Oxidative Dissolution of Lanthanide Metals Ce and Ho in Molten GaCl3.

Gallium trichloride (GaCl3) was used as a solvent for the oxidative dissolution of the lanthanide (Ln) metals cerium (Ce) and holmium (Ho). Reactions were performed at temperatures above 100 °C in sealed vessels to maintain the liquid phase for GaCl3 during the oxidizing reactions. The best results were obtained from reactions using 8 equiv of GaCl3 to metal where the inorganic complexes [Ga][Ln(GaCl4)4] [Ln = Ce (1), Ho (2)] could be isolated. Recrystallization of 1 and 2 employing fluorobenzene (C6H5F) produced [Ga(η6-C6H5F)2][Ln(GaCl4)4] [Ln = Ce (3), Ho (4)] where reversible η6 coordination of C6H5F to [Ga]+ was observed. All complexes were characterized through elemental analysis (F and Cl), IR and UV-vis-near-IR spectroscopies, and both solution and solid-state NMR techniques.

Synthesis and Magnetic Properties of Antimony-Ligated Co(II) Complexes: Stibines versus Phosphines.

Herein, we test the hypothesis that neutral, heavy-atom stibine donors can increase the extent of spin-orbit coupling on light, 3d transition metal. To this end, we developed a novel synthetic route toward coordinating a paramagnetic 3d metal ion─cobalt(II)─with neutral stibine ligands. Such complexes have not been reported in the literature due to the weak σ donor strength of stibines and the hard-soft mismatch between a 3d metal and a 5p ligand─which herein has been overcome using alkylated Sb donors. Magnetometry of [(SbiPr2Ph)2Co(I)2] (1) reveals that the stibine complex 1 exhibits a higher magnitude D value (D = |24.96| cm-1) than the spectroscopically derived value for the corresponding phosphine complex 3 (D = -13.13 cm-1), indicative of large zero-field splitting. CASSCF/NEVPT2 calculations corroborate the experimental D values for 1 and 3, predicting D = -31.9 and -8.9 cm-1, respectively. A re-examination of magnetic parameters across the entire series [(ER3)2Co(X)2] (E = P → Sb; X = Cl → I) reveals that (i) increasingly heavy pnictogens lead to an increased X-Co-X bond angle, which is correlated with larger magnitude D values, and (ii) for a given X-Co-X bond angle, the D value is always higher in the presence of a heavy pnictogen as compared with a heavy halide. Ab initio ligand field theory calculations for 1 (stibine complex) and 3 (phosphine complex) reveal no substantial differences in spin-orbit coupling (ζ = 479.2, 480.2 cm-1) or Racah parameter (B = 947.5, 943.9 cm-1), an indicator of covalency. Thus, some "heavy atom effect" on the D value beyond geometric perturbation is operative, but its precise mechanism(s) of action remains obscure.

Isolation and X-ray Structure of a Dialkylbismuth(III) Iodo "Nanosquare": Breaking the Polymeric Mold of R2BiX.

We report the synthesis, X-ray structure, and solution behavior of a "nanosquare" formed by four repeating (iPr2BiI) units. The title complex [iPr2BiI]4 (1) formed spontaneously as the major product from the reaction of iPr3Bi with MI2 (M = Mn, Co, Fe). Complex 1 was then more directly synthesized via bromination of iPr3Bi to form (iPr2BiBr), followed by iodide substitution. The X-ray structure of 1 exhibited acute Bi-I-Bi bonds (∼85-95°) that enabled formation of the hollow square motif. Synthetic control experiments with R2BiX (R = iPr, Bn; X = I, Br) revealed that the identities of both the halide and bismuth R group are determinants for square formation: the bromo-substituted [iPr2BiBr]n (2) and benzyl-substituted [Bn2BiI]n (3) variants formed only polymers as determined by X-ray crystallography. Density functional theory calculations revealed nearly pure p-orbital-based bonding molecular orbitals on both iodide and bismuth, facilitating the ∼90°/180° bonding motifs.