The focus of this work is the development and synthesis of suitable complexes for light driven hydrogen generation. Effective molecular water reduction systems consist of a photosensitizer (PS) and a water reduction catalyst (WRC). There are two different systems for water reduction. In a multi-component system the PS and the WRC are separated. In contrast, in a one-component system the PS and the WRC are connected via an organic linker, allowing a vectorial electron transfer. In the context of this thesis, multicomponent- and comparable bimetallic one-component systems were synthesized.To generate the photoactive center, numerous iridium(III) complexes were synthesized. Sustainable catalysts based on ecologically harmless and inexpensive metals iron and cobalt were prepared. Futhermore, two new bimetallic iridium/iron and iridium/cobalt complexes were obtained. The synthesized molecular photocatalysts were characterized by an extensive investigation with conventional methods and tested for hydrogen generation. Based on the spectroscopic and catalytic results, the iridium-PS were studied for a ligand-activity correlation.The synthesized systems show a significant activity in light-driven proton reduction. In particular the non noble metal based catalysts show an activity, which compete with noble metal catalysts.The experimental results show the great potential of the synthetisized systems for catalyze hydrogen generation from water.