Abstract
The development of synthetic approaches to ortho-carborane-based ligand systems is driven by the unique chemical and physical properties of this cluster. Introduction of the carborane moiety into the ligand framework enables fine tuning of its electronic and steric properties while enhancing the thermal and chemical stability of the resulting complexes. These features make carborane-containing ligands promising building blocks for the design of catalysts, functional materials, and coordination compounds with tailored properties. In this work, a series of ortho-carboranyl ligand systems was synthesized via a five-step synthetic route. The first stage involved the condensation of a hydrazone oxime with pyridine-carboxaldehyde. The resulting intermediate underwent an aza-Diels–Alder reaction followed by reduction of the carbonyl group. At the subsequent stage, a Finkelstein reaction afforded the corresponding halide derivative, which subsequently underwent nucleophilic substitution with ortho-mercaptocarborane to yield the target ligand systems. The synthesized compounds may serve as promising precursors for the rational design of organic luminophores and organometallic complexes intended for application in organic light-emitting diodes (OLEDs).