Thermal versus photochemical pathways of a manganese 10-vertex metalladecaborane: [Nido-6-Mn(CO)₃B₉H₁₃][NMe₄]

The relationship between the thermal and photochemical reaction pathways of the 10-vertex metalladecaborane complex, [nido-6-Mn(CO)₃B₉H₁₃][NMe₄] (1), has been investigated. The reaction types observed included a nido-6 to nido-5 cage isomerization process and a nido-6 to hypercloso-metallaborane conversion through hydrogen loss and cage closure reactions. The particular reaction pathway observed was found to depend upon the reaction conditions employed. UV photochemical irradiation of 1 resulted in the formation of the hypercloso-[Mn(CO₃)B₉H₉][NMe₄] structure while the thermal reaction effected an isomerization process to form the nido-5-[Mn(CO)₃B₉H₁₃][NMe₄] complex. Varying the solvent, under certain conditions, also yielded cage degradation reactions. The spectroscopic and structural characterization of the products of these reactions included multi-nuclear NMR, including ¹¹B and 2D ¹¹B–¹¹B COSY NMR, FTIR, and UV–Visible methods. The X-ray crystallographic structures of the complexes [nido-6-Mn(CO)₃B₉H₁₃][NMe₄] (1) and [nido-5-Mn(CO)₃B₉H₁₃][NMe₄] (2) are also reported in this work.