Rhenium oxytetrachloride is an inorganic compound with the chemical formula ReOCl<sub>4</sub>. It is a dark red solid.
Infrared and magnetic data indicate square pyramidal geometry.
Rhenium oxytetrachloride is prepared by reacting rhenium heptoxide with thionyl chloride. Initially a golden-brown complex of perrhenyl chloride with sulfuryl chloride, (ReO<sub>3</sub>Cl)<sub>2</sub>,SO<sub>2</sub>Cl<sub>2</sub> is gradually deposited. Upon prolonged contact, this rhenium(VII) complex redissolves with reduction to rhenium(VI). On vacuum evaporation of the thionyl chloride supernatant, or of the final solution after redissolution of the complex, the dark red rhenium oxytetrachloride is obtained.
It can also be prepared by heating rhenium pentachloride and dry oxygen in a sealed vessel at 180 ðC. Direct chlorination results in an impure product.
Rhenium oxytetrachloride is formed quantitatively by heating rhenium metal in sulfuryl chloride at 300 ðC.
Upon reaction with pyridine, an oxotrichlorobispyridinerhenium(V) complex is formed.