Halogen Bond Character in the Alkyl Halides

The quantity (I+s2), the sum of the ionicity and s hybridization, has been calculated from nuclear quadrupole coupling data for 24 alkyl halides. The ionicity has been estimated independently from calculated values of εx, the effective charge on the halogen. The average derived values of s2, the amount of s character in the hybrid halogen bonding orbital, are 13.6% for carbon-chlorine bonds, 8.6% for carbon-bromine bonds, and 1.8% for carbon-iodine bonds.