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Synthesis of new organo-lanthanide polyphosphides with an aromatic cyclo-[P4]2− moiety and a cyclo-[P3]3− moiety is presented.

A dinuclear dysprosium(iii) complex [Dy2(NO3)3(L)3]·nCH3OH (n = 1.20; HL = (2-[(2-hydroxy-propylimino)methyl]phenol)) (1) was isolated when dysprosium nitrate reacted with a solution of salicylaldehyde and 1-amino-2-propanol in a basic medium under in-situ reaction conditions.

The triangulo-{Er3} complex [Er3Cl(o-van)3(OH)2(H2O)5]Cl3·nH2O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method.

Herein, we present the synthesis and characterization of heteroleptic lanthanide complexes bearing a dianionic ��5-plumbole ligand in their coordination sphere. The reaction proceeds via a salt elimination reaction between the dilithioplumbole ([Li(thf)]$_2$[1,4-bis-tert-butyl-dimethylsilyl-2,3-bis-phenyl-plumbolyl] = [Li$_2$(thf)$_2$(��$^5$-L$^Pb$)]) and specifically designed [Ln(��$^8$-COT$^TIPS$)BH$_4$] precursors (Ln = lanthanide, La, Ce, Sm, Er; COT$^TIPS$ = 1,4-bis-triisopropylsilyl-cyclooctatetraenyl), that are capable of stabilizing a planar plumbole moiety in the coordination sphere of different trivalent lanthanide ions. In-depth ab initio calculations show that the aromaticity of the dianionic plumbole is retained upon coordination. Electron delocalization occurs from the plumbole HOMO to an orbital of mainly d-character at the lanthanide ion. The magnetic properties of the erbium congener were investigated in detail, leading to the observation of magnetic hysteresis up to 5 K (200 Oe s$^���1$), an unequivocal proof for single molecule magnet behavior in this system. The magnetic behavior of the erbium species can be modulated by manipulating the position of the lithium cation in the complex, which directly influences the bonding metrics in the central [(��$^5$-L$^Pb$)Er(��$^8$-COT$^TIPS$)]��� fragment. This allowed us to assess a fundamental magneto-structural correlation in an otherwise identical inner coordination sphere.

A mononuclear Co(II) complex of a Schiff base ligand derived from 5-Bromo-vanillin and 4-aminoantipyrine, that has a compressed tetragonal bipyramidal geometry and exhibiting field-induced slow magnetic relaxation, has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis and molecular spectroscopy. In the crystal packing, a hydrogen-bonded dimer structural topology has been observed with two distinct metal centers having slightly different bond parameters. The complex has been further investigated for its magnetic nature on a SQUID magnetometer. The DC magnetic data confirm that the complex behaves as a typical S = 3/2 spin system with a sizable axial zero-field splitting parameter D/hc = 38 cm−1. The AC susceptibility data reveal that the relaxation time for the single-mode relaxation process is τ = 0.16(1) ms at T = 2.0 K and BDC = 0.12 T.

Amine groups are among the most effective systems for carbon dioxide capture. Reminiscent of the activation of nature's most abundant enzyme RuBisCO, the treatment of amines with CO2 in the presence of oxophilic metal ions, e.g. Mg2+, results in the formation of carbamates. Here we report the synthesis, structure and magnetic properties of three new dysprosium-carbamato complexes. The reaction of gaseous CO2 with N,N-diisopropylamine and DyCl3(DME)2 (DME = Dimethoxyethane) in toluene leads to the formation of the tetrametallic complex [Dy4(O2CNiPr2)10(O-C2H4–OMe)2]. The addition of 2-hydroxy-3-methoxybenzaldehyde-N-methylimine yields the hexametallic compound [Dy6(O2CNiPr2)8(O-C2H4–OMe)2(CO3)2(C9O2NH10)4] in which the metal sites form a chair-like configuration; The same hexanuclear motif is obtained using N,N-dibenzylamine. We show that by employing CO2 as a feedstock, we are able to capture up to 2.5 molecules of CO2 per Dy ion. Magnetic measurements show a decreasing χMT at low temperatures. Combining the experimental magnetic data with ab initio calculations reveils tilting of the easy axes and implies the presence of antiferromagnetic interactions between the Dy(III) metal ions.

A tetranuclear dysprosium Schiff base complex was isolated by reacting dysprosium chloride with 2-hydroxy-3-methoxybenzaldehyde and 2-(aminomethyl)pyridine in-situ under basic conditions. The isolated Dy(III) complex was characterized by elemental analyses, single crystal X-ray diffraction and molecular spectroscopy. The complex crystallizes in the triclinic space group P-1 with unit cell parameters of a = 10.2003 (4), b = 13.8602 (5), c = 14.9542 (6), α = 94.523 (3), β = 109.362 (4), and γ = 99.861 (3). The magnetic properties of 1 have been investigated by DC and AC susceptibility measurements. The DC measurements reveal weak exchange coupling of antiferromagnetic nature. In the AC measurement, the complex shows a slow relaxation of magnetization in the absence of an external magnetic field.

We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6‐bis((E)‐1‐(2‐(pyridin‐2‐yl)‐hydrazineylidene)ethyl)pyridine (H2dapp) [Dy(H2dapp)(NO3)2]NO3 (1), [Dy(H2dapp)(OAc)2]Cl (2) and [Dy(H2dapp)(NO3)2]Cl0.92(NO3)0.08 (3). The (H2dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N−H group of the (H2dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds1 and 2 is the presence of short nitrate‐nitrate intermolecular ligand contact opening further lattice relaxation pathways., Three new dysprosium complexes with a pentadentate ligand occupying five equatorial sites differ only in the nature of the axial ligands. These help tune the relaxation properties as judged by an analysis of the AC susceptibility data. More in depth analysis by using two recently suggested fitting equations lead to similar outcomes for all three systems. As a further contribution to the relaxation pathway involving the phonon bath it is concluded that a short nitrate‐nitrate interaction between molecules helps dampen the spin phonon coupling.

Iron(II)-Schiff base complexes are a well-studied class of spin-crossover (SCO) active species due to their ability to interconvert between a paramagnetic high spin-state (HS, S = 2, $^{5}$T$_{2}$) and a diamagnetic low spin-state (LS, S = 0, $^{1}$A$_{1}$) by external stimuli under an appropriate ligand field. We have synthesized two mononuclear FeII complexes, viz., [Fe(L$^{1}$)$_{2}$](ClO$_{4}$)$_{2}$.CH$_{3}$OH (1) and [Fe(L$^{2}$)$_{2}$](ClO$_{4}$)$_{2}$.2CH$_{3}$CN (2), from two N$_{6}$–coordinating tridentate Schiff bases derived from 2,6-bis[(benzylimino)methyl]pyridine. The complexes have been characterized by elemental analysis, electrospray ionization–mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FTIR), solution state nuclear magnetic resonance spectroscopy, $^{1}$H and $_{13}$C NMR (both theoretically and experimentally), single-crystal diffraction and magnetic susceptibility studies. The structural, spectroscopic and magnetic investigations revealed that 1 and 2 are with Fe–N$_{6}$ distorted octahedral coordination geometry and remain locked in LS state throughout the measured temperature range from 5–350 K.

We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6-bis((E)-1-(2-(pyridin-2-yl)-hydrazineylidene)ethyl)pyridine (H2dapp) [Dy(H2dapp)(NO3)2]NO3 (1), [Dy(H2dapp)(OAc)2]Cl (2) and [Dy(H2dapp)(NO3)2]Cl0.92(NO3)0.08 (3). The (H2dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N−H group of the (H2dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds1 and 2 is the presence of short nitrate-nitrate intermolecular ligand contact opening further lattice relaxation pathways.