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

Abstract

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.