Halogen Bonding Involving I2 and d8 Transition-Metal Pincer Complexes

We systematically investigated iodine–metal and iodine–iodine bonding in van Koten’s pincer complex 19 modifications changing substituents and/or the transition metal with a PBE0–D3(BJ)/aug–cc–pVTZ/PP(M,I) model chemistry. As novel tool for quantitative assessment of bond strength these complexes we used local mode analysis, originally introduced by Konkoli Cremer, complemented NBO Bader’s QTAIM analyses. Our study reveals major electronic effects catalytic activity M–I–I non-classical three-center complex, which is involved oxidative addition molecular iodine I2 to center. According our investigations charge transfer from σ* antibonding orbital I–I changes 3c–4e character bond, leads weakening strengthening metal–iodine M–I facilitating this way metal. The can be modified substitution at different places metals, both bonds. also modeled original how solvents polarity influence bond. results provide new guidelines design specific strengths introduce vibrational analysis as an efficient assess complexes.