Neutral oxorhenium(V) complexes with dithioether ligands of the general formula [ReOX3(RS[CHz]2SR)], X = C1, Br, R = nBu, Et, Bzl were synthesized. Ammonium perrhenate reacts in concentrated hydrochloric acid with dithiaalkanes (RS[CH2I2SR, R = nBu, Et, Bzl) dissolved in glacial acetic acid to give octahedral complexes of the type [Re-OCl,(RS[ CH,],SR)] ( l ac) . In concentrated hydrobromic acid, nBu-S(CH2jzS-nBu leads to the corresponding tri- bromo complex (2). The X-ray structure of 2 shows a distorted octahedron with facial coordination oi the bromide ligands. The sulfur atoms are cis coordinated to the terminal oxygen. Dissolution of l a (R = nBu) in methanol leads to the substitution of the chloride trans to the 0x0 ligand by a meth-oxy group. The resultant complex [ReOC12(MeO)(n-Bu-S[CH212S-nBu)] (3) is stable and can be isolated from methanolic solution, but changes to the p-0x0-bridged dirhenium complex p-oxobis[ dichloro(5,6-dithiadodecane)oxorhe- nium(V)] (4) when dissolved in other organic solvents. la reacts with an excess of benzenethiol by substitution of two chlorides to give the mixed-ligand complex bis(benzenethi0lato) chloro (5,8 -dithiadodecane) oxorhenium(V j (5a j . The related 4-methylbenzenethiolato complex 5b was synthesized starting from the p-0x0 complex 4. X-ray crystal structure determination of 5b shows the equatorial arrangement of the sulfur atoms. The trans position to the oxygen atom is occupied by a chloride ion. lntroduction Knowledge of the coordination chemistry of rhenium and technetium is of great importance for Lhc design of radiopharmaceuticals based on 18611 88-Re and 99m-Tc. Taking rhenium as a substitute for radioactive technetium, we particularly explored the coordination ability of thioether ligands at the metal oxidation state +5, +3, and