The Influence of β‐diiminato Ligands on As(4) Activation by Cobalt Complexes

In a systematic study of the activation of As(4), three [LCo(tol)] (L=β‐diiminato) complexes have revealed different steric and electronic influences. 2,6‐Diisopropylphenyl (Dipp) and 2,6‐dimethylphenyl (dmp) flanking groups were used, one of the ligands with H backbone substituents (β‐dialdiminate L(0)) and two with Me substituents (β‐diketiminates L(3) and L(1)). In the reaction with As(4), different dinuclear products [(LCo)(2)As(4)] (LM=L(0) (1), L(1) (2), L(3) (3)) were isolated, with all showing differently shaped [Co(2)As(4)] cores in the solid state: octahedral in 1, prismatic in 2, and asterane‐like in 3. Thermal treatment of 3 leads to the abstraction of one arsenic atom to yield [(L(3)Co)(2)As(3)] (4). All products were comprehensively characterized by single‐crystal X‐ray diffraction, FD‐MS, and (1)H NMR spectroscopy. A rational explanation for the different reactivity is also proposed and DFT calculations shed light on the nature of the highly flexible [Co(2)As(4)] cores.