The Influence of beta-diiminato Ligands on As-4 Activation by Cobalt Complexes

摘要

In a systematic study of the activation of As-4, three [LCo(tol)] (L=beta-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 (beta-dialdiminate L-0) and two with Me substituents (beta-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 [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 [((LCo)-Co-3)(2)As-3] (4). All products were comprehensively characterized by single-crystal X-ray diffraction, FD-MS, and (HNMR)-H-1 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.