Iron and Cobalt Complexes with Thiacarborane Ligands

Reaction of tBuNC with nido-6-SB9H11 in the presence of Proton Sponge gives the nido-thiacarborane 7-tBuNH2-7,9-CSB9H9 (2) apparently via rearrangement of the initially formed nido-7-tBuNH2-7,8-CSB9H9 (1) isomer. Deprotonation of 2 gives the anion [nido-7-tBuNH-7,9-CSB9H9]− (3), which reacts with [CpFe(C6H6)]+ and [(C4Me4)Co(C6H6)]+ under visible light irradiation to give closo-metallathiacarboranes 1-Cp-4-tBuNH-1,2,4-FeSCB9H9 (4) and 1-C4Me4-4-tBuNH-1,2,4-CoSCB9H9 (5) in 70% yields. At 110 °C, 4 undergoes extrusion of one boron atom, giving the 11-vertex compound closo-1-Cp-3-B(OH)2-1,2,3-FeSCB8H8 (6, 44%). According to DFT calculations, this process is initiated by nucleophilic attack of amine. The structures of 2, 4, 5, and 6 were confirmed by X-ray diffraction.