Two chromium(II) acetate complexes with N-heterocyclic carbene (NHC) coligands.

Tetra-kis(μ-acetato-κ(2) O:O')bis-{[1,3-bis-(2,6-diiso-propyl-phen-yl)imidazol-2-yl-idene-κC (2)]chromium(II)} tetra-hydro-furan disolvate, [Cr(2)(C(2)H(3)O(2))(4)(C(27)H(36)N(4))(2)]·2C(4)H(8)O or [Cr(2)(OAc)(4)(IDipp)(2)]·2C(4)H(8)O (1), and tetra-kis-(μ-acetato-κ(2) O:O')bis-{[1,3-bis-(2,4,6-tri-methyl-phen-yl)imidazol-2-yl-idene-κC (2)]chromium(II)},{Cr(2)(C(2)H(3)O(2))(4)(C(21)H(24)N(2))(2)] or [Cr(2)(OAc)(4)(IMes)(2)] (2), were synthesized from anhydrous chromium(II) acetate [Cr(2)(OAc)(4)] and the corresponding NHC (NHC = N-heterocyclic carbene) in toluene as solvent. Both complexes crystallize in the triclinic system, space group P. The mol-ecular structures consist of Cr(2)(OAc)(4) paddle-wheels that carry two terminal NHC ligands. This leads to a square-pyramidal coordination of the chromium atoms.