We have synthesized and characterized a series of bis-(phenanthroline)Cu(i) complexes of interest as redox mediators for dye-sensitized solar cells. This study led to the discovery of intriguing anagostic interactions between the hydrogen atom and the copper center as evidenced by X-ray diffraction studies on a single crystal. Remarkably, an anagostic interaction was found between a H atom of a methyl group and a copper site.