Prismatic Environment Research Articles

Novel tris-o-semiquinonato cobalt complexes, where quinonato fragments are modified by cyclic substituents

Octacarbonyldicobalt reacts with tricyclic 5,8-di(tert-butyl)-2,3-dihydro-1,4-ethanoquinoxaline-6,7-dione and 5,8-di-tert-butyl-2,3-dihydrobenzo[b][1,4]dioxine-6,7-dione to give tris-o-semiquinonato complexes (1 and 2, respectively). X-ray structural study indicate exact trigonal prismatic environment of cobalt in 1 and slightly twisted one in 2. Rigid and flexible steric configurations of N,N′-piperazino- and O,O′-ethane-1,2-diolato-cyclic fragments of ligands are responsible for trigonal prismatic molecular geometry of 1 and twisted one for 2. Magnetic moment temperature dependences have very close shapes for 1 and 2 and correspond to S=1/2 ground state. High temperature limits exceed spin-only value calculated for three noninteracting spins on three semiquinones. Precision calorimetric study of temperature dependence of heat capacity of 1 does not detect significant anomalies.

Poly[[tetraaqua-μ4-fumarato-di-μ3-fumarato-dineodymium(III)] trihydrate

The title coordination polymer, {[Nd2(C4H2O4)3(H2O)4]·3H2O}, was synthesized by the reaction of neodymium(III) nitrate hexa­hydrate with fumaric acid in a water–methanol (7:3) solution. The asymmetric unit comprises two Nd3+ cations, three fumarate dianions (L 2−), four aqua ligands and three uncoordinated water mol­ecules. The carboxyl­ate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups chelate two Nd3+ cations, while one of the O atoms is coordinated to another Nd3+ cation. Another fumarate dianion bridges three Nd3+ cations: one of the carboxyl­ate groups chelates one Nd3+ cation, while the other carboxyl­ate group bridges two Nd3+ cations in a monodentate mode. The third fumarate dianion bridges four Nd3+ cations, where one of the carboxyl­ate groups chelates one Nd3+ cation and coordinates in a monodentate mode to a second Nd3+, while the second carboxyl­ate groups bridges two Nd3+ cations in a monodentate mode and one O atom is coordinated to one Nd3+ cation. The Nd3+ cations are in a distorted tricapped–trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water mol­ecules. The Nd3+ cations are linked by two carboxyl­ate O atoms and two carboxyl­ate groups, generating infinite Nd–O chains to form a three-dimensional framework. There are O—H⋯O and C—H⋯O hydrogen-bonding interactions between the coordin­ated and uncoordinated water mol­ecules and carboxyl­ate O atoms.

Poly[diaquabis(μ4-fumarato-κ4O1:O1′:O4:O4′)(μ4-fumarato-κ6O1:O1,O1′:O4:O4,O4′)(μ2-fumaric acid-κ2O1:O4)dipraseodymium(III)

The title complex, [Pr2(C4H2O4)3(C4H4O4)(H2O)2]n, was synthesized by reaction of praseodymium(III) nitrate hexa­hydrate with fumaric acid in a water–ethanol (4:1) solution. The asymmetric unit comprises a Pr3+ cation, one and a half fumarate dianions (L 2−), one half-mol­ecule of fumaric acid (H2L) and one coordinated water mol­ecule. The carboxyl­ate groups of the fumarate dianion and fumaric acid exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups are chelating with two Pr3+ cations, and the other two O atoms each coordinate a Pr3+ cation. Each O atom of the second fumarate dianion binds to a different Pr3+ cation. The fumaric acid employs one O atom at each end to bridge two Pr3+ cations. The Pr3+ cation is coordinated in a distorted tricapped trigonal–prismatic environment by eight O atoms of fumarate dianion or fumaric acid ligands and one water O atom. The PrO9 coordination polyhedra are edge-shared through one carboxyl­ate O atom and two carboxyl­ate groups, generating infinite praseodymium–oxygen chains, which are further connected by the ligands into a three-dimensional framework. The crystal structure is stabilized by O—H⋯O hydrogen-bond inter­actions between the coordin­ated water mol­ecule and the carboxyl­ate O atoms.

Tetrakis(μ-4-tert-butylbenzoato)-κ3O:O,O′;κ3O,O′:O′;κ4O:O′-bis[aquabis(4-tert-butylbenzoato-κ2O,O′)(4-tert-butylbenzoic acid-κO)praseodymium(III)

The reaction of praseodymium nitrate and 4-tert-butyl­benzoic acid (tBBAH) in aqueous solution yielded the dinuclear title complex, [Pr2(C11H13O2)6(C11H14O2)2(H2O)2], which has non-crystallographic Ci symmetry. The two PrIII ions are linked by two bridging and two bridging–chelating tBBA ligands, with a Pr⋯Pr separation of 4.0817 (9) Å. Each PrIII ion is nine-coordinated by one chelating tBBA ion, one monodentate tBBAH ligand and one water mol­ecule in a distorted tricapped trigonal–prismatic environment. The complex mol­ecules are linked into infinite chains along the c axis by inter­molecular O—H⋯O hydrogen bonds.

Poly[[diaqua-μ6-succinato-di-μ5-succinato-didysprosium(III)] monohydrate

The title compound, {[Dy2(C4H4O4)3(H2O)2]·H2O}n, is isostructural with other lanthanide succinates of the same formula. The DyIII atom is nine-coordinated in a tricapped trigonal–prismatic environment by eight O atoms, derived from six carboxyl­ate groups and a water mol­ecule. One of the independent succinate anions is located about a crystallographic inversion center and the uncoordinated water mol­ecule lies on a twofold axis. The crystal structure comprises edge-shared DyO9 polyhedra linked by succinate bridges, forming a three-dimensional network architecture. Intra- and inter­molecular O—H⋯O hydrogen bonds are present in the crystal structure.

Tetrakis(μ-4-tert-butylbenzoato)-κ4O:O′;κ3O,O′:O′;κ3O:O,O′-bis[aqua(4-tert-butylbenzoato-κ2O,O′)(4-tert-butylbenzoic acid-κO)neodymium(III)

The reaction of neodymium nitrate and 4-tert-butyl­benzoic acid (tBBAH) in aqueous solution yielded the dinuclear title complex, [Nd2(C11H13O2)6(C11H14O2)2(H2O)2], which has non-crystallographic Ci symmetry. The two NdIII ions are linked by two bridging and two bridging–chelating tBBA ligands with an Nd⋯Nd separation of 4.0624 (5) Å. Moreover, each NdIII ion is coordinated by one chelating tBBA ion, one monodentate tBBAH ligand and one water mol­ecule. The nine-coordinated NdIII ion is in a distorted tricapped trigonal–prismatic environment. The mol­ecules are linked into infinite chains along the c axis by inter­molecular O—H⋯O hydrogen bonds. Three of the tert-butyl groups are disordered over two sets of sites with equal occupancies.

Experimental and theoretical properties of S–Mo–Co–S clusters

In this work we propose that certain structures found in real commercial catalysts may be related to low dimensional structures. These structures are S–Mo–S and S–Mo–Co–S nanowires which were characterized by High Resolution Scanning Transmission Electron Microscopy (HR-STEM), Electron Diffraction (ED) and Electron Dispersive X-ray analysis (STEM-EDAX). Furthermore, a structural model was constructed with the one dimensional structures in order as to investigate their electronic properties. Energy band analysis on the samples yield indication about the semi metallic behavior, while a careful analysis to the partial Density of States (PDOS) in the vicinity of the Fermi level, provided indication for the existence of strong hybridization between S p- with Mo d- and Co d- and p-orbitals for the samples enunciated formerly. In addition, a very important issue to be mentioned is that in the construction of the 1T-S–Mo–Co–S nanowires, the Co and Mo atoms are not in their pure trigonal prismatic environment as compared to the bulk 2H-MoS 2. This issue could be deleterious for future catalytic applications.

Molecular models for WH6 under pressure

At atmospheric pressure, some tungsten hydrides exist as discrete molecular complexes in low temperature matrices, but are very reactive and cannot be isolated in bulk at room temperature. Under pressure, one observes WH in experiment at room temperature, and calculations indicate several other stoichiometries are stable, all extended and not molecular. This work aims at constructing a bridge between discrete molecules and the pressurized extended structures, with the emblematic example of WH6. The equilibrium structure, known as a distorted trigonal prismatic molecule, is likely to be a good acceptor. In numerical experiments, discrete WH6 molecular complexes are allowed to interact with each other in their ground states at T = 0 K and P = 1 atm. They spontaneously rearrange to form 1D-chains, with the W centers adopting a tricapped trigonal prismatic environment. The electronic structure of these chains is examined and related to that of the monomer and extended solids.

Alkali Metal Ion Complexes with Pyrazinetetracarboxylate: Two- and Three-Dimensional Frameworks

Three novel polymeric assemblages have been obtained from alkali metal salts of pyrazinetetracarboxylic acid (H4PZTC). In the complexes [Na2(H2PZTC)(H2O)2] (1), [K(H3PZTC)] (2), and [Cs2(H2PZTC)] (3), the cations are chelated in the O,N,O site of one (1) or two ligands (2 and 3),and further carboxylic/ate complexation results in the formation of two- (1) or three-dimensional (2 and 3) compact assemblages with alternate rows or planes of cations and ligands. The H4−xPZTCx− ligand is bound to 6, 4, and 12 cations in 1−3, respectively, with four oxygen atoms in the last case being coordinated to as many as four cesium atoms each. The crystal structure of complex 3 is particularly remarkable, with the cesium cation having a coordination number of 12 and a hexagonal prismatic environment. The Cs···Cs contacts in this compound are among the shortest reported. These compounds further illustrate the potential of H4PZTC for the building of metal−organic frameworks.

The new ternary phases of La3(Zn0.874Mg0.126)11and Ce3(Zn0.863Mg0.137)11

The new ternary intermetallic title compounds, namely trilanthanum undeca(zinc/magnesium), La(3)(Zn(0.874)Mg(0.126))(11), (I), and tricerium undeca(zinc/magnesium), Ce(3)(Zn(0.863)Mg(0.137))(11), (II), are isostructural and crystallize in the orthorhombic La(3)Al(11) structure type. These three phases belong to the same structural family, the representative members of which may be derived from the tetragonal BaAl(4) structure type by a combination of internal deformation and multiple substitution. Compared to the structure of La(3)Al(11), in (I), a significant decrease of 11.9% in the unit-cell b axis and an increase in the other two directions, of 3.6% along a and 5.2% along c, are observed. Such an atypical deformation is caused by the closer packing of atoms in the unit cell due to atom shifts that reflect strengthening of metallic-type bonding. This structural change is also manifested in a significant difference in the coordination around the smaller atoms at the 8l Wyckoff position (site symmetry m). The Al atom in La(3)Al(11) is in a tricapped trigonal prismatic environment (coordination number 9), while the Zn atoms in (I) and (II) are situated in a tetragonal antiprism with two added atoms (coordination number 10).

Pr4S3[AsS3]2: Praseodym(III)‐Sulfid‐Thioarsenat(III) mit Ketten und Schichten aus kondensierten [SPr4]‐Tetraedern

AbstractSingle crystals of Pr4S3[AsS3]2 can be obtained through the reaction between the elements praseodymium, arsenic and sulfur using CsCl as fluxing agent in torch‐sealed evacuated silica ampoules. The starting materials were heated for ten days at 700 °C and then cooled down slowly to room temperature. The transparent, pale greenish yellow platelets crystallize orthorhombically (a = 2910.6(2), b = 699.74(5), c = 704.51(5) pm) in space group Pbcn (no. 60) with Z = 4. The new compound Pr4As2S9 (≡ Pr4S3[AsS3]2) contains two crystallographically independent Pr3+ cations. (Pr1)3+ shows a bicapped trigonal prismatic environment of eight sulfur atoms (CN = 8), whereas (Pr2)3+ is surrounded by only seven sulfur atoms in the shape of a monocapped trigonal prism (CN = 7). The isolated pyramidal thioarsenate(III) anions [AsS3]3– are formed as ψ1‐tetrahedra by the three sulfur atoms (d(As3+–S2–) = 223–228 pm, ∢(S–As–S) = 94–104°) and a non‐binding electron pair (lone pair) at each As3+ cation. Two of the five crystallographically different sulfur atoms (S1 and S2) are not connected to As3+ at all, but coordinated by four Pr3+ cations each to build up slightly distorted [SPr4]10+ tetrahedra (d(S2––Pr3+) = 281–289 pm, ∢(Pr–S–Pr) = 98–146°). Thus the crystal structure of Pr4S3[AsS3]2 exhibits endless {}^1_∞{[(S1)Pr4/2]4+} chains and {}^2_∞{[(S2)Pr4/4]+} layers, which consist of trans‐edge condensed [(S1)Pr4]10+ tetrahedra for the chains and [(S2)Pr4]10+ tetrahedra sharing four common edges for layers. The lone pairs at the As3+ cations close around the{}^1_∞{[(S1)Pr4/2]4+} chains running along [001]. The {}^2_∞{[(S2)Pr4/4]+} layers spread out parallel to the (100) plane and complete the crystal structure of Pr4S3[AsS3]2 according to {}^1_∞{[(S1)(Pr1)4/2]4+}{}^2_∞{([(S2)(Pr2)4/4]+)2} {}^0_∞{([As(S3)(S4)(S5)]3–)2}.

Pr2CBr: Ein Ferromagnet mit Pr2C-Schichten/ Pr2CBr: A Ferromagnet with Pr2C Layers

Single-phase Pr2CBr was prepared by heating a mixture of PrBr3, Pr and C (1 : 5:3) to 1140 °C for 18 d. The crystal structure was investigated by X-ray single crystal diffraction (space group P63/mmc, a = 3.8071(3), c = 14.7787(12) Å). In the structure the Pr atoms form C-centered octahedra condensed into Pr2C sheets via common edges; these sheets are separated by the Br atoms which are in a trigonal prismatic environment of Pr atoms. Pr2CBr is a black shiny compound with metallic conductivity. It is a ferromagnet with Tc = 13.8(5) K.

ChemInform Abstract: BaIrIn4 and Ba2Ir4In13: Two In‐Rich Polar Intermetallic Structures with Different Augmented Prismatic Environments about the Cations.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

BaIrIn4and Ba2Ir4In13: Two In-Rich Polar Intermetallic Structures with Different Augmented Prismatic Environments about the Cations

The title phases were synthesized via high-temperature reactions of the elements in welded Ta tubes and characterized by single-crystal X-ray diffraction methods and band calculations. BaIrIn4 adopts the LaCoAl4-type structure: Pmma, Z = 2, a = 8.642(2), b = 4.396(1), and c = 7.906(2) A. Ba2Ir4In13 exhibits a new structure type: Cmc2(1), Z = 4, a = 4.4856(9), b = 29.052(6), and c = 13.687(3) A. BaIrIn4 is constructed from a single basic unit, a Ba-centered pentagonal prism of indium on which two adjacent and the opposed rectangular faces are capped by In and Ir, respectively. The three capping atoms are coplanar with Ba and represent the only augmentation of the pentagonal prism. The relatively large proportions of Ba:Ir, In, and of In:Ir lead to the condensation of homoatomic pentagonal prisms into zigzag chains through the sharing of the two uncapped faces. The cation proportion is much lower in Ba2Ir4In13, and Ba atoms are surrounded by a more anionic Ir/In network without any condensation between prisms. This and the greater Ir proportion lead to a network of formal augmented pentagonal Ba@Ir5In15 and hexagonal Ba@Ir7In15 prisms with overall 5-10-5 and 6-10-6 arrangements of parallel planar rings, respectively, although most Ir is not well bound to the prisms. The latter prism, with alternating Ir/In atoms in the basal faces, is novel for Ae-T-In phases (Ae = alkaline-earth metal, T = Co, Rh, Ir). Band structure calculation results (linear-muffin-tin-orbital method in the atomic sphere approximation) emphasize the greater overlap populations (approximately strengths) of the Ir-In bonds and confirm expectations that both compounds are metallic. The Ir 5d bands are narrower and lie higher in energy than those for Au in analogous phases.

C 4− carbide ligand in the trigonal prismatic environment of rheniums in [Re 12CS 17(CN) 6] n− complexes

The electronic state of carbon in trigonal prismatic environment in [Re 12CS 17(CN) 6] n − complexes with variable redox state n = 6 ↔ 8 was studied by molecular orbital method and electron localization function. The state is characterized by sp 2-hybridisation and oxidation state −4. A weak long-distance interaction between μ 6-С and μ 2-S in the group [(μ 6-С)(μ 2-S) 3] was discovered for n = 6, the interaction disappears for n = 8.

ChemInform Abstract: SrAu4In4 and Sr4Au9In13: Polar Intermetallic Structure with Cations in Augmented Hexagonal Prismatic Environments.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Lanthanide chloride complexes of amine-bis(phenolate) ligands and their reactivity in the ring-opening polymerization of ε-caprolactone

Reaction of two equivalents of n-BuLi with sterically demanding amine-bis(phenol) compounds, H(2)O(2)NN'(R) (Me(2)NCH(2)CH(2)N{CH(2)-3,5-R(2)-C(6)H(2)OH}(2); R = t-Bu or t-Pe (tert-pentyl)) yields isolable lithium complexes, Li(2)(O(2)NN'(R)), in good yields. Upon reaction with one equivalent of LnCl(3)(THF)(x), the lithium salts afford rare earth amine-phenolate chloride complexes in good yields, Ln(O(2)NN'(R))Cl(THF); Ln = Y, Yb, Ho, Gd, Sm, Pr. Crystals of Y(O(2)NN'(t-Bu))Cl(THF), 1, and Sm(O(2)NN'(t-Bu))Cl(DME), 2, suitable for single crystal X-ray crystallographic analysis were obtained. In contrast to previously reported [{Gd(O(2)NN'(t-Pe))(THF)(micro-Cl)}(2)] and related La and Sm complexes, these species are monomeric. 1 contains Y in a distorted octahedral environment bonded to two amine, two phenolate, one THF and one chloride donor. 2 contains Sm in a distorted capped trigonal prismatic environment bonded to two amine, two phenolate, two DME oxygens and one chloride donor. The Ln(O(2)NN'(t-Pe))Cl(THF) complexes were active initators for the controlled ring-opening polymerization of epsilon-caprolactone with a tendency to form low molecular weight cyclic polyesters (M(n) 3000-5000). The conversion rates, although slower than related amido and alkyl species, were different for monomeric and dimeric initiators. The size of the metal centre also affected the conversions and the molecular weights achieved.

Di-μ-methacrylato-bis[diaquabis(methacrylato)europium(III)] methacrylic acid disolvate

In the title centrosymmetric complex, [Eu2(C4H5O2)6(H2O)4]·2C4H6O2, the unique EuIII cation is coordinated by seven carb­oxylate O atoms from four methacrylate ligands and two water mol­ecules in a slightly disorted tricapped trigonal–prismatic environment. Two EuIII ions are bridged by carboxyl­ate groups, forming a dinuclear complex. The formula unit also contains two mol­ecules of methacrylic acid. In the crystal structure, mol­ecules are linked via inter­molecular O—H⋯O hydrogen bonds, forming one-dimensional chains propagating along the b-axis direction

Two novel 1D linear chain alkaline-earth phosphotungstates: Synthesis and crystal structures of M/[α-PW 11O 39] (M = Ca, Sr)

Two novel compounds [(CH 3) 4N] 3.5H 1.5[PW 11O 39Ca(H 2O) 2]·3H 2O 1 and [(CH 3) 4N] 3.5H 1.5[PW 11O 39Sr(H 2O) 2]·1.5H 2O 2 based on lacunary Keggin-type phosphotungstate, have been synthesized by moderate temperature reaction in water and characterized by IR, TG, UV spectra, and X-ray single-crystal diffraction. X-ray single-crystal structural analysis reveals that the adjacent polyanions are polymerized to form a 1D infinitely linear chains by the bridging W O t M(M = Ca, Sr). The Ca(Sr) coordination cations occupy the vacant site of the [α-PW 11O 39] 7− subunit and are heptacoordinate with a distorted monocapped trigonal prismatic environment.

Syntheses, Structures, Magnetism, and Optical Properties of Lutetium-Based Interlanthanide Selenides

Ln3LuSe6 (Ln = La, Ce), beta-LnLuSe3 (Ln = Pr, Nd), and LnxLu4-xSe6 (Ln = Sm, Gd; x = 1.82, 1.87) have been synthesized using a Sb2Se3 flux at 1000 degrees C. Ln3LuSe6 (Ln = La, Ce) adopts the U3ScS6-type three-dimensional structure, which is constructed from two-dimensional 2(infinity)[Ln3Se6](3-) slabs with the gaps between these slabs being filled by octahedrally coordinated Lu(3+) ions. The series of beta-LnLuSe3 (Ln = Pr, Nd) are isotypic with UFeS3. Their structures include layers formed from LuSe6 octahedra that are separated by eight-coordinate Ln(3+) (Ln = Pr, Nd) ions in bicapped trigonal prismatic environments. Sm1.82Lu2.18Se6 and Gd1.87Lu2.13Se6 crystallize in the disordered F-Ln2S3 type structure with the eight-coordinate bicapped trigonal prismatic Ln(1) ions residing in the one-dimensional channels formed by three different double chains via edge- and corner-sharing. These double chains are constructed from Ln(2)Se7 monocapped trigonal prisms, Ln(3)Se6 octahedra, and Ln(4)S6 octahedra, respectively. The magnetic susceptibilities of beta-PrLuSe3 and beta-NdLuSe3 follow the Curie-Weiss law. Sm1.82Lu2.18Se6 shows van Vleck paramagnetism. Magnetic susceptibility measurements show that Gd1.87Lu2.13Se6 undergoes an antiferromagnetic transition around 4 K. Ce3LuSe6 exhibits soft ferromagnetism below 5 K. The optical band gaps for La3LuSe6, Ce3LuSe6, beta-PrLuSe3, beta-NdLuSe3, Sm1.82Lu2.18Se6, and Gd1.87Lu2.13Se6 are 1.26, 1.10, 1.56, 1.61, 1.51, and 1.56 eV, respectively.