Bismuth Pyridine Dipyrrolide Complexes: a Transient Bi(II) Species Which Ring Opens Cyclic Ethers

Abstract

A family of group 15 M^III pyridine dipyrrolide complexes has been prepared and fully characterized; the reduction of these complexes was investigated with traditional strong metal reductants, which led either to over-reduction in the case of Mg and Zn or to ligand redistribution and "ate" complex formation when KC₈ was used. However, by utilizing organosilanes as soluble reductants, the ring opening and two electron reduction of thf solvent was observed with concomitant formation of Bi-C and Si-O bonds; this is an example of a main group complex that is capable of ring opening a cyclic ether in the absence of additional metal reducing agents. The proposed Bi^II intermediate in this mechanism could be trapped using the stable organic radical TEMPO.