Ligand-Centered Redox-Assisted Synthesis of a Bis(imino)acenaphthene-Stabilized Tellurium(II) Dicationic Compound

The redox-active nature of the bis(imino)acenaphthene (BIAN) ligand enabled the formation of [(dipp-BIAN)TeCl2] (dipp = 2,6-diisopropylphenyl), compound 1, via two-electron transfer from the dianionic BIAN ligand to TeCl4, resulting in reduction of Te(IV) to Te(II). Treatment of 1 with 2 and 3 equiv of AgSbF6 resulted in the formation of Te(II) mono- and dicationic compounds 2 and 3, respectively. The effective Lewis acidity of compound 3 was assessed using the Gutmann–Beckett method. Reaction of 3 with Ph3PO afforded compound 4, featuring coordination of two Ph3PO units at the Te(II) dicationic center. Compound 3 was employed as a proof-of-concept Lewis acid catalyst for the hydrosilylation of p-methyl benzaldehyde. All the compounds were characterized using single-crystal X-ray diffraction, multinuclear nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, and absorbance spectroscopy.