Solvent-driven self-assembly of two novel di- and tetra-nuclear Cu(II) bis(salamo)-based complexes

• Published in: Journal of molecular structure 2023-02, Vol.1274, p.134554, Article 134554
• Main Authors: Zhang, Jian, Wei, Yu-Xin, Niu, Hao-Ying, Dong, Wen-Kui
• Format: Article
• Language: English
• Subjects: Bis(salamo)-based ligand; Counteranion influence; DFT studies; Hirshfeld surfaces analyses; Solvent-driven self-assembly
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2022.134554

•Solvent-driven self-assembly of two novel homopolynuclear Cu(II) complexes 1 and 2 were synthesized and characterized structurally.•The influence of the various solvent molecules and the counteranions make it form tetra-nuclear dimerization structure in complex 2, where two [Cu2(HL)Cl] metallized ligand units were bridged by two μ2-chloride ions.•DFT calculations, ESP studies and Hirshfeld surfaces of complexes 1 and 2 were investigated. Two novel di- and tetra-nuclear Cu(II) complexes, [Cu2(HL)Cl2(MeOH)]·MeOH (1) and [Cu4(HL)2Cl2(μ2-Cl)2]·4EtOH·H2O (2) (where H3L= bis(salamo)-based ligand) have been synthesized, and structurally characterized by elemental analysis, infrared and electronic absorption spectroscopy. The molecular structures of complexes 1 and 2 were defined by using single crystal X-ray diffraction experiment. The structural results indicated that complexes 1 and 2 have a close comparable [Cu2(HL)Cl2] unit in the unit cell where the ligand acts as a two-compartmental species chelating the metal ions Cu1 and Cu2. However, in complex 2, the [Cu2(HL)Cl2] complexes are paired in a centrosymmetric fashion to form a tetra-nuclear arrangement, connected by μ2-bridging chlorides. The observed different nuclearity is likely induced by the different solvent molecules used in the syntheses, methanol and ethanol in complexes 1 and 2, respectively. A methanol molecule participates in coordination of complex 1, while ethanol species in complex 2 is rather distant from one of the Cu(II) ions (ca 2.82 Å). The molecular frontier orbitals HOMO and LUMO of the complexes were analyzed by DFT calculations, and the results showed that the energy gaps of complexes 1 and 2 are particularly small compared to H3L, which may be caused by the combination of the orbitals of the central atoms and the donor atoms. The reaction sites of the ligand H3L with the metal Cu(II) were analyzed by ESP studies, and the results showed that the experiments were in agreement with the theory. Finally, Hirshfeld surfaces analyses were performed to quantitatively show various weak interactions of complexes 1 and 2. Two novel homopolynuclear Cu(II) complexes [Cu2(HL)Cl2(MeOH)]·MeOH (1) and [Cu4(HL)2Cl2(μ2-Cl)2]·4EtOH·H2O (2) from a new bis(salamo)-based ligand H3L have been synthesized and characterized structurally. [Display omitted]