Origins of stereoselectivity in ROP of racemic chiral cyclic esters promoted by achiral yttrium complexes, resulting in the formation of highly heterotactic polylactide, and highly syndiotactic or, more uniquely, highly isotactic poly(3-hydroxybutyrate)s, are discussed. A close interplay between the nature of the cyclic ester, most particularly of the exocyclic functional chain installed on the chiral center of β-lactones, and the ortho-substituents installed on the phenolate rings of the ligand, results in various determining secondary interactions of steric and also electronic nature.

Reported herein is the first stereoselective controlled ROP of a specific family of racemic functional β-lactones, namely 4-alkoxymethylene-β-propiolactones (BPL s). This process is catalyzed by an yttrium complex stabilized by a nonchiral tetradentate amino alkoxy bisphenolate ligand {ONOO } , which features both a good activity and a high degree of control over the molar masses of the resulting functional poly(3-hydroxyalkanoate)s. A simple modification of the R' substituents in ortho and para position on the ligand platform allows for a complete reversal from virtually pure syndioselectivity (P up to 0.91 with R'=cumyl) to very high isoselectivity (P up to 0.93 with R'=Cl), as supported by DFT insights. This is the first example of a highly isoselective ROP of a racemic chiral β-lactone.

A neutral air-and moisture-stable N,N′chelating radical ligand, 1-phenyl-3-(pyrid-2-yl)benzo[e]-[1,2,4]triazinyl (1) was synthesized and characterized by electron paramagnetic resonance spectroscopy, X-ray crystallography, and magnetic measurements. Subsequent reaction of 1 with Cu(hfac) 2 •2H 2 O (hfac = hexafluoroacetylacetonate) under ambient conditions afforded the coordination complex Cu(1)(hfac) 2 in which the radical binds to the metal in a bidentate fashion. Magnetic susceptibility data collected from 1.8 to 300 K indicate a strong ferromagnetic metal-radical interaction in the complex and weak antiferromagnetic radical•••radical interactions between the Cu(1)(hfac) 2 units. Detailed computational investigations support this assignment. Radical 1 is a new addition to the growing library of 1,2,4-triazinyl radicals and the first member of this family of paramagnetic species synthesized specifically for coordination purposes.

The anion [3,3'-Co(C2B9H11)2](-) ([COSAN](-)) produces aggregates in water. These aggregates are interpreted to be the result of C-H⋅⋅⋅H-B interactions. It is possible to generate aggregates even after the incorporation of additional functional groups into the [COSAN](-) units. The approach is to join two [COSAN](-) anions by a linker that can adapt itself to act as a crown ether. The linker has been chosen to have six oxygen atoms, which is the ideal number for K(+) selectivity in crown ethers. The linker binds the alkaline metal ions with different affinities; thus showing a distinct degree of selectivity. The highest affinity is shown towards K(+) from a mixture containing Li(+), Na(+), K(+), Rb(+) and Cs(+); this can be indicative of pseudo-crown ether performance of the dumbbell. One interesting possibility is that the [COSAN](-) anions at the two ends of the linker can act as a hook-and-loop fastener to close the ring. This facet is intriguing and deserves further consideration for possible applications. The distinct affinity towards alkaline metal ions is corroborated by solubility studies and isothermal calorimetry thermograms. Furthermore, cryoTEM micrographs, along with light scattering results, reveal the existence of small self-assemblies and compact nanostructures ranging from spheres to single-/multi-layer vesicles in aqueous solutions. The studies reported herein show that these dumbbells can have different appearances, either as molecules or aggregates, in water or lipophilic phases; this offers a distinct model as drug carriers.

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Selective laser sintering (SLS) 3D printing is used to fabricate highly macroporous ion scavenger filters for recovery of Pd and Pt from electronic waste. The scavengers are printed by using a mixture of polypropylene with 10 wt% of type‐1 anion exchange resin. Porosities and the flow‐through properties of the filters are controlled by adjusting the SLS printing parameters. The cylinder‐shaped filters are used in selective recovery of Pd and Pt from acidic leachate of electronic waste simply by passing the solution through the object. Under such conditions, the scavenger filters are able to capture Pd and Pt as anionic complexes with high efficiency from a solution containing mixture of different metal ions. By using the Pd/Pt scavenger together with previously reported, highly selective nylon‐based Au scavenger, precious metals, i.e., Au, Pd, and Pt could all be recovered from the electronic waste leachate in a single flow‐through process. One of the main advantages of the printed scavengers is that all recovered metals can be easily extracted from the filters as separate fractions by using aqueous solutions of thiourea or diluted nitric acid. After removal of the captured metals, the scavengers are reusable without significant loss of their ion‐capturing performance.

The experimental and theoretical charge densities in the sulfido-bridged cluster compounds Fe2(μ-S2)(CO)6 (1), Fe3(μ3-S)2(CO)9 (2), Mn2(μ-S2)(μ-CO)(CO)6 (3), and Fe2(μ-S2)(CO)5(PPh3) (4) have been studied using the quantum theory of atoms in molecules (QTAIM) methodology. High-resolution X-ray diffraction data have been measured for compounds 2–4 at 100 K. The topological analyses show that only in compounds 1 and 4 is there any evidence for metal–metal bonding in terms of the presence of a bond path. For compound 1, the topology of the Fe2S2 cage is highly dependent on the Fe–Fe separation, and the deformation along this vector is an extremely soft mode. The experimentally observed topology for compound 4 is the open “butterfly” topology. The orbital decomposition of the delocalization indices associated with the metal–metal interactions, δ(ΩM–ΩM), implies significant direct Fe–Fe bonding in compounds 1 and 4 and for two of the Fe–Fe vectors in 2 but only a very minor Mn–Mn interaction in compound 3. The crystal structure of 2 shows a small amount (∼1%) of orientational disorder. As a result, a small degradation of the derived topological parameters is detectable, in comparison with the ordered structures of 3 and 4, and this leads us to discourage any quantitative QTAIM studies on disordered systems.

A family of MnLn strictly dinuclear complexes of general formula [Mn(μ-L)(μ-OMe)(NO)Ln(NO)(MeOH)] (Ln = Gd, Dy, Er, Ho) has been assembled in a one pot synthesis from a polydentate, multipocket aminobis(phenol)ligand [6,6'-{(2-(1-morpholyl)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol)], Mn(NO)·4HO, Ln(NO)· nHO, and NEt in MeOH. These compounds represent the first examples of fully structurally and magnetically characterized dinuclear MnLn complexes. Single X-ray diffraction studies reveal that all complexes are isostructural, consisting of neutral dinuclear molecules where the Mn and Ln metal ions, which exhibit distorted octahedral MnNO and distorted LnO coordination spheres, are linked by phenoxide/methoxide double bridging groups. Static magnetic studies show that the MnGd derivative exhibits a weak antiferromagnetic interaction between the metal ions, with a negative axial zero-field splitting D parameter. The MnGd complex shows a notable magnetocaloric effect with magnetic entropy change at 5 T and 3 K of -Δ S = 16.8 J kg K. Theoretical studies were performed to support the sign and magnitude of the magnetic anisotropy of the Mn ion ( ab initio), to predict the value and nature of J, to disclose the mechanism of magnetic coupling, and to establish magneto-structural correlations (DFT calculations). The results of these calculations are corroborated by quantum theory of atoms in molecule analysis (QTAIM). Finally, Mn-Dy and Mn-Er complexes show field-induced slow relaxation of the magnetization but without reaching a maximum above 2 K in the out-of-phase ac susceptibility. Ab initio calculations were also performed on Mn-Dy/Ho systems to unravel the origin behind the weak SMM characteristics of the molecules possessing two strongly anisotropic ions. The mechanism of magnetic relaxation was developed, revealing a large QTM/tunnel splitting at the single-ion level. Furthermore, the anisotropy axes of the Mn and Ln ions were calculated to be noncollinear, leading to reduction of the overall anisotropy in the molecules. Hence, the herein reported complexes demonstrate that a combination of two anisotropic metal ions does not guarantee SMM behavior.