Systematic Experimental and Computational Studies of Substitution and Hybridization Effects in Solid-State Halogen Bonded Assemblies

Abstract

A quantitative assessment of the substituent, hybridization, and crystal-packing effects on the electronic, structural, and vibrational properties of halogen bonded systems is presented. Through a combined experimental and theoretical approach employing Raman spectroscopy, X-ray crystallography, and density functional theory, a series of solid-state iodobenzene and iodoethynylbenzene derivatives substituted with electron withdrawing groups (-F2, -(CF3)2, -F5, and -(NO2)2) and their complexes with two pyridine-based building blocks are characterized. Structural analysis via X-ray crystallography and density functional theory computations suggests that these 1:1 molecular assemblies are not only driven by halogen bonding, but also by other energetically competitive noncovalent interactions, such as π-stacking. The magnitude of the σ-hole localized around the C–I bond in the isolated halogen bond (XB) donors and the interaction strength in the complexes unambiguously depend on the nature of the substituents ...