This proposal seeks to investigate the spin-state and spin-crossover phenomena in metal-organic complexes using high-resolution single-crystal X-ray diffraction and Anomalous Dispersion Refinement (ADR) techniques. These phenomena are critical in fields like molecular electronics and data storage, yet current experimental techniques often lack the three-dimensional resolution needed for in-depth understanding. By utilizing ADR, we aim to resolve electron density distributions before and after a thermally induced spin-crossover, achieving unprecedented precision in the analysis of the electronic and structural changes involved. The experiment will focus on Ru and Ag-based metal organic complexes, and will combine X-ray Absorption Spectroscopy (XAS) with diffraction data to provide new insights into the interplay between spin states and structural dynamics.