Addition of Carbenes to an Osmium(VI) Nitride Complex

Abstract

AbstractA series of osmium(VI) nitride complexes containing 8‐quinolinolato ligands, [OsVI(N)(X‐Q)2Cl] (X = H, 5‐Cl, 5‐NO2, 2‐Me; 1a–d), have been synthesized by reaction of HX‐Q with [nBu4N][OsVI(N)Cl4] in the presence of 2,6‐dimethylpyridine. The ν(Os≡N) stretches of these compounds occur at 1056–1075 cm–1, and are within the range (1050–1120 cm–1) found for most osmium nitride species. The structure of 1d has been determined by X‐ray crystallography. The osmium center adopts a distorted octahedral geometry, and the two quinolinolato ligands are cis to each other. The three N atoms are in a facial arrangement, and the Os≡N bond distance is 1.644(6) Å. Complex 1c readily reacts with the carbene precursors bis(1,3‐dialkylimidazolidin‐2‐ylidene) (LR2; R = Me, Et, or CH2Ph) to produce the osmium(IV) azavinylidene species, [OsIV(N=LR)(NO2‐Q)2Cl], which are derived from the formal addition of the carbenes LR to OsVI≡N. The structure of [OsIV(N=LEt)(NO2‐Q)2Cl] (2b) has been determined by X‐ray crystallography. The osmium center has a distorted octahedral geometry in which the facial arrangement of the three N atoms is retained. The Os(1)–N(5) distance of 1.875(6) Å is rather long and, together with the rather acute Os(1)–N(5)–C(19) angle of 133.8(5)°, indicates that there is no significant multiple‐bond character in the Os(1)–N(5) bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)