Synthesis, Characterisation, Crystal Structure, DFT, and Hirshfeld Surface Study of a Slightly Distorted Tetrahedral Zn(II) Complex Based on Triphenylphosphanol

An intriguing novel complex, [ZnCl2(Ph3POH)2], containing two equivalents of triphenylphosphanol (Ph3POH), was synthesized by reacting anhydrous ZnCl2 with triphenylphosphine in methanol, yielding a dichlorobis(triphenylphosphanol)-zinc(II) complex with the chemical formula C36H32Cl2O2P2Zn. The synthesized zinc complex was fully identified by molar conductivity, magnetic susceptibility, FT-IR, UV-Vis spectroscopy, and single-crystal X-Ray Diffraction (XRD). The single-crystal X-ray diffraction study proves that the complex possesses a metal-to-ligand ratio of 1:2, with each Ph₃POH ligand coordinating to the Zn(II) center in an unidentate mode via its oxygen atom. Spectroscopic analyses, along with single-crystal XRD results, validated the mononuclear configuration of the Zinc(II) complex. Calculations were carried out utilizing Density Functional Theory (DFT) at the B3LYP/6-311G level for the ligand and the B3LYP/LANL2DZ level for the Zn(II) complex. These computations evaluated the kinetic stability and reactivity of the ligand and its zinc complex by measuring the HOMO-LUMO electronic energy levels and generating the Molecular Electrostatic Potential (MEP) map. The Natural Bond Orbital (NBO) analysis revealed that the charge on the zinc ion decreased from +2.0 e to +0.989 e upon complexation. According to the Hirschfeld surface study, measured over dnorm, shape index, and curvedness, the main intermolecular interactions contributing to crystal packing are H... Cl/Cl...H, C...H/H...C, and H... H.