The present invention relates to novel organometallic compounds which are phosphorescence emitters. Compounds of this type can be used as active components (=functional materials) in a series of different types of, application which can be classed within the electronics industry in the broadest sense.The compounds according to the invention are described by the formulae (I), (Ia), (II), (IIa), (V), (VII), (IX), (XI), (XIII) and (XV).