Metalloporphyrin sulfido, selenido, and imido complexes: synthesis, characterization, and transfer reactions

Abstract

<p>Metalloporphyrins containing metal-oxygen multiple bonds have been the focus of numerous studies. In contrast, the chemistry of species containing multiple bonds to the heavier chalcogenides or the Group 15 elements is underdeveloped. In general, this has been the result of a lack of suitable synthetic precursors for the preparation of non-oxo containing derivatives;A new simple method for the preparation of early transition metal porphyrin halide complexes, starting from a porphyrin dianion and a metal halide species, provides a high yield route to metalloporphyrin halides of vanadium, molybdenum, titanium, and tungsten. Utilizing the molybdenum halide complex, (TTP)MoCl[subscript]2, we have found a number of synthetic routes for the preparation of the first terminal sulfido and selenido molybdenum porphyrins, (TTP)Mo=X (X = S, Se). The molybdenum chalcogenides may also be generated by treatment of (TTP)Mo(PhC≡CPh) with (TTP)Sn=X, formally an intermetal two-electron redox process mediated by sulfur or selenium atom transfer. In an analogous manner, treatment of (TPP)Sn=X (X = S, Se) with (TTP)Sn(II) results in the reversible exchange of a sulfur or selenium atom. For this Sn(IV)/Sn(II) exchange, we have found that the rate of selenium atom transfer is over 200 times faster than that of sulfur atom transfer;Employing early transition metal porphyrin halide complexes as precursors, we have also been able to prepare novel imido complexes of titanium and molybdenum porphyrins. In a reaction analogous to atom transfer, treatment of (TTP)Mo=NPh with (TTP)Ti(PhC≡CPh) results in complete imido group transfer to give (TTP)Mo(PhC≡CPh) and (TTP)Ti=NPh. This dissertation focuses on the synthesis, characterization, and transfer reactions of these sulfido, selenido, and imido metalloporphyrins.</p>