Coordination-Driven Salamo-Salen-Salamo-Type Multinuclear Transition Metal(II) Complexes: Synthesis, Structure, Luminescence, Transformation of Configuration, and Nuclearity Induced by the Acetylacetone Anion

Acetate‐bridged binuclear Co(II) and Ni(II) complexes, [Co2(L)(μ‐OAc)(EtOH)] (1) and [Ni2(L)(μ‐OAc)(EtOH)] (2) were synthesized via the reaction of a new bis(salamo)‐like ligand with two different metal(II) acetates. X‐ray single crystal diffraction analyses showed that two metal(II) ions (Co or Ni) occupy two sets of N2O2 cavities, respectively. The acetate group bridges the two metals, and the ethanol oxygen atom participates in the coordination. Furthermore, UV–vis titration experiments clearly indicated that the complexation between H3L and M(II) ions leads to the 1:2 complexes [(L)M2]+ through a highly synergistic process. Bond valence sum (BVS) calculations exhibited that the Co(II) and Ni(II) ions are divalent. Secondly, the ligand H3L highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) gap analysis and surface electrostatic potential were theoretically analyzed by theoretical calculation (density functional theory), and the reactivity of M(II) ions and the ligand in the complex formation process was demonstrated. Finally, the microscopic properties of the complexes were deeply understood through the calculation of the weak intramolecular interactions and the unstressed regions outside the complexes.

Experimental and computational studies of two binuclear Co(II) and Ni(II) bis(salamo)‐like complexes

Yan,

La,

et al. 2023

Anion‐Modulated Construction of Two Novel Tetra‐ and Hepta‐Nuclear Ni(II) Salamo‐Type Clusters: Comparison of the DFT Calculations and Weak Interaction Analyses

Zhang,

Zheng

et al. 2024

Two novel tetra‐ and hepta‐nuclear Ni(II) salamo‐type clusters, [Ni4(L)2(μ2‐Cl)2(μ3‐OH)2(EtOH)2]⋅4CH2Cl2 (1) and [Ni7(L)3(μ3‐OEt)2(μ3‐OH)6(EtOH)2] (2), were constructed by modulating different anions (Cl− and NO3−). X‐ray crystallographic researches revealed that cluster 1 is a tetranuclear cluster consisting of a symmetric binuclear structure in which chloride ions are involved in coordination. Although cluster 2 consists of seven Ni(II) ions, three deprotonated (L)2− parts, two μ3‐ethoxy groups, six μ3‐OH− anions, and two coordinated ethanol molecules, in which it is quite rare for a large number of water molecules to be deprotonated to participate in the bridging of the cluster due to the alkaline environment. TEM electron scanning displayed the distinct shapes. Comparison of DFT calculations revealed that cluster 2 is less chemically reactive and more kinetically stable, which is in accordance with the analytical results of weak interactions, where the stronger weak interaction forces were presented, the more stable the molecule is. Finally, a comparative analysis of UV–Vis, IR, and fluorescence spectra were carried out.

Exploring the Differences in Self‐Assembly Behavior, Structure, and Properties of Two Novel Pentanuclear Zinc (II) Salamo‐Type Complexes Possessing Solvent Effect

Zheng,

Tuo,

Zhang

et al. 2024

A salamo‐type biscompartmental ligand was successfully prepared. On this basis, two novel pentanuclear zinc (II) salamo‐type complexes possessing solvent effect were self‐assembled successfully with different zinc (II) salts: [Zn5(L)2(μ‐OAc)2(CH3COCH3)] (1) and [Zn5(L)2(μ‐OAc)2(CH3CN)] (2). Complex 1 contains two fully deprotonated (L)4− units, five Zn(II) atoms, two coordinating acetate anions, and one coordinating acetone molecule. The zinc (II) atoms are all in a slightly distorted triangular bipyramidal geometrical configurations. Complex 2 consists of two fully deprotonated (L)4− units, five zinc (II) atoms, two coordinating acetate anions and a coordinating acetonitrile molecule. The different structures of the self‐assembling complexes may be attributed to various solvent effects applied in the self‐assembly. As a result, the acetate anions are involved in bridging coordination, thereby expanding the distance between secondary building units (SBUs). In addition, polar nonprotonic solvents, especially acetonitrile and acetone molecules, were involved in the coordination process. Finally, the reaction sites and intermolecular interactions were further discussed by MEP, IRI, and Hirshfeld surfaces, and their fluorescence properties were explored.