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Hai-Shun Wu

Publications and source records attributed to Hai-Shun Wu.

14 recordsLinked to original sources
PubMed2007

Structural and electronic properties of hetero-transition-metal Keggin anions: a DFT Study of alpha/beta-[XW12O40]n- (X = CrVI, VV, TiIV, FeIII, CoIII, NiIII, CoII, and ZnII) relative stability.

Density functional theory calculations have been carried out to investigate the electronic structures and the alpha/beta relative stability of Keggin-typed [XW(12)O(40)]n- anions with transition metal as heteroatom X (X = Cr(VI), V(V), Ti(IV), Fe(III), Co(III), Ni(III), Co(II) and Zn(II)). Nice agreement in geometries between computation and experiment has been obtained, and the higher stability of the alpha isomer over the beta one has been confirmed. Structural parameter analysis reveals that the {M(3)O(13)} triads in both alpha and beta isomers contract considerably with the increase of the negative anionic charge, while the overall size of both isomers shrinks only slightly. Fragment molecular orbital analysis shows that except alpha/beta-[TiW(12)O(40)]4-, the electronic structures of Keggin anions can be described by the insertion of the e and/or t2 orbital of XO4n- into the frontier orbitals of W(12)O(36) cage, and this leads to the specific redox property, which is different from that of the Keggin anions with main-group elements as heteroatoms. Energy decomposition analysis shows that the enhanced intrinsic stability of the alpha isomer in Td arrangement of W(12)O(36) shell and the larger deformation of the alpha over the beta isomer are two dominating factors and contribute oppositely to the alpha/beta relative stability.

Journal Article↗
PubMed2006

Localized and delocalized perfluorosemibullvalenes.

On the basis of the experimental Gibbs free-energy barrier of the degenerate Cope arrangement in semibullvalene, B3P86 shows the best agreement, while B3LYP and MP2 underestimate and CCSD(T) overestimates the barrier. The substituent effect proposal by Hoffmann has been verified. In contrast to semibullvalenes with either localized energy-minimum structures or delocalized transition-state structures, perfluorosemibullvalene has both localized and delocalized energy-minimum structures that are very close in energy.

Base Pairing↗
PubMed2006

Structure and stability of neutral polyoxometalate cages: (Mo2O6)m (m=1-13).

The structure and stability of neutral polyoxometalate cages (Mo2O6)m (m=1-13) have been computed systematically. These neutral cages can be viewed topologically as polyhedra containing triangles (f3) and squares (f4). The relative stability of these polyhedra is associated with the location and separation of the f3. The initial stable isomers were preselected by the number of shared triangle edges (N33), and the predicted stability was validated further at the GGA-PW91/DND level of density function theory with the fine quality of mesh size. For large clusters, the square neighbor signature (P4444), which is similar to the hexagon neighbor rule for fullerene, becomes more applicable. The calculated disproportionation energies indicate that Mo6O18 (O(h), Lindqvist), Mo12O36 (O(h), alpha Keggin), Mo18O54 (D(3h), Wells-Dawson) and Mo24O72 (O(h)) cages have enhanced stability. [structure in text]. Mo6O18 (O(h)), Mo12O36 (O(h)), Mo18O54 (D(3h)) and Mo(24)O72 (O(h)) are the most stable neutral polyoxometalate cages on the basis of the structural and energetic criteria. They can therefore be considered as the inorganic fullerenes.

Electrons↗
PubMed2006

Boron nitride cages from B12N12 to B36N36: square-hexagon alternants vs boron nitride tubes.

The structures and stabilities of square-hexagon alternant boron nitrides (Bx Nx , x=12-36) vs their tube isomers containing octagons, decagons and dodecagons have been computed at the B3LYP density functional level of theory with the correlation-consistent cc-pVDZ basis set of Dunning. It is found that octagonal B20N20 and B24N24 tube structures are more stable than their square-hexagon alternants by 18.6 and 2.4 kcal mol(-1), respectively, while the square-hexagon alternants of other cages are more stable. Trends in stability as a function of cluster size are discussed.

Boron Compounds↗
PubMed2006

Syntheses and structures of metal tetrazole coordination polymers.

Two salts and seven copper(I/II) and silver(I) coordination polymers containing tetrazolyl ligands have been hydro(solvo)thermal synthesized by metal salts, NaN3 and various nitriles generated via [2 + 3] cycloaddition reactions of organonitriles and sodium azide. The study also shows that in some cases the azide can play a dual role in the in situ syntheses of metal tetrazole complexes, namely, starting material for tetrazole ligand and co-ligand in the tetrazole-based coordination complexes. Compounds and are simple salts of ammonium and sodium 5-methyltetrazolate. Compound has a 3-D framework with intersecting channel and unprecedented (4(9).6(6)) topology constructed from mixed-valent Cu8 clusters. Compounds and are isomorphous, and have 3-D organic-inorganic frameworks constructed by [M2(mtta)]+ (Hmtta = 5-methyltetrazole) ribbon and [M2(N3)]+ (M = Cu, Ag) layer two types of structural motifs, which contains an mu(4)-1,1,1,3 azide. Compound is a 3-D four-connected chiral complex with (4(2).8(4))(Cu)(4(2).8(2).10(2))(tta) topology. The structure of consists of 2-D three-connected layers that are linked by ligand-unsupported Ag(I)...Ag(I) interactions to form a 3-D supramolecular array. Compound shows a 3-D chiral framework containing tetrahedrally and linearly coordinated Ag(I) ions and mu3- and mu4-two types of 5-propyltetrazolate. Compound has a 2-D layered structure formed by linkage of [Ag(tetrazolyl)] ribbons via C-C and N-Ag bonds. Magnetic measurement confirmed that there are two Cu(II) ions and six Cu(I) ions per Cu8 unit consistent with a mixed-valent Cu(I,II) complex.

Journal Article↗
PubMed2005

The structure and stability of B36N36 cages: a computational study.

The structure and stability of 22 B36N36 cage molecules containing four-membered (F4), five-membered (F5), six-membered (F6), eight-membered (F8) and 12-membered (F12) rings have been computed at the B3LYP/6-31G* level of density functional theory. The most stable structure (1) has T(d) symmetry with six F4 and 32 F6 rings, following the isolated square rule, while the fullerene-like structures (12 F5 and 26 F6) and also structures with F8 and F12 are much higher in energy. Figure The T(d) symmetrical structure (1) with six F4 and thirty-two F6 rings is the most stable B36N36 cage.

Carbon↗
PubMed2005

Cuprophilicity-induced cocrystallization of [Cu2(4,4'-bpy)(CN)2]n sheets and [Cu(SCN)]n chains into a 3-D pseudopolyrotaxane.

The cocrystallization of [Cu(SCN)]n chains and [Cu2(4,4'-bpy)(CN)2]n (4,4'-bpy = 4,4'-bipyridine) layers generated a 3-D pseudopolyrotaxane compound, [Cu2(4,4'-bpy)(CN)2].[Cu(SCN)] (1), which can also be viewed as a 3-D network constructed by linkages of 2-D sheets and 1-D chains via unsupported CuI-CuI interactions. The CuI-CuI contact of 2.651(4) A in 1 is the shortest unsupported CuI-CuI distance documented to date, indicating cuprophilic attractions.

Journal Article↗
PubMed2005

A twelve-connected Cu6S4 cluster-based coordination polymer.

Hydrothermal reaction of Cu(MeCO2)2, (4-pyridylthio)acetic acid, and NH4SCN resulted in a metal-organic framework [Cu3(4-pyridinethiolate)2(CN)] which has twelve-connected face-centered cubic topology with Cu6S4 clusters as nodes.

Journal Article↗
PubMed2005

Structures and energies of isolobal (BCO)n and (CH)n cages.

The structures and energies of isolobal (CH)n and (BCO)n polyhedral species, computed at the B3LYP density functional theory level, reveal contrasts in behavior. The strain energies of the (BCO)n cages are much smaller. Also unlike the (CH)n cages, the most stable (BCO)n polyhedra (n > or = 10) prefer structures with the largest number of three-membered rings. The planar (or nearly planar) faces of the cage systems were modeled by computations on planar, isoelectronic (CH2)n (Dnh) and (HBCO)n (Cnv) rings. While the strain energies of all the planar carbon rings, relative to the most stable D5h (CH2)5, were large, the strain energies of all the planar (HBCO)n (Cnv) rings were small. Remarkably, the three-membered (HBCO)3 (C3v) ring was the most stable. Finally, large (BCO)n systems prefer tubelike rather than cage structures.

Journal Article↗
PubMed2004

In situ formation of meso-2,2'-oxydisuccinate via intermolecular dehydration coupling of D,L-malic acid: first coordination polymer of 2,2'-oxydisuccinate involving ether oxygen coordination: [Cd2(meso-odsc)(H2O)].

The first coordination polymer of 2,2'-oxydisuccinate, [Cd(2)(meso-odsc)(H(2)O)](odsc =meso-2,2'-oxydisuccinate), was hydrothermally synthesized from CdSO(4) and D,L-malic acid; X-ray crystallography shows that the D,L-malic acid was transformed in situ into meso-odsc via intermolecular dehydration coupling.

Journal Article↗
PubMed2003

Neutral bishomoaromatic semibullvalenes.

Isolobal substitution of CH units by boron carbonyl groups (BCO) at C2,6 and C2,8,4,6 in semibullvalene favors the delocalized neutral bishomoaromatic systems substantially. The homoaromaticity is documented by the computed diatropic nucleus independent chemical shifts (NICS). In addition, BCO substitution can result in low-lying triplet and open-shell singlet states. In contrast, substitution at C1,5 more than doubles the related Cope rearrangement barrier. The C2,6 and C2,8,4,6 BCO-substituted barbaralanes, barbaralones, and bullvalenes have substantially reduced barriers.

Journal Article↗
PubMed2003

Monocyclic boron carbonyls: novel aromatic compounds.

Monocyclic boron carbonyls, (BCO)nm, with 4n + 2 delocalized electrons are highly aromatic, as indicated by the computed nucleus independent chemical shift (NICS) and the computed energies for benzene analogue.

Journal Article↗
PubMed2003

Are neutral oxocarbons stable?

A set of novel oligomeric polycyclic neutral oxocarbons has been computed at the B3LYP level of density functional theory. On the basis of the calculated dissociation enthalpies, the most stable structures are C(9)O(9) and C(12)O(12) with benzene-like central ring, in agreement with the experimental finding, and the enhanced stability is due to their aromaticity. Several other oxocarbons also have been identified as stable and are targets for further experimental investigations.

Journal Article↗