S1 Supplementary Information for Photoinduced C-N Bond Cleavage in 2-Azido-1,3-Diphenyl- Propan-1-one Derivatives: Photorelease of Hydrazoic Acid Rodney F. Klima, Abhijit V. Jadhav, Pradeep N. D. Singh, Mingxin Chang, Christine Vanos, Jagadis Sankaranarayanan, Mai Vu, Nazarin Ibrahim, Elaine Ross, Shaun McCloskey, Rajesh S. Murthy, Jeanette A. Krause, Bruce S. Ault and Anna D. Gudmundsdóttir* List of Contents: 1. Preparation of Azides 1 and their precursors S2 2. Preparation of 9 S4 3. Figure S1 and Table S1-S6. X-ray Structure of 3b S7 4. Figure S2 and Table S7-S12. X-ray Structure of 1a S13 5. S 0 and TD-DFT for Azide 1b S16 6. T 1K of Azide 1b S22 7. T A Azide 1b S23 8. Transition State for C-N bond cleavage in azide 1b S24 9. Transition State for forming 1b-n from 1b S26 10. Nitrogen molecule S27 11. Nitrene 1b-n S28 12. Radical 4b and TD-DFT S29 13. Azide 1a & TD-DFT calculation for azide 1a S32 14. T 1K for azide 1a S38 15. T 1A for azide 1a S40 16. Transition State for C-N bond cleavage in azide 1a S41 17. Transition State for forming 2a from 1a S43 18. Nitrene 1a-n S44 19. Radical 4a & TD-DFT S45 20. Azide 1c S48 21. T A of 1c S50 22. T 1K of 1c S51 23. Transition State for C-N bond cleavage in azide 1c S52 24. Transition State for forming 1c-n from 1c S55 25. Figure S3: 1 H-NMR spectrum of 1b-d S56 26. Figure S4: 13C-NMR spectrum of 1b-d S57 27. Figure S5: 1 H-NMR spectrum of 8 S55 28. Figure S6: 1 H-NMR spectrum of 1a S59 29. Figure S7: 1 H-NMR spectrum of 5 S60