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

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(II)3 complexes [(bertdien)Ni(II)3](X)3 (X = BPh4(-), BF4(-)), [(bert(Me))Ni(II)3], [(bert(t-Bu2))Ni(II)3], and [(habbi)Ni(II)3], which are characterized spectroscopically, electrochemically, and crystallographically.