Jahn-Teller Switching of a Redox-Active Nickel(III) Center in a Homoleptic Thiolato Metalloligand Environment.

Treatment of nickel(II) nitrate with the iridium(III) metalloligand -[Ir(apt)] (apt = 3-aminopropanethiolate) gave the trinuclear complex [Ni{Ir(apt)}](NO) ([](NO)), in which the nickel center has a formal oxidation state of +III. Chemical or electrochemical oxidation and reduction of [](NO) generated the corresponding trinuclear complexes [Ni{Ir(apt)}](NO) ([](NO)) and [Ni{Ir(apt)}](NO) ([](NO)) with one-electron oxidated and reduced states, respectively. Single-crystal X-ray crystallography revealed that the nickel center in [](NO) is situated in a highly distorted octahedron due to Jahn-Teller effect, while the nickel center in each of [](NO) and [](NO) adopts a normal octahedral geometry. Crystals of [](NO)·2HO are dehydrated on heating while retaining their single-crystallinity. The dehydration induces temperature-dependent dynamic disorder of the Jahn-Teller distortion at the nickel(III) center, which is largely quenched upon rehydration of the crystal.