Well‐defined binuclear Co(II) complexes: Synthesis, structure, characterizations and catalytic applications in cyanosilylation of various aldehydes under solvent‐free condition

We present here the well-defined two novel binuclear cobalt (II) [Co(H2L1)]2 and [Co(H2L2)]2 compounds. Binuclear cobalt (II) complexes (1−2) containing 1,1'-binaphthyl derived tetradentate (N2O2) donor ligands, namely 3,3-bis[((2,6-diisopropylphenyl)imino)methyl]-[1,1'-binaphthalene-2,2'-dioxodicobalt(II) and 3,3′-bis-[((2,6-diethyl-phenyl)imino)-ethyl]-[1,1']-binaphtyl-2,2'-dioxocobalt(II) complexes for the first time, were synthesized and isolated as shown in Scheme 1. Various spectroscopic techniques, including UV-Visible spectra, Magnetic susceptibility, Cyclic voltammetry, Elemental analysis, Mass spectrometry, and Single-crystal X-ray diffraction, were used to structurally characterize these binuclear cobalt(II) complexes. The binuclear cobalt (II) [Co(H2L1)]2 and [Co(H2L2)]2 complexes (1−2) were demonstrated excellent catalytic activity in the cyanosilylation reaction of various aryl aldehydes into value-added cyanohydrins at room temperature under solvent-free conditions.