Chromium(VI) Bisimido Dichloro, Bisimido Alkylidene, and Chromium(V) Bisimido Iodo N‐Heterocyclic Carbene Complexes

Reaction of CrCl2(N-tBu)2 with 1,3-dimethylimidazol-2-ylidene (IMe), 1,3-dimethyl-4,5-dichloroimidazol-2-ylidene (IMeCl2), 1,3-di(2-propyl)imidazol-2-ylidene (IPr), 1,3-dimesitylimidazol-2-ylidene (IMes) and 1,3-bis(2,6-(2-Pr)2C6H3)imidazol-2-ylidene (IDipp) yields the corresponding N-heterocyclic carbene (NHC) adducts CrCl2(IMe)(N-tBu)2 (1), CrCl2(IMeCl2)(N-tBu)2 (2), CrCl2(IPr)(N-tBu)2 (3), CrCl2(IMes)(N-tBu)2 (4) and CrCl2(IDipp)(N-tBu)2 (5).

Likewise, reaction of CrCl2(N-2,6-(2-Pr)2C6H3)2 and CrCl2(N-adamantyl)2 with IMes yields CrCl2(N-2,6-(2-Pr)2C6H3)2(IMes) (6) and CrCl2(N-adamantyl)2(IMes) (7), respectively. Reaction of CrCl2(N-tBu)2 with the bidentate NHCs 1-R-3-(1-(2-LiO-C6H4))imidazol-2-ylidene yields the corresponding pentacoordinated Cr (VI) complexes CrCl2(1-R-3-(1-(2-O-C6H4))imidazol-2-ylidene)2C6H3)2(IMes) (R = 2,4,6-(CH3)3C6H2, 8), (R = tBu, 9), (R = 2-phenyl-C6H4, 10).