Heteroleptic, polynuclear dysprosium(III_{III})-carbamato complexes throughin situcarbon dioxide capture

Amine groups are among the most effective systems for carbon dioxide capture. Reminiscent of the activation of nature\u27s most abundant enzyme RuBisCO, the treatment of amines with CO$_{2}$ in the presence of oxophilic metal ions, e.g. Mg$^{2+}$, 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 CO$_{2}$ with N,N-diisopropylamine and DyCl$_{3}$(DME)$_{2}$ (DME = Dimethoxyethane) in toluene leads to the formation of the tetrametallic complex [Dy$_{4}$(O$_{2}$CNiPr$_{2}$)$_{10}$(O-C$_{2}$H$_{4}$–OMe)$_{2}$]. The addition of 2-hydroxy-3-methoxybenzaldehyde-N-methylimine yields the hexametallic compound [Dy$_{6}$(O$_{2}$CNiPr$_{2}$)$_{8}$(O-C$_{2}$H$_{4}$–OMe)$_{2}$(CO$_{3}$)$_{2}$(C$_{9}$O$_{2}$NH$_{10}$)$_{4}$] 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 CO$_{2}$ as a feedstock, we are able to capture up to 2.5 molecules of CO$_{2}$ 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

Room‐Temperature Oxidation of Thulium‐Metal Nanoparticles to the Thulium Oxocluster [Tm5_5O(Oi^iPr)13_{13}]

Zerovalent thulium nanoparticles (2.2±0.3 nm in size) are used as the starting material to prepare single crystals of the thulium oxocluster [Tm$_5$O(O$^i$Pr)$_{13}$]. The reaction is performed by controlled oxidation of the Tm(0) nanoparticles at room temperature (25°C) in isopropanol. The pentanuclear oxocluster contains a non-charged molecular unit with a central Tm$_5$O core and five μ$_1$-, four μ$_2$-, and four μ$_3$-bridging (O$^i$Pr)$^−$ ligands. Single-crystal structure analysis (P2$_1$/n, a=1247.7(6), b=2146.2(15), c=2056.6(9) pm, $\beta$=93.23(1)°) and infrared spectroscopy confirm the oxidation of HO$^i$Pr with formation of H$_2$ and (O$^i$Pr)$^−$. Temperature-dependent measurements show antiferromagnetic coupling. Such a polynuclear [Ln$_5$O(O$^i$Pr)$_{13}$] oxocluster (Ln: lanthanide) is prepared with thulium-metal nanoparticles as a starting material for the first time and points to the suitability of reactive rare-earth metal nanoparticles as starting materials

A Tetranuclear Dysprosium Schiff Base Complex Showing Slow Relaxation of Magnetization

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

Field-Induced Single Molecule Magnetic Behavior of Mononuclear Cobalt(II) Schiff Base Complex Derived from 5-Bromo Vanillin

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

Triangulo -{ErIII^{III}$_{3}} complex showing field supported slow magnetic relaxation

The triangulo-{Er$_{3}$} complex [Er$_{3}$Cl(o-van)$_{3}$(OH)$_{2}$(H$_{2}$O)$_{5}$]Cl$_{3}$·nH$_{2}$O (n = 9.4; H(o-van) = o-vanillin) (1) was generated by an in situ method. The isolated Er(III) complex 1 was characterized by elemental analysis and molecular spectroscopy. The results of single crystal X-ray diffraction studies have shown that 1 is built up of trinuclear [Er$_{3}$Cl(o-van)$_{3}$(OH)$_{2}$(H$_{2}$O)$_{5}$]$^{3+}$ complex cations, chloride anions and water solvate molecules. Within the complex cation the three Er(III) central atoms are placed at the apexes of a triangle which are bridged by three (o-van)$^{–}$ ligands with additional chelating functions and two μ$_{3}$-OH$^{–}$ ligands. Additionally five aqua and one chlorido ligands complete the octa-coordination of the three Er(III) atoms. AC susceptibility measurements reveal that the compound exhibits slow magnetic relaxation with two relaxation modes

Investigations on the Spin States of Two Mononuclear Iron(II) Complexes Based on N-Donor Tridentate Schiff Base Ligands Derived from Pyridine-2,6-Dicarboxaldehyde

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

It\u27s not just the size that matters: crystal engineering of lanthanide-based coordination polymers

Synthesis and characterization of Lewis base free coordination polymers of selected lanthanides are presented. For this purpose, the substituted Cot$^{TIPS}$ ligand (Cot$^{TIPS}$ = 1,4-bis-triisopropylsilyl-cyclo-octatetraendiide) was used to synthesize homoleptic, anionic multidecker compounds of the type [K{Ln$^{III}$(ɳ$^8$-Cot$^{TIPS}$)$_2$}]$_n$. Depending on the solvent used for crystallization and the ionic radii of the lanthanide cations, three different categories of one-dimensional heterobimetallic coordination polymers were obtained in the solid state. For the early lanthanides La and Ce a unique helical conformation was obtained by crystallization from toluene, while the ionic radius of Pr seems to be a turning point towards the crystallization of zigzag polymers. For Er a third structural motif, a trapezoidal wave polymer was observed. Additionally, the zigzag polymer for all compounds could be obtained by changing the solvent from toluene to Et$_2$O, reavealing a correlation between solid-state structure and ionic radii as well as solvent. While photoluminescence (PL) properties of Cot-lanthanide compounds are scarce, the La complexes show ligand centered green luminescence, whereas the Ce complexes reveal deep red emission origin from d–f transitions. The Er-compounds are single-molecule magnets, in which the magnetic relaxation of each Er ion occurs isolated from its neighbors at temperatures above 10 K, while below 9 K a strong antiferromagnetic coupling between the Er ions was seen