SOLID-STATE NMR-STUDIES OF MAGNETO STRUCTURAL CORRELATIONS IN ANHYDROUS COPPER(II) CARBOXYLATES

Magneto-structural correlations are probed in a series of anhydrous copper(II) carboxylates via solid-state NMR spectroscopic techniques. Temperature-dependent C-13 cross-polarization magic-angle-spinning (CP/MAS) results are presented for copper(II) propionate (Cu2(C2H5CO2)4), copper(II) isobutyrate (Cu2(C3H7CO2)4), and copper(II) isovalerate (Cu2(C4H9CO2)4). Observed contact shifts are related to magnetic information and used to calculate singlet-triplet energy level separations (-2J), diamagnetic chemical shifts (delta-dia), and electron-nucleus hyperfine coupling constants (A). As structural information is manifest in NMR signal multiplicity, this report also includes an X-ray crystal structure determination of Cu2(C4H9CO2)4. The compound crystallized in the triclinic space group P1BAR (No. 2), with a = 5.1910 (13) angstrom, b = 10.840 (2) angstrom, c = 11.063 (2) angstrom, alpha = 83.120 (15)-degrees, beta = 86.92 (2)-degrees, gamma = 85.60 (2)-degrees, Z = 1, and V = 615.6 (2) angstrom-3. Full-matrix least-squares refinement on F2 yielded the final R value of 0.0654 for 1571 unique observed reflections.