The paramagnetic dirhenium compounds of stoichiometry Re2Cl5(PMe3)3have been prepared from the reactions of Re2Cl4(PMe3)4with Cl2(g) or with Phl·Cl2. Two isomers have been isolated and their structures determined. In terms of a numbering system to be explained in the text, in one isomer, l,3,6-Re2Cl5(PMe3)3(1), the two PMe3ligands that are coordinated to a Re atom are trans to one another, while in the other isomer, l,2,7-Re2Cl5(PMe3)3(2), the phosphines are cis. Attempts to convert the 1,2,7-isomer to the 1,3,6-isomer have been unsuccessful. A third compound, 1,3,6-Re2Cl5(PEt3)3(3) was isolated from the reaction between Re2Cl4(PEt3)4and Ph4P2. Pertinent crystal data are as follows: for 1, monoclinic space group C2/c, a = 13.157 (2) Å, b = 12.033 (2) Å, c = 28.197 (4) Å, β = 92.84 (1)°, V = 4459 (1) Å3, Z = 8; for 2, monoclinic space group P21/c, a = 8.973 (2) Å, b = 8.752 (1) Å, c = 28.691 (7) Å, β = 90.21 (2)°, V= 2253 (1) Å3, Z = 4; for 3, a = 11.589 (5) Å, b = 14.795 (4) Å, c = 17.942 (6) Å, β = 97.73 (3)°, V = 3048 (3) Å3, Z = 4. © 1990, American Chemical Society. All rights reserved.