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(tBu)Ni(OCO‐κ (2) O,C)]M(3)[N(SiMe(3))(2)](2) (M=Li, Na, K), synthesized by deprotonation of a nickel formate complex [L(tBu)NiOOCH] with the corresponding amides M[N(SiMe(3))(2)], feature a Ni(II)−CO(2) (2−) 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(2) activation within the series Li, Na, and K, which is also reflected in the reactivity with Me(3)SiOTf leading to the liberation of CO and formation of a Ni−OSiMe(3) complex. Furthermore, in case of K(+), the {[K(3)[N(SiMe(3))(2)](2)}(+) shell around the Ni−CO(2) (2−) entity was shown to have a large impact on its stabilization and behavior. If the number of K[N(SiMe(3))(2)] equivalents used in the reaction with [L(tBu)NiOOCH] is decreased from 3 to 0.5, the deprotonated part of the precursor enters a complex reaction sequence with formation of [L(tBu)Ni(I)(μ‐OOCH)Ni(I)L(tBu)]K and [L(tBu)Ni(C(2)O(4))NiL(tBu)]. The same reaction at higher concentrations additionally led to the formation of a unique hexanuclear Ni(II) complex containing both oxalate and mesoxalate ([O(2)C‐CO(2)‐CO(2)](4−)) ligands.