Exploring the coordination chemistry of O,N,O′-ligands modified by 2-thienyl-substituents to nickel

•The chemistry of the pyrazol-5-ol ligands 1 containing 2-thienyl groups was studied.•1 forms with Ni(OAc)2 and DMAP the complexes 4 [Ni(1-2H)(DMAP)x].•The position of the 2-thienyl group influences the geometry of the complexes.•The complexes we applied in the nickel-catalyzed hydrodehalogenation.

The coordination chemistry of 5-hydroxypyrazoline ligand class 1 modified by 2-thienyl substituents with Ni(OAc)2 and DMAP as co-ligand to form the nickel complexes 4 [Ni(1-2H)(dmap)x] was investigated. The complexes were characterized and investigated by various techniques, pointing out different complex geometries, octahedral vs. square planar, depending on the connectivity of the 2-thienyl substituent. In more detail, X-ray crystallography revealed an O,N,O′-coordination in which the ligand is planar and the other coordination sites on the nickel center are occupied by one or three DMAP co-ligands, respectively. Moreover, the complexes have been applied as precatalyst in nickel-catalyzed hydrodecyanation reactions.

Graphical abstractThe chemistry of the pyrazol-5-ol ligands 1 containing 2-thienyl groups was studied. 1 forms with Ni(OAc)2 and DMAP the complexes 4 [Ni(1-2H)(DMAP)x]. The position of the 2-thienyl group influences the geometry of the complexes. The complexes we applied in the nickel-catalyzed hydrodehalogenation.Figure optionsDownload full-size imageDownload as PowerPoint slide