbsandwichtyp mit Oximen, Iminen und Azavinylidenen als Liganden

Abstract

Osmium Complexes of the Half‐Sandwich Type with Oximes, Imines, and Azavinylidenes as LigandAzavinylideneosmium complexes of the general composition [(arene)Os(NCRR)(L)]X (L = PMe3, PMetBu2, PiPr3) have been prepared by two methods. The first one uses the hydrido compound [C6H6OsHI(PMetBu2)] (2) and oximes HONCRR as starting materials and proceeds via the oxime complexes [C6H6OsH{N(OH)CRR}(PMetBu2)]PF6 (10, 11) as intermediates. They react with Al2O3 with elimination of water to give the final products 6–9. The second method starts with the dichloro‐ or diiodoosmium(II) compounds [(arene)OxX2(PR3)] (14, 16, 19, 21; arene = C6H6, 1,3,5‐Me3C6H3i R = Me, iPr) which upon treatment with HN = CPh2 or imine derivatives XNC(R)Ph (X = Li, SiMe3) afford the azavinylidene complexes 13b, 18, 23, 33. In the reactions with HNCPh2, the corresponding imine complexes [(arene)OsX(NHCPh2)‐(PR3)]X (15, 17, 20, 22) are formed as the primary products. Whereas nucleophilic addition of H– and CH3— to the N=C carbon atom of [C6H6Os(NCPh2)(PMetBu2)]+ (6) gives the imidoosmium(II) compounds [C6H6Os(NCRPh2)(PMetBu2)] (24, 25), the reaction of [C6H6Os(NCPh2)(PiPr3)]PF6 (13 b) with LiAlH(OtBu)3 yields the hydrido(imino) derivative [C6H6OsH(NHCPh2)(PiPr3)]PF6 (26). The bis(azido) complex [C6H6Os(N3)2(PiPr3)] (27), which is prepared either from 13 b or [C6H6OsI2(PiPr3)] (14) and NaN3, undergoes a [3 + 2] cycloaddition reaction with C2(CO2Me)2. Two isomeric (triazole)osmium compounds 28, 29 have been isolated. Treatment of [C6H6Os(NCRPh)(PiPr3)]PF6 with HX (X = O2CCF3) leads to addition of the acid to the OsN bond and, for R = Ph (13 b), by subsequent elimination of HX to the formation of a five‐membered metallaheterocycle 31. The X‐ray structural analysis of [C6H6Os(NCPh2)(PMetBu2)]PF6 (6) reveals an allene‐like arrangement of the ligands and substituents around the OsNC unit.