Supporting Information for: Fe 5 Mo Cluster with Iron-Carbide and Molybdenum-Carbide Bonding Motifs: Structure and Selective Alkyne Reductions Chris Joseph, Subramaniam Kuppuswamy and Michael J. Rose* Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States . Contents Page Synthetic and experimental procedures. S2 – 3 Figures S1-S2. 1 H and 13 C{ 1 H} NMR spectra of 1a S4 Figure S3. IR spectrum of 1 S5 Figure S4. Cyclic voltammogram of 1 S5 Figures S5-S6. 1 H and 13 C{ 1 H} NMR spectra of 2 S6 Figure S7. IR spectrum of 2 S7 Figure S8. Cyclic voltammogram of 2 S7 Figures S9. Structure of 1 based on X-ray diffraction data S8 – 9 Figure S10. ORTEP diagram of X-ray crystal structure solution of 2 S10 X-ray experimental for 2 S11 Table S1. Crystal data and refinement parameters of 2 S12 Table S2. Selected bond distances for 2 S13 Table S3. Reactivity results from DPA reduction reactions S14 Figures S11-S12. IR spectra of various reaction mixtures related to DPA reduction reactions S15 – 16 Figure S13. 1 H NMR of reaction mixture resulting from TfOH addition to reduced form of 2 S17