Structure and Magnetic Properties of Homoleptic Trivalent Tris(alkyl)lanthanides.

Six new solvent-free, homoleptic paramagnetic tris(alkyl)lanthanides Ln{C(SiHMe)} () and Ln{C(SiHMe)Ph} () (Ln = Gd, Dy, and Er) were synthesized to investigate the magnetic properties of 4f organometallic compounds stabilized by secondary Ln↼H-Si and benzylic interactions. The unit cell of contains one independent molecule ( = 2), while and crystallize with four independent isostructural molecules per unit cell ( = 16). In all molecules, as in other compounds, the three tris(dimethylsilyl)methyl ligands form a trigonal planar LnC core, and six secondary interactions involving Ln↼H-Si bonding in Ln{C(SiHMe)} form above and below the equatorial plane.

Rationally designed rare earth separation by selective oxalate solubilization.

A simple, environmentally benign, and efficient chemical separation of rare earth oxalates (CSEREOX) within two rare earth element (REE) subgroups has been developed. The protocol allows for selective solubilization of water-insoluble oxalates of rare earth elements, and results in efficient REE extraction even at low initial concentrations (<5%) from processed magnet wastes.

Computational Study of the Malonic Acid Tautomerization Products in Highly Concentrated Particles.

Knowing the tautomeric form of malonic acid (MA) in concentrated particles is critical to understanding its effect on the atmosphere. Energies and vibrational modes of hydrated MA particles were calculated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level and the effective fragment potential (EFP) method. Visualization of the keto and enol isomer vibrational modes enabled the assignment of keto isomer peaks in the 1710-1750 cm range, and previously unidentified experimental IR peaks in the 1690-1710 cm can now be attributed to the enol isomer.

ParFit: A Python-Based Object-Oriented Program for Fitting Molecular Mechanics Parameters to ab Initio Data.

A newly created object-oriented program for automating the process of fitting molecular-mechanics parameters to ab initio data, termed ParFit, is presented. ParFit uses a hybrid of deterministic and stochastic genetic algorithms. ParFit can simultaneously handle several molecular-mechanics parameters in multiple molecules and can also apply symmetric and antisymmetric constraints on the optimized parameters.

Structure and interactions of plant cell-wall polysaccharides by two- and three-dimensional magic-angle-spinning solid-state NMR.

The polysaccharide-rich cell walls (CWs) of plants perform essential functions such as maintaining tensile strength and allowing plant growth. Using two- and three-dimensional magic-angle-spinning (MAS) solid-state NMR and uniformly (13)C-labeled Arabidopsis thaliana, we have assigned the resonances of the major polysaccharides in the intact and insoluble primary CW and determined the intermolecular contacts and dynamics of cellulose, hemicelluloses, and pectins. Cellulose microfibrils showed extensive interactions with pectins, while the main hemicellulose, xyloglucan, exhibited few cellulose cross-peaks, suggesting limited entrapment in the microfibrils rather than extensive surface coating.