The increasing amounts of CO2 liberated by anthropogenic sources, like by combustions of fossil resources lead to raising temperatures and their devastating consequences for the climate. Therefore increasing effort is taken to not only prevent its release but also to use it as a starting material for synthetically valuable materials. One approach is the electrochemical reduction of CO2 to hydrocarbons with metallic Cu-electrodes. Current setups lack stability and selectivity to enable an industrial application. In addition there is no uniform mechanism to explain the complex product distribution. We investigate the reactivity of well-defined copper(I)-complexes towards CO2 and CO to prepare potential CO2 reduction intermediates. This enables the step by step investigation of the reaction pathway and the isolation of potential key intermediates. The obtained information can be used for a better understanding of the process on the electrode and consequently improve the electrolysis itself.