Rhenium(I) methoxo carbonyl complexes containing tetraphosphine or triphosphine ligands; Facile separation and X-ray crystallographic studies of d/l- and meso-[{Re2(μ-OMe)2(CO)6} 2(μ,μ′-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetra- phosphadecane)]

Abstract

Reaction of the activated mixture of Re2(CO)10, Me3NO and MeOH with a 1:1 mixture of rac (d/l)- and meso-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (hptpd) yields a mixture of (d/l)- and meso-[{Re2(μ-OMe)2(CO)6} 2(μ,μ′-hptpd)] 1. The diastereomers can be easily separated by selective dissolution of d/l-1 in benzene, and give clearly distinguishable 1H- and 31P-NMR spectra. The fluxional behavior of d/l-1 in solution has been studied by variable-temperature 1H- and 31P-{1H}-NMR spectroscopy. The crystal structures of both d/l- and meso-1 have been determined. Both molecules consist of two {Re2(μ-OMe)2(CO)6} moieties which are bridged by the two P-CH2-CH2-P moieties of the hptpd ligand. Whilst the molecules of meso-1 possess crystallographic i-symmetry, those of d/l-1 do not have any crystallographic symmetry. These diastereomers therefore give clearly distinguishable Raman spectra in the solid state. Reaction of tris[2-(diphenylphosphino)ethyl]phosphine (tdppep) with the activated mixture affords the complex [{Re2(μ-OMe)2(CO)6}(μ,η 2-tdppep)] 2, and the analogous reaction involving bis[2-diphenylphospinoethyl)phenylphosphine (triphos) gives [{Re2(μ-OMe)2(CO) 6}(μ,μ′,η3-triphos){Re 2(CO)9}] 3 and [{Re2(μ-OMe)2(CO)6}(μ,η 2-triphos)] 4. © 1999 Elsevier Science S.A.