Monomeric tungsten complexes with catechol coordinated bidentately as the monoanion [1,2-O,OHC 6H 4] − have been prepared by reacting WOCl 4 with catechol in diethyl ether solution. One equivalent of catechol leads to the formation of [W(O)Cl 3(O, HOC 6H 4)·O(C 2H 5) 2], while two equivalents of catechol leads to the formation of [W(O)Cl(O 2C 6H 4)(O,HOC 6H 4)·O(C 2H 5)2], for which the crystal structure has been determined. In the complex the tungsten atom is octahedrally coordinated to one oxo ligand [ d(WO) = 1.65(2) Å], one chloro ligand [ d(WCl) = 2.325(7) Å] and one chelating catecholate dianion, [1,2-O 2C 6H 4] 2− [ d(WO) = 1.91(1) Å and 1.95(1) Å], in a plane almost perpendicular to the tungsten-oxo bond. A chelating catechol monoanion, [1,2-O,OHC 6H 4] −, with the negatively charged oxygen atom [ d(WO) = 1.89(1) Å] trans to a catecholate oxygen atom and the hydroxy oxygen atom trans to the oxo ligand [ d(WO) = 2.35(2) Å], completes the inner coordination sphere. A diethyl ether molecule is strongly hydrogen-bonded to the hydroxy group with a short distance of 2.51(2) Å between the ether oxygen atom and the hydroxy oxygen atom.