Solid-State NMR Study of Paramagnetic Bis(alaninato‑κ²<i>N</i>,<i>O</i>)copper(II) and Bis(1-amino(cyclo)alkane-1-carboxylato‑κ²<i>N</i>,<i>O</i>)copper(II) Complexes: Reflection of Stereoisomerism and Molecular Mobility in ¹³C and ²H Fast Magic Angle Spinning Spectra

Solid-state stereochemistry and mobility of paramagnetic copper­(II) complexes formed by aliphatic amino acids (l-alanine, d,l-alanine, 1-amino-2-methyl-alanine) and 1-amino­(cyclo)­alkane-1-carboxylic acids (alkane = propane, butane, pentane, hexane) as bidentate ligands has been studied by ¹³C and ²H solid-state fast magic angle spinning (MAS) NMR spectroscopy. We examined the prospective method to characterize solid-state paramagnetic compounds in a routine way. Both ¹³C and ²H MAS spectra can distinguish d,l and l,l diastereomers of natural and polydeuterated bis­([D_<i>n</i>]­alaninato)­copper­(II) (<i>n</i> = 0, 2, 8) complexes with axial and/or equatorial methyl positions (conformations) primarily due to different Fermi-contact (FC) contributions. The three-bond hyperfine couplings clearly show Karplus-like dependence on the torsional angles which turned out to be a useful assignment aid. Density functional theory calculations of the FC term and crystal structures were also used to aid the final assignments. The correlations obtained for bis­(alaninato-κ²<i>N</i>,<i>O</i>)­copper­(II) complexes were successfully used to characterize other complexes. The usefulness of the ²H MAS spectra of the deuterated complexes was underlined. Even the spectra of the easily exchangeable amine protons contained essential stereochemical information. In the case of a dimer structure of bis­(1-aminohexane-1-carboxylato-κ²<i>N</i>,<i>O</i>)­copper­(II) both the ¹³C and ²H resolutions were good enough to confirm the presence of the <i>cis</i> and <i>trans</i> forms in the asymmetric unit. With regard to the internal solid-state motions in the crystal lattice, the obtained quadrupolar tensor parameters were similar for the d,l- and l,l-alaninato isomers and also for the <i>cis–trans</i> forms suggesting similar crystal packing effects, static amine deuterons involved in hydrogen bonding, and fast rotating methyl groups

Dithallium(III)-Containing 30-Tungsto-4-phosphate, [Tl₂Na₂(H₂O)₂(P₂W₁₅O₅₆)₂]^16–: Synthesis, Structural Characterization, and Biological Studies

Here we report on the synthesis and structural characterization of the dithallium­(III)-containing 30-tungsto<i>-</i>4-phosphate [Tl₂Na₂(H₂O)₂­{P₂W₁₅O₅₆}₂]^16– (<b>1</b>) by a multitude of solid-state and solution techniques. Polyanion <b>1</b> comprises two octahedrally coordinated Tl³⁺ ions sandwiched between two trilacunary {P₂W₁₅} Wells–Dawson fragments and represents only the second structurally characterized, discrete thallium-containing polyoxometalate to date. The two outer positions of the central rhombus are occupied by sodium ions. The title polyanion is solution-stable as shown by ³¹P and ^203/205Tl NMR. This was also supported by Tl NMR spectra simulations including several spin systems of isotopologues with half-spin nuclei (²⁰³Tl, ²⁰⁵Tl, ³¹P, ¹⁸³W). ²³Na NMR showed a time-averaged signal of the Na⁺ counter cations and the structurally bonded Na⁺ ions. ^203/205Tl NMR spectra also showed a minor signal tentatively attributed to the trithallium-containing derivative [Tl₃Na­(H₂O)₂­(P₂W₁₅O₅₆)₂]^14–, which could also be identified in the solid state by single-crystal X-ray diffraction. The bioactivity of polyanion <b>1</b> was also tested against bacteria and <i>Leishmania</i>