The Influence of β‐diiminato Ligands on As4 Activation by Cobalt Complexes

In a systematic study of the activation of As₄, 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 L⁰) and two with Me substituents (β‐diketiminates L³ and L¹). In the reaction with As₄, different dinuclear products (LCo)₂As₄] (LM=L⁰ ( 1 ), L¹ ( 2 ), L³ ( 3 )) were isolated, with all showing differently shaped Co₂As₄] 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 (L³Co)₂As₃] ( 4 ). All products were comprehensively characterized by single‐crystal X‐ray diffraction, FD‐MS, and ¹H NMR spectroscopy. A rational explanation for the different reactivity is also proposed and DFT calculations shed light on the nature of the highly flexible Co₂As₄] cores.