A new water soluble heterometallic polymeric complex [{(PTA)₂CpRu-μ-CN-1κC:2κ²N-RuCp(PTA)₂}-μ-{Au(CN)₄}₄]_n·2H₂O (1) is synthesized and characterized by single crystal X-ray diffraction. This complex self-assembles forming 3D polymeric structures with large scale hexagonal conformation. They also organize as 3D stacks of polymer sandwiches that can be exfoliated providing mono heterometallic-3D layers, as shown by electron microscopy. Regarding the polymer dynamics, quasi-elastic neutron scattering shows a transition from vibrational Debye–Waller behaviour to a more dynamically active state as a result of the loss of structural water molecules.