Carben‐analoge Amidoosmium‐Komplexe mit OsN‐Doppelbindung: Synthese, Struktur und Reaktivität von [(Mes)Os(=NHR)(PiPr3)]PF6

Abstract

Carbene‐Type Amidoosmium Complexes with an OsN Double Bond: Synthesis, Structure and Reactivity of [(Mes)Os(=NHR)(PiPr3)]PF6*The reaction of [(Mes)Os(PiPr3)Cl2] (1) (Mes1,3,5‐C6H3Me3) with primary amines RNH2 (RPh, Me, Et) in acetone/water (1:1) gives, after addition of KPF6, the amidoosmium(II) complexes [(Mes)Os(=NHR)(PiPr3)]PF6 (2–4) in 60–80% yield. From 1 and Et2NH, the chloro(hydrido)compound [(Mes)1‐OsH(PiPr3)Cl] (5) is formed. The X‐ray structural analysis of 2 reveals that the geometry around the osmium atom is trigonalplanar (with the midpoint of the mesitylene ring as one coordination site) and that the OsN distance of 1.923(4) Å is in agreement with an OsN double bond. Thermolysis of 4 (REt) at 165°C leads to the formation of the aldimino(hydrido)osmium complex [(Mes)OsH(NHCHMe)(PiPr3)]PF6 (6) by β1‐hydride migration from the NCH2 carbon atom to the metal atom. Protonation of 3 (RMe) with HCl gives the amine complex [(Mes)Os(NH2Me)(PiPr3)Cl]PF6 (7), whereas on treatment of 3 and 4 with CD3NO2 the deuterated derivatives [(Mes)Os(=NDR)(PiPr3)]PF6 ([D1]‐3, [D1]‐4) are almost quantitatively formed. Compound 2 (RPh) reacts with KOtBu by proton abstraction and phosphane elimination to give the dinuclear imidoosmium complex [(Mes)2Os2(μ1‐NPh)2] (8).