Surface- and Structural-Dependent Reactivity of Titanium Oxide Nanostructures with 2-Chloroethyl Ethyl Sulfide under Ambient Conditions.

Robust materials capable of heterogeneous reactivity are valuable for addressing toxic chemical clean up. Synthetic manipulations for generating titanium oxide nanomaterials have been utilized to alter both photochemical (1000 nm > λ > 400 nm) and chemical heterogeneous reactivity with 2-chloroethyl ethyl sulfide (2-CEES). Synthesizing TiO2 nanomaterials in the presence of long-chain alkylphosphonic acids enhanced the visible light-driven oxidation of the thioether sulfur of 2-CEES. Photooxidation reaction rates of 99 and 168 µmol/g/h (quantum yields of 5.07 × 10-4 and 8.58 × 10-4 molecules/photon, respectively) were observed for samples made with two different alkylphosphonic acids (C14H29PO3H2 and C9H19PO3H2, respectively). These observations are correlated with (i) generation of new surface defects/states (i.e., oxygen vacancies) as a result of TiO2 grafting by alkylphosphonic acid that may serve as reaction active sites, (ii) better light absorption by assemblies of nanorods and nanowires in comparison to individual nanorods, (iii) surface area differences, and (iv) the exclusion of OH groups due to the surface functionalization with alkylphosphonic acids via Ti-O-P bonds on the TiO2. Alternatively, nanowire-form H2Ti2O5·H2O was produced and found to be capable of highly efficient hydrolysis of the carbon-chlorine (C-Cl) bond of 2-CEES in the dark with a reaction rate of 279.2 µmol/g/h due to the high surface area and chemical nature of the titanate structure.

2-Ethyl-4-methyl-1H-imidazol-3-ium bromide.

In the title mol-ecular salt, C6H11N2 +·Br-, the components are linked by N-H⋯Br⋯H-N hydrogen bonds into C(8)chains of alternating cations and anions propagating in the b-axis direction; these chains are cross-linked in the c-axis direction by weak C-H⋯Br hydrogen bonds.

The structures of 1:1 and 1:2 adducts of phosphane-tricarbo-nitrile with 1,4-di-aza-bicyclo[2.2.2]octa-ne.

In the structures of 1:1 and 1:2 adducts of phosphanetricarbo-nitrile (C3N3P) with 1,4-di-aza-bicyclo-[2.2.2]octane (C6H12N2), the 1:1 adduct crystallizes in the ortho-rhom-bic space group, Pbcm, with four formula units in the unit cell (Z' = 0.5). The P(CN)3 unit lies on a crystallographic mirror plane while the C6H12N2 unit lies on a crystallographic twofold axis passing through one of the C-C bonds. The P(CN)3 moiety has close to C 3v symmetry and is stabilized by forming adducts with two symmetry-related C6H12N2 units. The phospho-rus atom is in a five-coordinate environment. As a result of the symmetry, the two trans angles are equal so τ5 = 0.00 and thus the geometrical description could be considered to be square pyramidal. However, the electronic geometry is distorted octa-hedral with the lone pair on the phospho-rous occupying the sixth position. As would be expected from VSEPR considerations, the repulsion of the lone-pair electrons with the equatorial bonding electrons means that the trans angles for the latter are considerably reduced from 180° to 162.01 (4)°, so the best description of the overall geometry for phospho-rus is distorted square pyramidal. The 1:2 adduct crystallizes in the monoclinic space group, P21/m with two formula units in the asymmetric unit (i.e. Z' = 1/2). The P(CN)3 moiety lies on a mirror plane and one of the two C6H12N2 (dabco) mol-ecules also lies on a mirror plane. The symmetry of the P(CN)3 unit is close to C 3v. There are three P⋯N inter-actions and consequently the mol-ecular geometry of the phospho-rus atom is distorted octa-hedral. This must mean that the lone pair of electrons on the phospho-rus atom is not sterically active. For the 1:1 adduct, there are weak associations between the phospho-rus atom and one of the terminal nitro-gen atoms from the C≡ N moiety, forming chains in the a-axis direction. In addition there are weak C-H⋯N inter-actions between a terminal nitro-gen atoms from the C≡N moiety and the C6H12N2 mol-ecules, which form sheets perpendicular to the a axis.

µ-Methyl-ene-bis-[di-bromido(diethyl ether-κO)aluminium(III)]: crystal structure and chemical exchange in solution.

In the title compound, [Al2Br4(CH2)(C4H10O)2], the mol-ecule lies on a crystallographic twofold axis passing through the bridging C atom. Each AlIII atom is four-coordinate, being bonded to two bromide ions, bridging the CH2 group as well as the oxygen atom of a diethyl ether ligand in a slightly distorted tetra-hedral arrangement with angles ranging from 101.52 (8) to 116.44 (5)°. The Al-CH2-Al angle, 118.4 (2)°, is the smallest observed for a structure where this moiety is not part of a ring. In the crystal, weak C-H⋯Br inter-actions, characterized as R 2 2(12) rings, link the mol-ecules into ribbons in the [101] direction. The title compound is monomeric and coordinatively saturated in the solid state, as each aluminum is four-coordinate, but in solution the ether mol-ecules from either or both Al atoms can dissociate, and would be expected to rapidly exchange, and this is supported by NMR data.

Tetra-kis[µ2-1,1,1,3,3,3-hexa-fluoro-2-(tri-fluoro-meth-yl)propan-2-olato]tetra-kis-(µ3-2-methyl-propan-2-olato)octa-copper(I).

The title compound, [Cu8(C4H9O)4(C4F9O)4], crystallizes in the monoclinic space group, P21/n and contains a self-assembly of two C16H18Cu4F18O4 units linked by bridging tert-butyl groups [Cu-O bonds of length 2.3779 (15) and 2.4248 (15) Å], generating a centrosymmetric dimer. The asymmetrical unit, C16H18Cu4F18O4, contains an almost square-planar arrangement of the four Cu atoms linked by bridging tert-butyl and perfluorinated tert-butyl groups with Cu-Cu distances ranging from 2.7108 (4) to 2.7612 (4) Šand Cu -Cu-Cu angle values close to 90° [ranging from 89.459 (10)° to 90.025 (11)°]. These dimers are further linked by weak C-H⋯F and F⋯F inter-actions. As is commonly encountered in perfluorinated tert-butyl groups, one of the CF3 groups is disordered and was refined with two equivalent conformations with occupancies of 0.74 (3) and 0.26 (3).

Structural and theoretical studies of 4-chloro-2-methyl-6-oxo-3,6-dideuteropyrimidin-1-ium chloride (d 6).

The title compound, C5D6ClN2O+·Cl-, crystallizes in the ortho-rhom-bic space group, Pbcm, and consists of a 4-chloro-2-methyl-6-oxo-3,6-di-hydro-pyrimidin-1-ium cation and a chloride anion where both moieties lie on a crystallographic mirror. The cation is disordered and was refined as two equivalent forms with occupancies of 0.750 (4)/0.250 (4), while the chloride anion is triply disordered with occupancies of 0.774 (12), 0.12 (2), and 0.11 (2). Unusually, the bond angles around the C=O unit range from 127.2 (6) to 115.2 (3)° and similar angles have been found in other structures containing a 6-oxo-3,6-di-hydro-pyrimidin-1-ium cation, including the monclinic polymorph of the title compound, which crystallizes in the monoclinic space group P21/c [Kawai et al. (1973 ▸). Cryst. Struct. Comm. 2, 663-666]. The cations and anions pack into sheets in the ab plane linked by N-H⋯Cl hydrogen bonds as well as C-H⋯O and Cl⋯O inter-actions. In graph-set notation, these form R 3 3(11) and R 3 2(9) rings. Theoretical calculations seem to indicate that the reason for the unusual angles at the sp 2 C is the electrostatic inter-action between the oxygen atom and the adjacent N-H hydrogen.

The crystal structure of the deca-aluminum alkoxide cluster Al10O4(OH)8 L 14 (L = 1,1,1,3,3,3-hexa-fluoro-propan-2-olate).

In the title centrosymmetric cluster compound, hexa-kis-(µ2-1,1,1,3,3,3-hexa-fluoro-propan-2-olato)octa-kis-(1,1,1,3,3,3-hexa-fluoro-propan-2-olato)octa-µ2-hydroxido-di-µ4-oxido-di-µ3-oxido-deca-aluminium, [Al10(C3HF6O)14(OH)8O4] (C42H22Al10F84O26), there is a central µ4-OAl4 moiety, which has six edges of which three contain µ(O)-1,1,1,3,3,3-hexa-fluoro-propan-2-olate (L) ligands and two contain µ-OH groups each bridging two Al atoms along an edge. The sixth edge is occupied by a group containing a fifth aluminium atom [bis-µ(OH)-, µ3(O)-AlL]. This last µ3(O) group generates a centrosymmetric Al2O2 dimer, thus the µ3(O) atom is linked to two Al atoms in the asymmetric unit as well as a third Al atom through a center of inversion. Three of the hexa-fluoro-propyl groups of the C3HF6O- ligands are disordered and each was refined with two conformations with occupancies of 0.770 (3)/0.230 (3), 0.772 (3)/0.228 (3) and 0.775 (3)/0.225 (3). The five unique Al centers have coordination numbers varying from four to six with bond angles that show considerable distortions from regular geometry: for the four-coordinate atom, τ4' = 0.886, while three Al atoms are five-coordinate (τ5 values = 0.098, 1.028, and 0.338) and one is distorted six-coordinate with O-Al-O bond angles ranging from 74.22 (9) to 171.59 (12)°. The geometry about the central O atom in the OAl4 block is significantly distorted tetra-hedral (τ4' = 0.630) with Al-O-Al angles ranging from 95.50 (9) to 147.74 (13)°. The extended structure features numerous O-H⋯O, O-H⋯F, C-H⋯O and C-H⋯F hydrogen bonds and short F⋯F contacts.

Synthesis, structure, and theoretical studies of a calcium complex of a unique dianion derived from 1-methyl-pyrrolidin-2-one.

The title compound, catena-poly[[tetra-kis-(1-methyl-pyrrolidin-2-one-κO)calcium(II)]-µ-(E)-1,1'-dimethyl-2,2'-dioxo-1,1',2,2'-tetra-hydro-[3,3'-bipyrrolyl-idene]-5,5'-bis-(thiol-ato)-κ2 O:O'], [Ca(C10H8N2O2S2)(C5H9NO)4] n , 1, crystallizes in the triclinic space group P . The crystal studied was twinned by non-merohedry via two different twofold operations, about the normals to (001) and (10), giving four twin domains with refined occupancies of 0.412 (4), 0.366 (4), 0.055 (1), 0.167 (4). The Ca atoms are located on centers of inversion. Each Ca is surrounded by four 1-methyl-pyrrolidin-2-one (NMP) ligands and coordinated through one of the two O atoms to two (E)-1,1'-dimethyl-2,2'-dioxo-1,1',2,2'-tetra-hydro-[3,3'-bipyrrolyl-idene]-5,5'-bis-(thiol-ate), [C10H8N2O2S2]2-, dianions (abbreviation: DMTBT). This dianion thus facilitates the formation of a 1-D polymer, which propagates in the [011] direction. These ribbons are linked by inter-molecular C-H⋯S inter-actions. Each Ca atom is in an octa-hedral CaO6 six-coordinate environment with Ca-O bond lengths ranging from 2.308 (6) to 2.341 (6) Å, cis bond angles ranging from 88.2 (2) to 91.8 (2)° and the trans angles all 180° due to the Ca atoms being located on centers of inversion. Theoretical calculations were carried out using density functional theory (DFT) and the results showed that although the central DMTBT dianion is planar there is likely some resonance across the central bond between both aza-pentyl rings, but this is not sufficient to establish a ring current. The calculated UV-vis spectrum shows a peak at 625 nm, which accounts for the deep blue-purple color of solutions of the complex.

Tetra-methyl-ammonium (Z)-N'-cyano-carbamimidate.

In the structure of the tetra-methyl ammonium salt of cyano-urea, C4H12N+·C2H2N3O-, the N-C and O-C bond distances in the cyano and keto groups are in the normal range for such a moieties at 1.1641 (18) and 1.2550 (16) Å. However, the bonds about the central C and N atoms are much shorter than would be expected for single bonds and indicate that there is considerable electron delocalization in the anion as was also found in the silver salt. The NH2 group is coplanar with the central N2CO core, in contrast with the nitrile group where the dihedral angle between the N-C-N and N2CO planes is 36.5 (3)°. The packing of the cations and anions in the unit cell involves N-H⋯O hydrogen bonds between anions characterized by an R 2 2(8) motif, as well as N-H⋯O hydrogen bonds between anions and C-H⋯O inter-actions between both cations and anions, forming an R 3 3(14) pattern.

Potassium chlorido-tris-(hypersil-oxy)aluminate dimer.

The tris-(tri-methyl-silylsiloxide) ligand, also known as hypersiloxide, is an extremely bulky group. In an attempt to make the monomeric Al(OSi(SiMe3)3)3, AlCl3 was combined with 3 equiv. of potassium hypersiloxide. The crystalline product isolated (40% yield), namely di-µ3-chlorido-bis-[µ2-tris-(tri-methyl-sil-yl)silanolato]tetra-kis-[tris-(tri-methyl-sil-yl)silanolato]dialuminium-dipotassium, [Al2K2Cl2(C19H27OSi4)6], is a KCl adduct of aluminium tris(hypersilyloxide) that is dimerized through a planar K2Cl2 ring, with K-Cl distances of 3.1131 (8) and 3.319 (3) Å, and ring angles of 77.41 (2) and 102.60 (2)°. This ring is on an inversion center, and there is no supra-molecular coordination.

Synthesis and Structure of Sn14Cl6(CH2SiMe3)12: Toward Nanoclusters of 4-Coordinate α-Sn.

Orange crystals of a Sn14 cluster have been isolated in up to 22% yield from a reaction between Me3SiCH2SnCl3, SnCl4, and LiAlH4. The structure determined by single crystal X-ray diffraction shows three unique Sn atoms in a 6:6:2 ratio, with all Sn atoms 4-coordinate, similar to the tetrahedral bonding in elemental gray Sn. The solid state 117Sn MAS NMR spectrum shows the three types of distinct Sn atoms in the expected 3:3:1 intensity ratio with respective chemical shifts of 87.9, -66.6, and -607.1 ppm relative to Me4Sn. The chemical shift of the two Sn atoms without ligands (bonded only to Sn), at -607.1 ppm, is the most upfield, and is the closest to the chemical shift, reported here, of bulk gray tin (-910 ppm). First-principles density functional theory calculations of the chemical shielding tensors corroborate this assignment. While the core coordination is distorted from the ideal tetrahedral arrangement in the diamond structure of gray tin, this Sn14 cluster, as the largest reported cluster with all 4-coordinate Sn, represents a major incremental step toward being able to prepare atomically precise nanoparticles of gray tin.

High-pressure phase transition of alkali metal-transition metal deuteride Li2PdD2.

A combined theoretical and experimental study of lithium palladium deuteride (Li2PdD2) subjected to pressures up to 50 GPa reveals one structural phase transition near 10 GPa, detected by synchrotron powder x-ray diffraction, and metadynamics simulations. The ambient-pressure tetragonal phase of Li2PdD2 transforms into a monoclinic C2/m phase that is distinct from all known structures of alkali metal-transition metal hydrides/deuterides. The structure of the high-pressure phase was characterized using ab initio computational techniques and from refinement of the powder x-ray diffraction data. In the high-pressure phase, the PdD2 complexes lose molecular integrity and are fused to extended [PdD2]∞ chains. The discovered phase transition and new structure are relevant to the possible hydrogen storage application of Li2PdD2 and alkali metal-transition metal hydrides in general.

Pressure-Induced Polymerization of LiN(CN)2.

The high-pressure behavior of lithium dicyanamide (LiN(CN)2) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time. On the basis of spectroscopic and diffraction data, we suggest a polymorphic phase transformation at ∼8 GPa, wherein dicyanamide ions remain as discrete molecular species. Above ca. 18 GPa, dicyanamide units polymerize, forming a largely disordered network, and the extent of polymerization may be increased by annealing at elevated temperature. The polymerized product consists of tricyanomelaminate-like groups containing sp2-hybidized carbon-nitrogen bonds and exhibits a visible absorption edge near 540 nm. The product is recoverable to ambient conditions but is not stable in air/moisture.

Poly[tetrakis(µ-1,1,1,3,3,3-hexafluoropropan-2-olato)iron(II)dipotassium].

The title compound, [K2Fe{OCH(CF3)2}4] n , was formed from the reaction of potassium hexa-fluoro-isopropoxide with iron(II) chloride in toluene. The Fe(II) atom has a highly distorted tetra-hedral coordination environment. All four of the non-equivalent hexa-fluoro-isoprop-oxy O atoms link the Fe(II) atoms to one of the K(+) atoms in an alternating chain of Fe-O-K-O fused four-membered rings, with K-Fe distances of 3.715 (2) and 3.717 (2) Å. This K(+) atom is also bridged to eight of the F atoms. The other K(+) atom is bonded to only two of the O atoms, but has seven short K⋯F contacts, one of which links the chains into a three-dimensional arrangement. Weak hydrogen bonding between the lone H atoms on the hexa-fluoro-isoprop-oxy groups and F atoms is also present. The crystal studied was refined as an inversion twin.

Bis(η(5)-penta-methyl-cyclo-penta-dien-yl)aluminium tetra-bromido-aluminate.

The title compound, [Al(C10H15)2][AlBr4], was formed during the reduction of a mixture of Cp*AlBr2 and AlBr3. The Al(III) atoms of the two crystallographically independent cations each lie on an inversion center, and the [AlBr4](-) anions are on general positions. At 123 K, the structure exhibits disorder in two of the Br atoms of the [AlBr4](-) ion, with a ratio occupancy of 0.733 (6): 0.267 (3). In the crystal, there is possible weak hydrogen bonding between some methyl groups and Br atoms. The interactions link the moieties in a three-dimensional array.

Di-aqua-bis-(2-ethyl-5-methyl-imidazole-4-sulfonato-κ(2) N (3),O)nickel(II) dihydrate.

In the title complex, [Ni(C6H9N2O3S)2(H2O)2]·2H2O, the Ni(II) atom lies on an inversion center and is chelated by N and O atoms of two symmetry-equivalent imidazole-sulfonate ligands in the basal plane, and two water O atoms in axial positions in an overall octa-hedral configuration. The crystal structure displays O-H⋯O and N-H⋯O hydrogen bonds, which connect the components into an extended three-dimensional network.

Thermodynamic and kinetic stabilities of CO2 oligomers.

Density-functional and coupled cluster calculations suggest that the stability, against unimolecular dissociation, of the cyclic D(3h) trimer of CO2, 1,3,5-trioxetanetrione, is greater than all but one other chemically bound oligomer of CO2. It requires far less energy to produce, on a per CO2 basis, than the low-symmetry cyclic 1,2 dioxetanedione dimer, but its kinetic stability against unimolecular dissociation is much lower. The extreme stability of the dimer, which makes it an excellent intermediate in chemiluminescence, is caused by an extreme range of geometric change to its transition state leading to a trapezoidal potential energy surface. The thermodynamically more stable trimer affords a low pressure pathway from molecular carbon dioxide to the extended covalent structure at high pressure.

Triclinic polymorph of bis-(triphenyl-sil-yl) oxide toluene disolvate.

A new polymorph of the title compound, C(36)H(30)OSi(2)·2C(7)H(8), is reported, which is triclinic (P-1) instead of possessing the previously reported rhombohedral symmetry [Hönle et al. (1990). Acta Cryst. C46, 1982-1984]. Each of the -SiPh(3) units are related by the inversion center. The Si-O-Si moiety is linear with the O atom sitting on an inversion center, and the O-Si-(toluene ring centroid) angle is 3.69 (15)°. Each toluene mol-ecule is 5.622 (2) Šfrom the Si atom and has its closest contacts with the phenyl rings outside of the van der Waals radii.

catena-Poly[copper(II)-bis-(µ-2-ethyl-5-methyl-imidazole-4-sulfonato-κN,O:O)].

In the title compound, [Cu(C(6)H(9)N(2)O(3)S)(2)](n), the copper(II) ion sits on an inversion center and is chelated by the imidazole N and sulfonate O atoms of two ligands in equatorial positions. O atoms of adjacent mol-ecules coordinate in the axial positions. Jahn-Teller tetra-gonal distortion is evident in the coordination geometry [Cu-N and Cu-O equatorial distances of 1.971 (3) and 2.045 (2) Å, respectively, with a Cu-O axial distance of 2.433 (3) Å]. The structure is propagated by an infinite chain of eight-membered (Cu-O-S-O)(2) ring systems along the a axis. Only N-H⋯O hydrogen bonding exists between the chains.

Sulfonated 1,3-bis-(4-pyrid-yl)propane.

In the title compound, 4-[3-(3-sulfonato-pyridin-1-ium-4-yl)prop-yl]pyridin-1-ium-3-sulfonate, C(13)H(14)N(2)O(6)S(2), the mol-ecule is zwitterionic, with the sulfonic acid proton transfered to the basic pyridine N atom. Also, the structure adopts a butterfly-like conformation with the sulfonate groups on opposite sides of the 'wings'. The dihedral angle between the two pyridinium rings is 83.56 (7)°, and this results in the mol-ecule having a chiral conformation and packing. There is strong inter-molecular hydrogen bonding between the pyridinium H and sulfonate O atoms of adjoining mol-ecules. In addition, there are weaker inter-molecular C-H⋯O inter-actions.