Dichroic, Dinuclear μ₂‐(η²‐NO)‐Nitrosoaniline‐Bridged Complexes of Rhenium of the Type [{(CO)₃Re(μ‐X)}₂ONC₆H₄NR₂] (X = Cl, Br, I; R = Me, Et)

Abstract

A series of unusual dinuclear μ2‐(η2‐NO)‐nitrosoaniline‐bridged complexes [{(CO)3Re(μ‐X)}2ONC6H4NR2] (X = Cl, Br, I; R = Me, Et) with dichroic properties have been synthesised by reaction of pentacarbonylhalogenorhenium(I) [(CO)5ReX] (X = Cl, Br, I) with the corresponding nitrosoaniline derivatives R2NC6H4NO (R = Me, Et). The deeply coloured solutions in CH2Cl2 show broad UV/Vis absorptions from 595 to 620 nm depending on the halogen bridges and N substituents. Single crystals of all six compounds exhibit a pronounced linear dichroism. The molecular structures have been determined by single‐crystal X‐ray analyses. All the compounds contain two face‐shared octahedra, with two halogens and one NO ligand as bridges. The NO ligand coordinates in a nonsymmetrical η2‐like fashion with N or O coordination to each Re centre. Therefore, the C‐nitroso group and the planar NC2 moiety of NR2 both lie almost exactly within the symmetry plane of the dinuclear complexes. These complexes belong to the novel and simple class of neutral dinuclear C‐nitroso complexes that include the rare, non‐assisted μ2‐(η2‐NO) ligand function and have only single halogen atoms in bridging positions.