1 Unraveling the regioselectivity of odd electron halogen bond formation using electrophilicity index and chemical hardness parameters Prasanta Bandyopadhyay, Soumyadip Ray and Md. Motin Seikh* a Department of Chemistry, Visva-Bharati, Santiniketan-731235, West Bengal, India Supporting Information Contents 1. Figure S1: Fukui functions of CF 2 Cl 2 , CFCl 3 , CHF 2 Cl and CHFCl 2 …….2 2. Table S1: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon...ClComplexes. ..........4 3. Table S2: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon... OCl Complexes. ..........6 4. Table S3: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon...NO Complexes. ..........8 5. Table S4: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon...OH Complexes. ..........10 6. Table S5: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon...PhComplexes. ..........12 7. Table S6: BSSE and ZPE corrected Interaction energy (ΔE, kcal mol -1 ); Bond length (Å), total van der Waal radii of complexation atoms radii (Å), Bond angle () and coordinates of optimized complexes for Freon...PhComplexes at M06-2X-D3/6-311++G(d,p) level. ..........16 Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is © the Owner Societies 2019