A contribution to the coordination chemistry of (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso): Synthesis, characterization, and DFT calculations of trans-[PtCl2(dmso-κS)(2-pyimiso-κN)

Abstract

Examples of coordination entities bearing (E)-N,N′-bis(heteroaryl)iminoisoindolines are scarce in the literature. This scarcity has prompted us to investigate the coordination chemistry of (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso), a polydentate ligand exhibiting three potentially coordinating nitrogen atoms. In this paper we report the synthesis, spectroscopic characterization and DFT calculations of trans-[PtCl2(dmso-κS)(2-pyimiso-κN)] (trans-1), which contains 2-pyimiso as a monodentate ligand. DFT calculations in the gas phase, using either B3LYP, M06 or PBE0 hybrid functionals along with the LACV3P∗∗ and LACV3P∗∗++ basis sets, have revealed that in trans-1, 2-pyimiso coordinates to Pt(II) through the 2-pyridyl group attached to the imine nitrogen atom. Solvation free energies of both cis- and trans-1 in acetonitrile were computed at the M06/LACV3P∗∗ level of calculation using the Poisson–Boltzmann solvation model. The ΔG298 value calculated for the cis–trans equilibrium of 1 in acetonitrile is −5.5kcalmol−1, which agrees with our 1H NMR data in acetonitrile-d3.