Microwave-assisted Synthesis, Structure, and Properties of a Heptanuclear Cobalt Cluster with 2-Ethyliminomethyl-6-methoxy-phenol

Heptanuclear Mixed-Valence Co4IIICo3II Molecular Wheel─A Molecular Analogue of Layered Double Hydroxides with Single-Molecule Magnet Behavior and Electrocatalytic Activity for Hydrogen Evolution Reactions

We present a bifunctional heptanuclear cobalt(II)/cobalt(III) molecular complex formulated as [Co7(μ3-OH)4(H2L1)2(HL2)2](NO3)6·6H2O (1) (where H5L1 is 2,2'-(((1E,1'E)-((2-hydroxy-5-methyl-1,3-phenylene)bis(methanylylidene))bis(azanylylidene))bis(propane-1,3-diol)) and H2L2 is 2-amino-1,3-propanediol). Compound 1 has been characterized by single-crystal X-ray diffraction analysis along with other spectral and magnetic measurements. Structural analysis indicates that 1 contains a mixed-valence Co7 cluster where a central Co(II) ion is connected to six different Co centers (four CoIII and two CoII ions) by four μ3-OH groups, giving rise to a planar heptanuclear cluster that resembles a molecular fragment of a layered double hydroxide (LDH). Two triply deprotonated (H2L1)3- ligands form the outer side of the cluster while two singly deprotonated (HL2)- ligands are located at the top and bottom of the central heptanuclear core. Variable temperature magnetic measurements indicate the presence of weak ferromagnetic CoII···CoII interactions (J = 3.53(6) cm-1) within the linear trinuclear CoII cluster. AC susceptibility measurements show that 1 is a field-induced single-molecule magnet (SMM) with τ0 = 8.2(7) × 10-7 s and Ueff = 11.3(4) K. The electrocatalytic hydrogen evolution reaction (HER) activity of 1 in homogeneous phase shows an overpotential of 455 mV, with a Faradaic efficiency of 81% and a TOF of 8.97 × 104 μmol H2 h-1 mol-1.

Cobalt complexes of the chelating dicarboxylate ligand "esp": a paddlewheel-type dimer and a heptanuclear coordination cluster

The coordination chemistry of Co(ii) with the chelating dicarboxylate ligand esp (esp = α,α,α',α'-tetramethyl-1,3-benzenedipropionate) is explored. We report here the bimetallic paddlewheel-type dimer, Co2(esp)2(EtOH)2 (1), and a bowl-shaped, heptanuclear coordination cluster, Co7(OH)4(Hesp)2(esp)4(MeCN)2·4MeCN (2). Crystal structures of both complexes are reported as well as their magnetic properties, which indicate antiferromagnetic interactions among the Co(ii) ions.

New molecular heptanuclear cobalt phosphonates: synthesis, structures and magnetic properties

Synthesis, structures and magnetic properties (strong anisotropy, ferromagnetic and antiferromagnetic interactions) of novel {Co₇} homoleptic molecular cobalt phosphonates with a similar structure motif are described.

Crystal structure of catena-poly[hexakis(μ2-2-acetylphenolato-κ3 O:O,O′)trimanganese(II)], C48H42Mn3O12

C48H42Mn3O12, triclinic, P1̅ (no. 2), a = 9.1889(6) Å, b = 9.3226(9) Å, c = 12.8605(11) Å, α = 79.231(8)°, β = 73.223(7)°, γ = 89.228(7)°, V = 1035.26(15) Å3, Z = 1, R gt(F) = 0.0593, wR ref(F 2) = 0.1664, T = 293 K.

Competitive coordination aggregation for V-shaped [Co3] and disc-like [Co7] complexes: synthesis, magnetic properties and catechol oxidase activity

The synthetic procedures, magnetic properties and catecholase-like activity of a V-shaped [CoII3L₄] and planar disc-like [CoII7L₆] complexes have been discussed.

Microwave-assisted synthesis, structure and property of a spin-glass heptanuclear nickel cluster with 2-iminomethyl-6-methoxy-phenol

A new heptanuclear nickel cluster [Ni7(immp)6(OMe)6]·(ClO4)2 (1, Himmp is 2-iminomethyl-6-methoxy-phenol) has been synthesized through the microwave-assisted reaction of Ni(ClO4)2·6H2O with 2-hydroxy-3-methoxy-benzaldehyde and ammonium water in mixed solvent (acetonitrile: methanol = 1:1). Complex 1 was characterized by IR spectroscopy, elemental analysis and X-ray single-crystal diffraction. Magnetic property of 1 indicates the relaxation time τ 0 = 1.28 × 10–15 s and the energy barrier U eff / k B = 70.4 K, which is a spin glass.

Structural variation from heterometallic heptanuclear or heptanuclear to cubane clusters based on 2-hydroxy-3-ethoxy-benzaldehyde: effects of pH and temperature

Five novel clusters were reported, with results showing that pH and reaction temperatures have a key role in the self-assembly process.