Further Studies of the Isomeric 1,2,7- and 1,3,6-Re₂Cl₅(PMe₃)₃ Compounds

New studies of compounds containing Re2Cl5(PMe3)3 molecules have been carried out on products prepared by one-electron oxidation of Re(II)−Re(II) compounds as well as by one-electron reduction of Re(III)−Re(III) species. The action of PhI·Cl2 on Re2Cl4(PMe3)4 in 2:1 mole ratio, in the presence of free PMe3, gives red 1,3,6-/1,2,7-Re2Cl5(PMe3)3 (1) containing two isomers in its unit cell. It was also shown that some additional 1,3,6-Re2Cl5(PMe3)3, isolated as its 1/2CH2Cl2 solvate (2), is always present in the reaction product. The reaction of the quadruply bonded complex [(n-Bu)4N]2Re2Cl8 with PMe3 in propanol at room temperature leads to 1,2,7-Re2Cl5(PMe3)3·(n-Bu)4NCl (3). Heating a dichloromethane solution of compound 3 results in pure 1,2,7-Re2Cl5(PMe3)3. All molecules are characterized by a Re25+ core with a σ2π4δ2δ* bond of order 3.5 and Re−Re distances within the range 2.210−2.227 Å. Crystal data are as follows: for 1, monoclinic space group P21/c, a = 14.936(5) Å, b = 8.8206(8) Å, c = 34.29(1) Å, β = 90.77(2)°, V = 4517(2) Å3, Z = 8; for 2, monoclinic space group P21/n, a = 8.907(1) Å, b = 16.112(1) Å, c = 16.683(3) Å, β = 94.751(6)°, V = 2385.9(5) Å3, Z = 4; for 3, triclinic space group P1, a = 8.911(2) Å, b = 10.686(2) Å, c = 10.979(3) Å, α = 101.12(2)°, β = 106.82(2)°, γ = 91.29(2)°, V = 978.5(4) Å3, Z = 1.