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 t Bu 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 t Bu 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 t Bu NiOOCH] is decreased from 3 to 0.5, the deprotonated part of the precursor enters a complex reaction sequence with formation of [L t Bu Ni I (μ‐OOCH)Ni I L t Bu ]K and [L t Bu Ni(C 2 O 4 )NiL t Bu ]. 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.