REACTIONS OF ORTHOMANGANATED ARYL KETONES WITH SO2 - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF A NOVEL 6-MEMBERED METALLOCYCLIC RING ANDA NEW ROUTE TO ARYL SULFONATES

SO2 inserts into the Mn-C bond of orthometallated derivatives of subst ituted acetophenones, benzophenone or 2-acetylthiophene to give comple xes 2 which have six-membered metallocyclic rings incorporating an S-s ulfinate group. The X-ray structural determinations of two examples of the new species 2 show the ring to be strongly puckered. Some of the complexes 2 undergo a facile conversion to a dimeric species 3, shown by an X-ray structure analysis to have been formed from two molecules of 2 by mutual displacement of a CO ligand from one Mn atom by an S=O group from the other molecule. This provides a six-membered Mn-S-O-Mn- S-O core to the molecule. Oxidative demetallation of the SO2-inserted species 2 with H2O2 gives the corresponding aryl-sulfinates or -sulfon ates.