A streamlined synthesis of extended thiophloroglucinol ligands and their trinuclear NiII3 complexes

Abstract

A protocol for the synthesis of trinucleating C₃-symmetric ligands based on a central meta-phenylene bridging 1,3,5-trimercaptobenzene (thiophloroglucinol) backbone has been established. The key compound turned out to be the trialdehyde obtained from the triple nucleophilic attack of dimethyldithiocarbamate at 1,3,5-tribromo-2,4,6-triformylbenzene. Reacting this trialdehyde with six equivalents of a primary amine results in the simultaneous dithiocarbamate cleavage and Schiff-base formation providing the extended thiophloroglucinol ligands H₃bertdien, H₆bert^Me, H₆bert^t-Bu₂, and H₆habbi. Reaction with Ni^II leads to the formation of the trinuclear Ni^II₃ complexes [(bertdien)Ni^II₃](X)₃ (X = BPh₄⁻, BF₄⁻), [(bert^Me)Ni^II₃], [(bert^t-Bu₂)Ni^II₃], and [(habbi)Ni^II₃], which are characterized spectroscopically, electrochemically, and crystallographically.