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

Reaction of the activated mixture of Re-2(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-tetrapho sphadecane (hptpd) yields a mixture of (d/l)- and meso-[{Re-2(mu-OMe)(2)(CO )(6)}(2)(mu,mu'-hptpd)] 1. The diastereomers can be easily separated by sel ective dissolution of d/l-1 in benzene, and give clearly distinguishable H- 1- and P-31-NMR spectra, The fluxional behavior of d/l-1 in solution has be en studied by variable-temperature H-1- and P-31-{H-1}-NMR spectroscopy. Th e crystal structures of both d/l- and meso-1 have been determined. Both mol ecules consist of two {Re-2(mu- OMe)(2)(CO)(6)} moieties which are bridged by the two P-CH2-CH2-P moieties of the hptpd ligand. Whilst the molecules o f meso-1 possess crystallographic i-symmetry, those of d/l-1 do not have an y crystallographic symmetry. These diastereomers therefore give clearly dis tinguishable Raman spectra in the solid state, Reaction of tris[2-(diphenyl phosphino)ethyl]phosphine (tdppep) with the activated mixture affords the c omplex [{Re-2(mu-OMe)(2)(CO)(6)}(mu,eta(2)-tdppep)] 2, and the analogous re action involving bis[2-diphenylphospinoethyl)phenylphosphine (triphos) give s [{Re-2(mu-OMe)(2)(CO)(6)}(mu,mu', eta(3)-triphos){Re-2(CO)(9)}] 3 and [{R e-2(mu-OMe)(2)(CO)(6)}(mu,eta(2)-triphos)] 4. (C) 1999 Elsevier Science S.A . All rights reserved.