Selective Transformation of Nickel-Bound Formate to CO or C-C Coupling Products Triggered by Deprotonation and Steered by Alkali-Metal Ions.

The complexes [L Ni(OCO-κ O,C)]M [N(SiMe ) ] (M=Li, Na, K), synthesized by deprotonation of a nickel formate complex [L NiOOCH] with the corresponding amides M[N(SiMe ) ], feature a Ni -CO core surrounded by Lewis-acidic cations (M ) and the influence of the latter on the behavior and reactivity was studied. The results point to a decrease of CO activation within the series Li, Na, and K, which is also reflected in the reactivity with Me SiOTf leading to the liberation of CO and formation of a Ni-OSiMe complex. Furthermore, in case of K , the {[K [N(SiMe ) ] } shell around the Ni-CO entity was shown to have a large impact on its stabilization and behavior.

Activation of Dioxygen at a Lewis Acidic Nickel(II) Complex: Characterization of a Metastable Organoperoxide Complex.

In metal-mediated O activation, nickel(II) compounds hardly play a role, but recently it has been shown that enzymes can use nickel(II) for O activation. Now a low-coordinate Lewis acidic nickel(II) complex has been synthesized that reacts with O to give a nickel(II) organoperoxide, as proposed for the enzymatic system. Its formation was studied further by UV/Vis absorption spectroscopy, leading to the observation of a short-lived intermediate that proved to be reactive in both oxygen atom transfer and hydrogen abstraction reactions, while the peroxide efficiently transfers O atoms.

The activation of sulfur hexafluoride at highly reduced low-coordinate nickel dinitrogen complexes.

The greenhouse gas sulfur hexafluoride is the common standard example in the literature of a very inert inorganic small molecule that is even stable against O2 in an electric discharge. However, a reduced β-diketiminate nickel species proved to be capable of converting SF6 into sulfide and fluoride compounds at ambient standard conditions. The fluoride product complex features an unprecedented [NiF](+) unit, where the Ni atom is only three-coordinate, while the sulfide product exhibits a rare almost linear [Ni(μ-S)Ni](2+) moiety.