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

Carbene‐Type Amidoosmium Complexes with an OsN Double Bond: Synthesis, Structure and Reactivity of [(Mes)Os(=NHR)(P i Pr 3 )]PF 6 * The reaction of [(Mes)Os(P i Pr 3 )Cl 2 ] ( 1 ) (Mes1,3,5‐C 6 H 3 Me 3 ) with primary amines RNH 2 (RPh, Me, Et) in acetone/water (1:1) gives, after addition of KPF 6 , the amidoosmium(II) complexes [(Mes)Os(=NHR)(P i Pr 3 )]PF 6 ( 2–4 ) in 60–80% yield. From 1 and Et 2 NH, the chloro(hydrido)compound [(Mes)1‐OsH(P i Pr 3 )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)(P i Pr 3 )]PF 6 ( 6 ) by β1‐hydride migration from the NCH 2 carbon atom to the metal atom. Protonation of 3 (RMe) with HCl gives the amine complex [(Mes)Os(NH 2 Me)(P i Pr 3 )Cl]PF 6 ( 7 ), whereas on treatment of 3 and 4 with CD 3 NO 2 the deuterated derivatives [(Mes)Os(=NDR)(P i Pr 3 )]PF 6 ([D 1 ]‐ 3 , [D 1 ]‐ 4 ) are almost quantitatively formed. Compound 2 (RPh) reacts with KO t Bu by proton abstraction and phosphane elimination to give the dinuclear imidoosmium complex [(Mes) 2 Os 2 (μ1‐NPh) 2 ] ( 8 ).