Abstract
This work investigates possible mechanisms and intermediates in the reactivity of p-toluenesulfonyl fluoride with a new bidentate N-heterocyclic carbene (NHC) nickel complex, ((Mes)NHC(2) (o)Xy)-Ni-(COD) (Mes = 2,4,6-trimethylphenyl, (o)Xy = ortho-xylyl, COD = cyclooctadiene). ((Mes)NHC(2) (o)Xy)-Ni-(COD) was synthesized from the corresponding bis-(imidazolium) salt precursor, [(Mes)NHC(2) (o)Xy]-[Br](2), and both were structurally characterized. ((Mes)NHC(2) (o)Xy)-Ni-(COD) reacts with 1 equiv of p-toluenesulfonyl fluoride to furnish ((Mes)NHC(2) (o)Xy)-Ni-(η(2)-SO(2)), HF, and 1/2 equiv of 4,4'-dimethylbiphenyl. ((Mes)NHC(2) (o)Xy)-Ni-(η(2)-SO(2)) was structurally characterized and has a unique side-on SO(2) coordination mode with a Ni-S-O angle of 60.49(5)°. DFT calculations of ((Mes)NHC(2) (o)Xy)-Ni-(η(2)-SO(2)) are consistent with a Ni-(II) center and an activated SO(2) fragment. DFT calculations also support an initial oxidative addition at either the S-F or S-C position, which have similar energetics.