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A small but growing number of molecular compounds have been isolated featuring divalent lanthanides with 4f

The recent discovery of metal-metal bonding and valence delocalization in the dilanthanide complexes (CpiPr5)2Ln2I3 (CpiPr5 = pentaisopropylcyclopentadienyl; Ln = Y, Gd, Tb, Dy) opened up the prospect of harnessing the 4fn5dz21 electron configurations of non-traditional divalent lanthanide ions to access molecules with novel bonding motifs and magnetism. Here, we report the trinuclear mixed-valence clusters (CpiPr5)3Ln3H3I2 (1-Ln, Ln = Y, Gd), which were synthesized via potassium graphite reduction of the trivalent clusters (CpiPr5)3Ln3H3I3. Structural, computational, and spectroscopic analyses support valence delocalization in 1-Ln resulting from a three-center, one-electron σ bond formed from the 4dz2 and 5dz2 orbitals on Y and Gd, respectively. Dc magnetic susceptibility data obtained for 1-Gd reveal that valence delocalization engenders strong parallel alignment of the σ-bonding electron and the 4f electrons of each gadolinium center to afford a high-spin ground state of S = 11. Notably, this represents the first clear instance of metal-metal bonding in a molecular trilanthanide complex, and the large spin-spin exchange constant of J = 168(1) cm-1 determined for 1-Gd is only the second largest coupling constant characterized to date for a molecular lanthanide compound.

Reported herein is the utilization of bis[(pinacolato)boryl]methylzinc halides, whose structures are characterized via single-crystal X-ray analysis, as solid storable reagents for copper-catalyzed coupling with vinyliodonum salts. The reaction proceeds under mild conditions and shows broad scope with respect to vinyliodonium salts, affording various α-boryl-substituted allylboronate esters in good yields. Synthetic applications of the obtained products are also demonstrated.

A new dinitrogen (N2) molybdenum(0) complex supported exclusively by pyridine ligands was synthesized. The X-ray crystal structure of the complex elucidated the activated nature of the N2 ligand, consistent with a low N–N IR stretching frequency. Natural bond orbital (NBO) analyses on this system confirmed a strong π-backdonation arising from the large p orbital character in molybdenum lone pairs. The protonation of the N2 ligand using decamethyl chromocene (CrCp*2) in the presence of lutidinium salt afforded 1.22 equivalents of ammonia (NH3).

OBJECTIVE This study was conducted to evaluate the fermentation characteristics under low mesophilic temperature of spent instant coffee ground (SICG) and to estimate the effect of fermented SICG (FSICG) as alternative feed ingredient on milk productivity of dairy cows. METHODS In the fermentation trial, fermentation of SICG was performed to investigate changes in characteristics using the microbial mixture (Lactobacillus plantarum, Saccharomyces cerevisiae, and Bacillus subtilis = 1:1:1) for 21 days at 20°C under anaerobic conditions. Molasses was added at 5% of dry mass. In the animal trial, eighteen Holstein Friesian cows were used to evaluate the nutritive value of the FSICG which was fermented for 14 days under the same condition as the fermentation trial. RESULTS In the fermentation trial, the dry matter (DM) and organic matter content linearly decreased with fermentation time (p

The synthesis of sandwich-shaped multinuclear silver complexes with planar penta- and tetranuclear wheel-shaped silver units and a central anion, [Agn(2-HPB)2(A-)](OTf-)n-1, nAgA, n = 4 or 5 and A- = OH- or F- or Cl-, is reported, along with complete spectroscopic and structural characterization. An NMR mechanistic study reveals that silver complexes were formed in the following order: 2Ag → 3AgH2O → 5AgOH → 4AgOH. The central hydroxides in 4AgOH and 5AgOH exhibit exotic physical properties due to the confined environment inside the complex. The size of these silver wheels can be tuned by changing the central anion or extracting/adding one silver atom. This study provides the facile way to synthesize discrete wheel-shaped multinuclear silver complexes and provides valuable insights into the dynamics of the self-assembly process.

A study of the coordination chemistry of the hexa(2-pyridyl)benzene (2-HPB) ligand with copper(II) ions is presented. The 2-HPB ligand featuring six pyridine moieties can bind to a metal center in a number of different ways. Herein, we discuss dicopper(II) complexes of 2-HPB that vary in coordination geometry. Thus, the four complexes obtained (1, 2, 3, and 4) adopt two different conformations, “(A,B)(C,D)-trans” (in 1 and 4) and “(A,B)(D,E)-trans” (in 2 and 3). The structure of the complex strongly depends on the solvent used (water, ethanol, and dimethylformamide (DMF)). In an aqueous solution, the formation of complexes 1 and 2 can be controlled by the choice of crystallization conditions. All the products were characterized by X-ray diffraction. The coordination preference of 2-HPB is evaluated in the context of hydrogen bonding in the solid state.

By changing the concentration of copper salt (Cu(ClO4)2), a two-dimensional (2D) copper paddle-wheel-based metal–organic framework (MOF) containing an imidazolium unit (Im-MOF-1 with a framework formula of [CuII(L)(NMP)](ClO4), L = 1,3-bis(4-carboxyphenyl)imidazolium and NMP = N-methyl-2-pyrrolidone) and a 3D MOF (Im-MOF-2, CuII(L)(H2O)) with aqua-bridged Cu ions as inorganic infinite secondary building units were respectively prepared. With CuCl as a copper source, another square-grid 2D MOF (Im-MOF-3, CuII(LNHC–CuICl)(NMP), LNHC = a carbene form of L) was obtained; Im-MOF-3 is isostructural with Im-MOF-1 except that its organic linker has an N-heterocyclic carbene (NHC) copper(I) complex (LNHC–CuICl). Density functional theory modeling calculations show that the NHC–CuCl complex in the organic linker of Im-MOF-3 retains the electronic properties of its molecular form, as evidenced by molecular orbital analysis.

The first study of fluxional motion in [Cu2(2-HPB)(MeCN)2Cl2] (1,2-HPB = hexa(2-pyridyl)benzene) is presented. For detailed examination of the fluxional motion mechanism, a monofluorinated derivative of the ligand (MFHPB) and its copper(i) complexes were synthesized and characterized. The solution NMR studies of monofluoro copper(i) complex 1a suggest the existence of five species in equilibrium. NMR spectra and DFT calculations suggest the fluxional motion of 1 resulting in the "metal hopping process" of two copper(i) ions.

Two hexaarylbenzenes having six pyridine substituents (LH and LM) were prepared and six corresponding coordination complexes with copper(I) chloride were synthesized. Monomeric complexes (1, 2a and 2b) and 1D coordination polymers (3, 4 and 5) were synthesized via the judicious concentration control of copper(I) ions and characterized fully by X-ray crystal analysis. The binding modes of the ligands to copper(I) ions in the coordination polymers were dependent on steric effects and solvents to determine the morphology of the coordination polymers. More interestingly, dynamic behaviours of the monomeric complexes (1, 2a and 2b) in the solution phase were studied to show potential applications of molecular machines with fluxional motions.