Novel Chiral-at-Metal Pseudotetrahedral Ru(II) Complex of a Chiral Selenated Schiff Base: Synthesis, Characterization, Absolute Crystal Structure and Hirshfeld Surface Analysis

Abstract

A novel ruthenium(II) complex, [Ru(p-cymene)((R)-L)](PF₆) ((R)-1) of a chiral selenated Schiff base ligand, (2R)-BnSeCH₂CH(CH₃)N=CH-C₁₀H₈-2-OH ((R)-LH) is synthesized and characterized by elemental analysis, ¹H/¹³C{¹H} NMR and FTIR spectroscopy. The characterisation data of the complex, (R)-1 reveal that, the conjugate base ((R)-L) of the chiral ligand is found to be coordinated in a tridentate (Se, N, O^–) mode to the central Ru(II) ion. The resulting product contained a mixture of the two diastereomers of the complex containing two chiral centers, one at carbon and another chiral-at-metal. One of the diastereomers of the complex is obtained on recrystallization of the product into an orange-red crystalline compound. The absolute molecular crystal structure of this diastereomer is determined by single crystal X-ray diffraction. The crystal data revealed that the complex crystallizes in the orthorhombic crystal system in the space group P2₁2₁2₁. The bond parameters demonstrated that the complex has half-sandwich pseudotetrahedral geometry around the Ru(II) ion. The flack parameter (x = 0.06(3)) further confirms the presence of a single diastereomer in the crystalline sample of the complex, (R)-1. In the molecular crystals of the complex, there exists Se⋯F (3.206 Å), CH⋯O (2.00 Å) and CH⋯F (2.46 Å to 2.62 Å) type of intermolecular secondary bonding interactions resulting in supramolecular structure. The intermolecular interactions exhibited by the crystalline environment of the complex are evaluated by the Hirshfeld surface (HS) analysis.