Synthesis of new Mn19 analogues and their structural, electrochemical and catalytic properties

We report the synthesis and structural characterisation of new Mn19 and Mn18M analogues, [MnIII12MnII7(μ4-O)8(μ3-OCH3)2(μ3-Br)6(HLMe)12(MeOH)6]Br2 (2) and [MnIII12MnII6Sr(μ4-O8(μ3-Cl)8(HLMe)12(MeCN)6]Cl2 cluster (3), where H3LMe is 2,6-bis(hydroxymethyl)-p-cresol. The electrochemistry of 2 and 3 has been investigated and their activity as catalysts in the oxidation of benzyl alcohol has been evaluated. Selective oxidation of benzyl alcohol to benzaldehyde by O2 was achieved using 1 mol% of catalyst with conversions of 74% (2) and 60% (3) at 140 °C using TEMPO as a co-catalyst. No partial conversion of benzaldehyde to benzoic acid was observed. The results obtained revealed that different operative parameters - such as catalyst loading, temperature, time, solvent and the presence of molecular oxygen - played an important role in the selective oxidation of benzyl alcohol.

Three series of heterometallic NiII–LnIII Schiff base complexes: synthesis, crystal structures and magnetic characterization

Three series of Ni^II–Ln^III complexes were synthesized using compartmental Schiff base ligands in conjunction with auxiliary ligands. Their magnetic properties have been well studied.

Syntheses, structures, and chiroptical and magnetic properties of chiral clusters built from Schiff bases: a novel [MnIIMnIII6NaI2] core

Enantiomeric pairs of clusters with Mn^IIMnIII3Na^I and the unprecedented Mn^IIMnIII6NaI2 cores have been synthesized employing enantiomerically pure Schiff bases.

Manganese clusters of aromatic oximes: synthesis, structure and magnetic properties

With the aim of tuning the structures by using oxime ligands with different non-coordinating groups, three aromatic oxime ligands were designed by fusing oxime groups ([double bond, length as m-dash]N-OH) onto different non-coordinating groups. Their reactions with the corresponding Mn(ii) salts gave five manganese clusters [Mn(μ₃-O)(L¹)₃(DMF)(H₂O)₃Cl]·2DMF·CH₃OH (1), [Mn(μ₃-O)(L²)₃(OAc)(CH₃OH)₂] (2), [Mn(μ₃-O)₂(L²)₆(H₂O)(py)₇](ClO₄)₂·py·0.5CH₃OH·2H₂O (3), [MnO₄(L²)₈(DMF)₄]·DMF·6CH₃CN (4), and [MnMnO₄(L³)₁₂]·3DMF·6H₂O (5), in which H₂L¹, H₂L² and HL³ represent indane-1,2,3-trione-1,2-dioxime, acenaphthenequinone dioxime, and 9,10-phenanthrenedione-9-oxime, respectively. Their structures were determined and studied in detail. 1 and 2 show planar triangular trinuclear Mn structures. 3 has a hexanuclear Mn skeleton formed from two Mn triangular units through inter-trinuclear mutual coordination. 4 and 5 present octanuclear skeletons constructed from planar triangular Mn₃O and tetrahedral Mn₄O secondary building units, respectively, with different symmetries and different oxidation states of the manganese ions. Their structural studies reveal a significant contribution of the parent rings for fusing oxime groups, different non-coordinating groups and anions to the formation of different cluster skeletons. Their magnetic properties were investigated and simulated, which revealed the presence of dominant antiferromagnetic interactions between the metal ions in these compounds.

Heteronuclear Ni(ii)–Ln(iii) (Ln = La, Pr, Tb, Dy) complexes: synthesis and single-molecule magnet behaviour

The crystal structures are reported for three heterometallic Ni₂Ln and a Ni₂Dy₂ complex, using the Schiff base ligand 2-methoxy-6-[(E)-phenyliminomethyl] phenol. Detailed dc and ac magnetic susceptibility studies were reported for all the complexes. The complexes 3 and 4 shows frequency dependent out-of-phase susceptibility signals.

A self-assembled octanuclear complex bearing the uncommon close-packed {Fe4Mn4(μ4-O)4(μ-O)4} molecular core

An Fe/Mn Schiff base complex with an unprecedented metal core type for a heterometallic compound, has been prepared by the one-pot direct synthesis method and magnetostructurally characterized.

Probing the magnetic and magnetothermal properties of M(ii)–Ln(iii) complexes (where M(ii) = Ni or Zn; Ln(iii) = La or Pr or Gd)

We report the crystal structures of Ni(ii)–Ln(iii) (where Ln = Gd or Pr) complexes and their suitably substituted diamagnetic analogues. Magnetic characterization revealed the nature of the magnetic exchange interactions and the magnetothermal properties.