A Series of MIICuII3 Stars (M = Mn, Ni, Cu, Zn) Exhibiting Unusual Magnetic Properties

Flexibility and lability of a phenyl ligand in hetero-organometallic 3d metal-Sn(iv) compounds and their catalytic activity in Baeyer-Villiger oxidation of cyclohexanone

The single compartmental Schiff base N,N'-ethylenebis(salicylaldimine) (H₂L) and [SnPh₂Cl₂] were utilized to synthesize heterobimetallic 3d metal-Sn complexes, the Co^IIISn^IV compound [{SnPhCl₂}(1κO²N²,2κO²-μ-L)(μ-OMe){CoPh}] (1), the Ni^IISn^IV compound [{SnPh₂Cl₂}(1κO²N²,2κO²-μ-L)Ni] (2) and the Cu^IISn^IV compound [{SnPh₂Cl₂}(1κO²N²,2κO²-μ-L)Cu] (3). Attempting to prepare the ethoxido bridged compound analogous to 1 (in ethanol) gives the phenylcobalt(iii) complex [Co(κO²N²)Ph(H₂O)] (1A). Single crystal X-ray structure analyses reveal that 1 is derived from an intermetallic (Sn to Co) phenyl shift and that 1A is a transmetallated product; in compounds 2 and 3, the phenyl groups remain coordinated to Sn^IV but one of the π rings interacts with the 3d-metal. Thus, while systems 1 and 1A show the lability of the phenyl ligand, 2 and 3 reveal its flexible nature. Theoretical DFT calculations demonstrate that the conceivable Ph group shift occurs in the oxidized Co^III intermediate [{Sn^IVPh₂Cl₂}(κO₂N₂-μ-L){Co^III(MeO)}] (5) rather than in the corresponding Co^II species [{Sn^IVPh₂Cl₂}(κO₂N₂-μ-L){Co^II(MeOH)}] (4). Their catalytic studies in the Baeyer-Villiger oxidation of cyclohexanone into ε-caprolactone with two different oxidants reveal that the sacrificial aldehyde method (with dioxygen/benzaldehyde) is better than that with aqueous H₂O₂ (30%). The effects of various reaction parameters such as solvent, catalyst amount, temperature, time and heating method were studied allowing the achievement of yields up to 83% with 89% selectivity.

Syntheses, crystal structures, magnetic properties and ESI-MS studies of a series of trinuclear CuIIMIICuII compounds (M = Cu, Ni, Co, Fe, Mn, Zn)

Six trinuclear CuIIMIICuII compounds (M = Cu, Ni, Co, Fe, Mn, Zn) derived from the Schiff base ligand, H2L (2 + 1 condensation product of salicylaldehyde and trans-1,2-diaminocyclohexane) are reported in this investigation. The composition of the metal complexes are [{CuIIL(ClO4)}2CuII(H2O)]·2H2O (1), [{CuIIL(ClO4)}{NiII(H2O)2}{CuIIL}]ClO4·CH3COCH3 (2), [{CuIIL(ClO4)}{CoII(CH3COCH3)(H2O)}{CuIIL(CH3COCH3)}]ClO4 (3) and isomorphic [{CuIIL(ClO4)}2MII(CH3OH)2] (4, M = Fe; 5, M = Mn; 6, M = Zn). Two copper(ii) ions in 1-6 occupy N2O2 compartments of two L2- ligands, while the second metal ion occupies the O(phenoxo)4 site provided by the two ligands, i.e., the two metal ions in both CuIIMII pairs are diphenoxo-bridged. Positive ESI-MS of 1-6 reveals some interesting features. Variable-temperature and variable-field magnetic studies reveal moderate or weak antiferromagnetic interactions in 1-6 with the following values of magnetic exchange integrals (H = -2JS 1 S 2 type): J 1 = -136.50 cm-1 and J = 0.00 for the CuIICuIICuII compound 1; J 1 = -22.16 cm-1 and J = -1.97 cm-1 for the CuIINiIICuII compound 2; J 1 = -14.78 cm-1 and J = -1.86 cm-1 for the CuIICoIICuII compound 3; J 1 = -6.35 cm-1 and J = -1.17 cm-1 for the CuIIFeIICuII compound 4; J 1 = -6.02 cm-1 and J = -1.70 cm-1 for the CuIIMnIICuII compound 5; J = -2.25 cm-1 for the CuIIZnIICuII compound 6 (J is between two CuII in the N2O2 compartments; J 1 is between CuII and MII through a diphenoxo bridge).

Construction of Zeolite-Like Cluster Organic Frameworks from 3 d-4 d/3 d-3 d Heterometallic Supertetrahedral Secondary Building Units: Syntheses, Structures, and Properties

Two zeolite-like cluster organic frameworks based on Cd-Cu/Mn-Cu heterometallic supertetrahedral secondary building units have been successfully constructed under solvothermal conditions, namely, Cu[Cd₄ Cu₆ (L)₄ (H₂ O)₁₈ ](Ac)₉ ⋅DMA⋅3 H₂ O (1), and Cu[Mn₄ Cu₆ (L)₄ (Ac)₃ (H₂ O)₁₂ ](Ac)₆ ⋅CH₃ CN⋅13 H₂ O (2), where H₃ L=2-(hydroxymethyl)-2-(pyridin-4-yl)-1,3-propanediol, Ac=CH₃ COO^- , DMA=N,N'-dimethylacetamide. Single-crystal X-ray structural analysis reveals that both 1 and 2 exhibit 3-dimensional zeolite-like architectures with similar 4-connected components, but possess definitely different topologies of diamondoid (dia) and uncommon lonsdaleite (lon), respectively. 1 and 2 represent the first cases of zeolite-like cluster organic frameworks containing Cd-Cu/Mn-Cu heterometallic supertetrahedral secondary building units. Furthermore, the magnetic properties and porous nature of 1 and 2 were also studied.

Details make the difference: a family of tetranuclear CuIIMnIII complexes with cube-like and double open cube-like cores

The "direct synthesis" approach, namely one-pot reaction of metal powders and ammonium salt with a methanol solution of a polydentate Schiff base (H₂L) formed in situ from salicylaldehyde and ethanolamine, has been successfully used for the preparation of the new heterometallic compounds [Cu₃Mn(L)₄(CH₃OH)₃]I₃ (1), [Cu₃Mn(L)₄(CH₃OH)₃(H₂O)]NCS·H₂O (2), [Cu₃Mn(L)₄(CH₃OH)(H₂O)_2.55]Br·0.45H₂O (3) and [Cu₃Mn(L)₄(H₂O)_3.4]BF₄·0.6H₂O (4). Crystallographic analysis revealed that 1-4 are based on the tetranuclear core {CuMn^III(μ₃-O)₄} where the metal centres are joined by the oxygen bridges of Schiff base ligands forming a cube-like arrangement. The novel heterometallic compound [Cu₃Mn(L)₄(CH₃OH)₃]₂[Mn(NCS)₄]·2CH₃OH (5) has been obtained by the "building block" approach using the reaction of [Cu(HL)₂] with manganese acetate and NH₄NCS in methanol. The crystal structure of 5 revealed the {CuMn^III(μ-O)₂(μ₃-O)₂} metal core which can be viewed as a double open cube. In spite of a similar {Cu₃MnO₄} atom set in the cores of 1-5, the complexes show rather different molecular structures and significantly differ by the number and combinations of coordinated CH₃OH/H₂O solvent molecules. Variable-temperature (2-300 K) magnetic susceptibility along with variable-field magnetization measurements of 1-5 showed a decrease of the effective magnetic moment value at low temperature, indicative of the antiferromagnetic coupling of medium size (-55 to -22 cm^-1). For these systems resembling a compressed prism the coupling constant in walls J₄ correlates with the averaged bonding angles in walls α: J₄vs. α develops approximately according to a straight line.

Chiral six-coordinate Dy(iii) and Tb(iii) complexes of an achiral ligand: structure, fluorescence, and magnetism

Two new chiral six-coordinate lanthanide complexes are obtained using an achiral ligand. Complex [Zn₃Dy] displays field-induced slow magnetization relaxation, while complex [Zn₃Tb] exhibits intense green photofluorescence and triboluminescence.

N-HO and N-HCl supported 1D chains of heterobimetallic CuII/NiII-SnIV cocrystals

The Schiff base H₂L¹ [N,N'-ethylenebis(3-methoxysalicylaldimine)] or H₂L² [N,N'-ethylenebis(3-ethoxysalicylaldimine)] was reacted with MCl₂·xH₂O and SnCl₄·5H₂O to afford the supramolecular heterobimetallic systems (H₂ED)²⁺·2[ML]·[SnCl₆]^2- [M = Cu, L = L¹ (1), L = L² (2); M = Ni, L = L¹ (3), L = L² (4); ED = 1,2-ethylenediamine], whose structures were established by single crystal X-ray analyses. Each structure includes different entities, viz. a mononuclear [CuL]/[NiL] neutral complex (coformer), a hexachlorostannate dianion [SnCl₆]^2-, a 1,2-ethylenediammonium dication (H₂ED²⁺) and, only in 2 and 4, a methanol molecule. Based on the work of Grothe et al. (Cryst. Growth Des., 2016, 16, 3237-3243), compounds 1 and 3 are cocrystal salts, 2 and 4 are cocrystal salt solvates. The ionic pairs (H₂ED)²⁺·[SnCl₆]^2- in 1-4 are encapsulated by the Cu- or Ni-complexes, and stabilized by N-HO and one N-HCl bond interactions leading to infinite 1D chains. The antimicrobial studies of 1-4 against yeasts (C. albicans and S. cerevisiae) and Gram-positive (S. aureus and E. faecalis) and -negative bacteria (P. aeruginosa and E. coli) indicate that the Ni₂Sn systems (3 and 4) are more active than the analogous Cu₂Sn ones (1 and 2).