Nickel nitrosyl complexes in a sulfur-rich environment: The first poly(mercaptoimidazolyl)borate derivatives

The diamagnetic nickel mononitrosyl complexes (TmR)Ni(NO) (R = But, p-Tol) and (BmR)Ni(PPh3)(NO) (R = Me, But) have been readily prepared from Ni(PPh3)2(NO)Br and the appropriate Na(TmR) or Na(BmR) reagents, respectively. These species constitute the first nickel nitrosyl complexes supported by these ligand systems. An X-ray diffraction study of (Tmp-Tol)Ni(NO) confirmed its pseudo-tetrahedral geometry and the presence of a nearly linear nitrosyl ligand. In contrast, (BmMe)Ni(PPh3)(NO) can be best described as having a trigonal pyramidal geometry, a spatial arrangement unprecedented in nickel nitrosyl chemistry, which is facilitated by the disposition of the BmMe ligand and the presence of a weak intramolecular Ni⋯H–B interaction opposite to the apical triphenylphosphine ligand.

Graphical abstractThe first nickel nitrosyl complexes supported by bis- and tris(mercaptoimidazolyl)borate ligands, (BmR)Ni(PPh3)(NO) (R = Me, But) and (TmR)Ni(NO) (R = But, p-Tol), have been readily prepared and fully characterized using a combination of analytical and spectroscopic techniques. Whereas the TmR compounds are tetrahedral and contain linear nitrosyl ligands, the BmR derivatives are trigonal pyramidal and display bent NO groups.Figure optionsDownload full-size imageDownload as PowerPoint slide