Redox-active catecholate complexes of rhodium hydrotris(pyrazolyl)borates

The complexes [Rh(CO)LTp′] {L = CO or PPh3, Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate} reacted with the ortho-quinone o-C6Cl4O2 (o-chloranil; 3,4,5,6-tetrachloro-1,2-benzoquinone) to give [Rh{C(O)OC6Cl4O}LTp′] (L = CO, 1; L = PPh3, 2). X-Ray structural studies on 2 reveal CO insertion into one Rh–O bond of a rhodium–catecholate ring. Loss of the inserted CO on UV irradiation (of 1) or thermolysis (of 2) gives [Rh(o-O2C6Cl4)LTp′] (L = CO 3 or …