Spectral, crystallographic, theoretical, and catalytic activity studies of the PdII complexes in different coordination modes of benzoylthiourea ligand

Abstract

Syntheses of neutral monodentate dichloro bis[N‐(diethylcarbamothioyl)‐4‐fluorobenzamido-κS] palladium(II), [PdIICl2(LH-κS)2] and anionic bidentate bis[N‐(diethylcarbamothioyl)‐4‐fluorobenzamido-κ2O,S] palladium(II), [PdII(L-κ2S,O)2] complexes of N‐(diethylcarbamothioyl)‐4‐fluorobenzamide (LH) ligand is reported. While [PdIICl2(LH-κS)2] was obtained by reaction between PdCl2 and LH in acetonitrile solution as a single crystal form, [PdII(L-κ2S,O)2] was formed recrystallization of [PdIICl2(LH-κS)2] in dichloromethane: ethanol solvent mixture as powder form. The PdII complexes were characterized by elemental analysis, FT-IR, 1H NMR, and 13C NMR spectral measurements. Furthermore, the molecular structure of [PdIICl2(LH-κS)2] was defined by single crystal X-ray diffraction, and the result obtained was also confirmed by spectral data. The optimized molecular geometry of the ligand and [PdIICl2(LH-κS)2] complex was obtained by density functional theory calculation at the B3LYP/6-311G(d,p) and LanL2DZ level of theory, respectively. We found that the optimized geometrical parameters agree very well with the experimental one. Therefore, we used the same theoretical level (B3LYP/LanL2DZ) for the [PdII(L-κ2S,O)2] which is a powder form, not a single crystal form. The energies of frontier molecular orbitals (EHOMO and ELUMO), energy band gap, and quantum molecular descriptors of the prepared compounds were calculated. Information about the site of chemical reactivity, charge density distribution, the size, and shape of the molecules was obtained by mapping with molecular electrostatic potential (MEP). NBO analysis was applied for the investigation of intra and inter-molecular bonding and conjugative interaction in molecular systems. The Mulliken and natural population analyses were used to predict positive and negative charges on every atom in the molecules. Hirshfeld surface analysis and 2D fingerprint plots were applied to visualize and quantify intermolecular interactions and packing modes in the supramolecular structure. The Coulomb interaction, dispersion, and total energy calculations were used to visualize and analyze the three-dimensional figures of the crystal lattice. Furthermore, the catalytic efficiencies of both palladium complexes have been confirmed in the Suzuki-Miyaura C-C reaction using a very low 0.01 mol% catalyst loading.