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A novel mixed-valence, ring-shaped multinuclear Mn-containing polyoxometalate, [H2N(CH3)2]15NaH8-[MnIII3MnIV(μ3-O)3(OAc)PO4(B-α-PW9O34)]4·36H2O (1) was made and systematically characterized using v...

Cu(I)-based catalysts have proven to play an important role in the formation of specific hydrocarbon products from electrochemical carbon dioxide reduction reaction (CO

How molecules in solution form crystal nuclei, which then grow into large crystals, is a poorly understood phenomenon. The classical mechanism of homogeneous crystal nucleation proceeds via the spontaneous random aggregation of species from liquid or solution. However, a non-classical mechanism suggests the formation of an amorphous dense phase that reorders to form stable crystal nuclei. So far it has remained an experimental challenge to observe the formation of crystal nuclei from five to thirty molecules. Here, using polyoxometallates, we show that the formation of small crystal nuclei is observable by cryogenic transmission electron microscopy. We observe both classical and non-classical nucleation processes, depending on the identity of the cation present. The experiments verify theoretical studies that suggest non-classical nucleation is the lower of the two energy pathways. The arrangement in just a seven-molecule proto-crystal matches the order found by X-ray diffraction of a single bulk crystal, which demonstrates that the same structure was formed in each case.

A new coordination polymer (CP), [(PW12O40)2CuI6(trz)6]·H2O (1), has been prepared by hydrothermal method. Six Cu(I) ions are bridged by six trz molecules and six surface oxygen atoms of PW12 to generate a wheel-type CuI6 cluster, and each CuI6 cluster was capped with two PW12 anions to form a dumbbell-like second building block (SBB). 1 can remain intact in solution with pH range from 1 to 10, boiling water and boiling organic solvents, which shows the high heat stability, acid and alkali resistance. It also shows efficient visible-light-driven photocatalytic activities in the degradation of organic dyes.

The selective epoxidation of olefins catalyzed by substituted binuclear peroxotungstates ([SeO4WO(O2)2MO(O2)2]n− (M = TiIV, VV, TaV, MoVI, WVI, TcVII, and ReVII)) are investigated at the density functional theory level. The computational results reveal that the activation barrier corresponding to the oxygen transfer to the ethylene step decreases with M = V > Ti > Ta > Mo > W > Tc > Re. The Re and Tc substituted species can effectively improve the catalytic activity with lower Gibbs free energy barriers of 22.53 and 25.82 kcal/mol relative to the others under normal conditions. This suggests that Re and Tc center peroxo complexes would improve the catalytic performance. The higher activity of the substituted species is directly attributed to the lower energy of the σ*(OO) orbital. The reaction barriers in epoxidation process are rationalized by analyzing the atomic charge, the OO bond length, and the interaction between the substituted metal and the peroxo group of the precursor complexes. © 2013 Wiley Periodicals, Inc.

Density functional theory (DFT) calculations and natural bond orbital (NBO) analysis were carried out to investigate the electronic structures and bonding features between the ruthenium(ii) atom and the SO2 molecule in two ruthenium-sulfur dioxide (SO2) adducts, trans-Ru(NH3)4(SO2)Cl(+) and [{SiW11O39}Ru(II)(SO2)](6-). In addition, the bonding interactions between SO2 and the metal-ruthenium fragment were determined by binding energy (ΔEabs) calculation and electronic structures. The results indicate that the η(1)-S-planar model in both trans-Ru(NH3)4(SO2)Cl(+) and [{SiW11O39}Ru(II)(SO2)](6-) are more favorable. NBO analysis of the bonding interaction between ruthenium and sulfur centers in the [{SiW11O39}Ru(II)(SO2)](6-) complex shows that it possesses a σ and a π bond. It predicts that the polyoxometalate [SiW11O39Ru](6-) can serve as a potential adsorbent for the SO2 molecule because of the strong Ru-S bond relative to Ru(NH3)4Cl(+).