Synthesis, Structures, and Reactivity of Nickel Complexes Incorporating Sulfonamido-Imine Ligands

Nickel complexes incorporating sulfonamido-imine ligands [o-C(H)NDipp-C6H4NSO2(Ar)]− (Dipp = 2,6-iPr2C6H3; L1 where Ar = 2,4,6-Me3C6H2, L2 where Ar = 4-MeC6H4, L3 where Ar = 4-O2NC6H4) were synthesized and characterized. Reaction of L1Li with trans-[Ni(Cl)(Ph)(PPh3)2], NiBr2(THF)1.5, and NiCl2(Py)4 resulted in the formation of the nickel(I) complex L1Ni(PPh3) (1) and the four-coordinate nickel halides L1Ni(Br)(THF) (2) and L1Ni(Cl)(Py) (3), respectively. In contrast, reactions of less hindered L2Li and L3Li with NiBr2(DME) yielded the bis(sulfonamido-imine)nickel complexes (L2)2Ni (4) and (L3)2Ni (5). Alkylation of 2 with LiCH2SiMe3 afforded the neutral nickel alkyl L1Ni(CH2SiMe3) (6). The molecular structures of 1–5 have been determined by X-ray single-crystal analysis. DFT calculations revealed that 6 adopts a distorted square-planar geometry with one of the oxygen atoms of the sulfonyl group being bound to the nickel center.