A comparative study of the isomers of ReOCl3(PMe3)2 and ReOCl3(PEt3)2. The isolation and characterization of ReH7(PR3)2 and ReO(OEt)Cl2(PR3)2 (R=Me or Et) and the photoelectron spectrum of ReH7(PMe3)2

Abstract

The reactions of mer–trans-ReOCl3(PPh3)2 with PMe3 and PEt3 provide a route to the isomers fac–cis-ReOCl3(PR3)2 and mer–trans-ReOCl3(PR3)2 (R=Me or Et) which can be converted to ReH7(PR3)2 (R=Me or Et) in ca. 60% yield by reaction with LiAlH4 in THF and subsequent hydrolysis of the reaction mixtures. The properties of these heptahydrides have been examined, including studies of the remarkable stability of aqueous solutions of ReH7(PMe3)2 and the measurement of the gas-phase He(I) photoelectron spectrum of this complex. While the fac–cis and mer–trans isomers of ReOCl3(PR3)2 (R=Me or Et) do not convert to ReO(OEt)Cl2(PR3)2 upon reaction with ethanol, these ethoxides can be prepared by the reaction of mer–trans-ReO(OEt)Cl2(PPh3)2 with PMe3 and PEt3. The reactions of the isomers of ReOCl3(PMe3)2 with ethylamine, followed by the treatment of the reaction products with acetone, afford the salt [Me3PCMe2CH2C(O)CH3]ReO4. The compounds fac–cis-ReOCl3(PEt3)2, trans-ReO(OEt)Cl2(PMe3)2 and [Me3PCMe2CH2C(O)CH3]ReO4 have been structurally characterized by X-ray crystallography.