Oxo-rhenium(V) complexes with analogs of bis(diphenylphosphino)ethane

Compounds of the types ReOCl3(L–L) and ReOCl2(OEt)(L–L) with bis(diphenylphosphino)ethene (dppen) and bis(diphenylphosphino)ferrocene (dppf) were prepared by reacting the diphosphine with ReOCl3(OPPh3)(Me2S). The ReOCl3(L–L) compound with bis(diphenylarsino)ethane (dpae) was prepared similarly. Crystallographic work on ReOCl3(dppen) and ReOCl3(dpae) confirmed the approximate octahedral environment of the metal and the presence of a Cl ligand trans to the Redouble bond; length as m-dashO bond. The ReOCl2(OEt)(L–L) compounds contain a transOdouble bond; length as m-dashRe-OEt unit. The visible spectra of both types of compounds include a two-component d–d absorption pattern originating from the spin-allowed excitation of a d electron from the interaxial d orbital in the equatorial plane to the empty dxz and dyz orbitals. For ReOCl2(OEt)(dppf), these bands are masked by strong transitions taking place in the ferrocene moiety. The absorptions of the other systems are not greatly displaced compared to the similar dppe compounds, a small decrease in the transition energy being noted for the dpae complex.