The invention relates to a method for producing urethanes or ureas or mixtures of urethanes and ureas by oxidative carbonylation of organic amines in the presence of carbon monoxide, oxygen and a catalyst, where the catalyst used is a transition metal complex containing the structural feature: [Mn+(O˜N˜O)2−](n−2)+(L)m(Z−)n−2 and the method is carried out under halogen-free reaction conditions. The invention further relates to transition metal complexes containing said structural feature and also to the use of such transition metal complexes as catalysts in the production of urethanes or ureas or mixtures of urethanes and ureas.