Paralavas in the Cretaceous Paraná volcanic province, Brazil - A genetic interpretation of the volcanic rocks containing phenocrysts and glass.

The occurrences of glassy rocks containing long and curved phenocrysts in the Paraná volcanic province, South America, are here interpreted as paralavas. The large number of thin (0.1-0.5 m) dikes and sills of glassy volcanic rocks with hopper, hollow or curved, large crystals of clinopyroxene (up to 10 cm), plagioclase (up to 1 cm), magnetite and apatite are contained in the core of thick (>70 m) pahoehoe flows. They are strongly concentrated in the state of Paraná, coincident with the presence of the large number of dikes in the Ponta Grossa arch. These rocks were previously defined as pegmatites, although other names have also been used. A paralava is here interpreted as the product of melting of basaltic rocks following varied, successive processes of sill emplacement in high-kerogen bituminous shale and ascent of the resultant methane. As the gas reached the lower portion of the most recent lava flow of the volcanic pile, the methane reacted with the silicate and oxide minerals of the host volcanic rock (1,000 ºC) and thus elevated the local temperature to 1,600 ºC. The affected area of host rock remelted (possibly 75 wt.%) and injected buoyantly the central and upper portion of the core. This methane-related mechanism explains the evidence found in the paralavas from this volcanic province, one of the largest in the continents.

An anisaldehyde sodium bisulfite derivative: poly[[µ4-(hydroxy)(4-methoxyphenyl)methanesulfonato]sodium].

The title complex, [Na(C(8)H(9)O(5)S)](n), is polymeric and consists of broad layers parallel to (100) made up of an inner hydrophilic core of Na(+) cations and polar SO(3)C(OH)- groups, padded on both sides by two hydrophobic layers of pendant methoxyphenyl groups. The Na(+) cations in the inner core are six-coordinated into highly distorted NaO(6) octahedra by four symmetry-related (hydroxy)(4-methoxyphenyl)methanesulfonate anions, leading to a tightly woven two-dimensional structure. While there are some hydrogen bonds providing interplanar cohesion, interactions between adjacent layers are weak hydrophobic ones. The present compound appears to be the first reported structure containing the (hydroxy)(4-methoxyphenyl)methanesulfonate ligand.

An unusual two-dimensional hydrogen-bonding network in bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) peroxodisulfate dihydrate.

The title compound, 2C(14)H(13)N(2)(+).S(2)O(8)(2-).2H(2)O, is a protonated amine salt which is formed from two rather uncommon ionic species, namely a peroxodisulfate (pds(2-)) anion, which lies across a crystallographic inversion centre, and a 2,9-dimethyl-1,10-phenanthrolin-1-ium (Hdmph(+)) cation lying in a general position. Each pds(2-) anion binds to two water molecules through strong water-peroxo O-H...O interactions, giving rise to an unprecedented planar network of hydrogen-bonded macrocycles which run parallel to (100). The atoms of the large R(8)(8)(30) rings are provided by four water molecules bridging in fully extended form (...H-O-H...) and four pds(2-) anions alternately acting as long (...O-S-O-O-S-O...) and short (...O-S-O...) bridges. The Hdmph(+) cations, in turn, bind to these units through hydrogen bonds involving their protonated N atoms. In addition, the crystal structure also contains pi-pi and aromatic-peroxo C-H...O interactions.

Cadmium sulfite hexahydrate revisited.

The present structural revision of the title compound, tetra-cadmium tetra-sulfite hexa-hydrate, [Cd(4)(SO(3))(4)(H(2)O)(5)]·H(2)O, is a low-temperature upgrade (T = 100 K and R = 0.017) of the original room-temperature structure reported by Kiers & Vos [Cryst. Struct. Commun. (1978). 7, 399-403; T = 293 K and R = 0.080). The compound is a three-dimensional polymer with four independent cadmium centres, four sulfite anions and six water mol-ecules, five of them coordinated to two cadmium centres and the remaining one an unbound solvent mol-ecule which completes the asymmetric unit. There are two types of cadmium environment: CdO(8) (through four chelating sulfite ligands) and CdO(6) (by way of six monocoordinated ligands). The former groups form planar arrays [parallel to (001) and separated by half a unit cell translation along c], made up of chains running along [110] and [10], respectively. These chains are, in turn, inter-connected both in an intra-planar as well as in an inter-planar fashion by the latter CdO(6) polyhedra into a tight three-dimensional framework. There is, in addition, an extensive network of hydrogen bonds, in which all 12 water H atoms act as donors and eight O atoms from all four sulfite groups and two water mol-ecules act as acceptors.

Di-µ-acetato-κO,O':O;κO:O,O'-bis-[(acetato-κO,O')(1,10-phenan-throline-κN,N')cadmium(II)].

The title compound, [Cd(2)(C(2)H(3)O(2))(4)(C(12)H(8)N(2))(2)], consists of dimeric units built up around a crystallographic symmetry centre. Each cadmium(II) unit is chelated by a 1,10-phenanthroline (phen) group and two acetate ligands, one of which also acts as a bridge, linking both seven-coordinated cadmium(II) centres. The crystal structure is governed by a single π-π inter-action between stacked phen groups [centroid-centroid distance 3.5209 (11) Å], leading to a planar structure parallel to (010).

Disodium zinc bis-(sulfate) tetra-hydrate (zinc astrakanite) revisited.

We present a new low-temperature refinement of disodium zinc bis-(sulfate) tetra-hydrate {systematic name: poly[tetra-µ-aqua-di-µ-sulfato-zinc(II)disodium(I)]}, [Na(2)Zn(SO(4))(2)(H(2)O)(4)](n) or Zn astrakanite, which is an upgrade of previously reported data [Bukin & Nozik (1974 ▶). Zh. Strukt. Khim.15, 712-716]. The compound is part of an isostructural family containing the Mg (the original astrakanite mineral), Co and Ni species. The very regular ZnO(aqua)(4)O(sulfate)(2) octa-hedra lie on centres of symmetry, while the rather distorted NaO(aqua)(2)O(sulfate)(4) octa-hedra appear at general positions, linked into a three-dimensional network by the bridging water mol-ecules and the fully coordinated sulfate groups.

An unusual P3 1 2 framework for the Ni(4,4'-bipyridine)(H2O)4 chain.

catena-Poly[[[tetraaquanickel(II)]-mu-4,4'-bipyridine-kappa(2)N:N'] thiosulfate dihydrate], {[Ni(C(10)H(8)N(2))(H(2)O)(4)]S(2)O(3).2H(2)O}(n), (I), and catena-poly[[[tetraaquanickel(II)]-mu-4,4'-bipyridine-kappa(2)N:N'] sulfate methanol solvate monohydrate], {[Ni(C(10)H(8)N(2))(H(2)O)(4)]SO(4).CH(4)O.H(2)O}(n), (II), are built up of {[Ni(4,4'-bipy)(H(2)O)(4)](2+)}(n) chains (4,4'-bipy is 4,4'-bipyridine) interwoven in an unusual P3(1) fashion. Voids are filled by the corresponding counter-anions and solvate molecules, defining a complex three-dimensional network surrounding them. In both structures, the cationic chains evolve around a set of twofold axes passing through the Ni(II) ions and bisecting the aromatic amines through their N (and their opposite C) atoms.

Poly[[mu2-4,4'-bipyridine-di-mu3-sulfito-dizinc(II)] monohydrate].

The title compound, {[Zn(2)(SO(3))(2)(C(10)H(8)N(2))].H(2)O}(n), is a two-dimensional polymer built up of a [ZnSO(3)](n) chain evolving around a 2(1) axis and interconnected by a 4,4'-bipyridine spacer. The resulting two-dimensional structures are linked, in turn, by hydrogen bonding mediated by the solvent water molecule. The organic ligand lies on a centre of symmetry located on the mid-point of the bond between the rings, while the solvent water molecule is halved by a twofold axis passing through the O atom.

A polymeric zinc thiosulfate complex containing anionic and cationic chains based on tetrahedral and octahedral zinc sites.

catena-Poly[[[tetraaquazinc(II)]-mu-4,4'-bipyridine-kappa(2)N:N'] [[mu-thiosulfato-kappa(2)O:S-bis[(thiosulfato-kappaS)zinc(II)]]-di-mu-4,4'-pyridine-kappa(4)N:N'] dihydrate], {[Zn(C(10)H(8)N(2))(H(2)O)(4)][Zn(2)(S(2)O(3))(3)(C(10)H(8)N(2))(2)].2H(2)O}(n), is a polymeric zinc complex built up from thiosulfate-containing anionic chains, where the Zn atom is tetrahedrally coordinated, and aqua-containing cationic chains incorporating octahedrally coordinated Zn. In each type of chain, the 4,4'-bipyridine units act as spacers, and the chains run along three non-intersecting almost orthogonal directions in space. The profusion of hydrogen-bond donors (all the H atoms of the water molecules) and acceptors (the thiosulfate O and S atoms) generates a very complex hydrogen-bonding scheme.

A new simplifying approach to molecular geometry description: the vectorial bond-valence model.

A method to describe, analyze and even predict the coordination geometries of metal complexes is proposed, based on previous well established concepts such as bond valence and valence-shell electron-pair repulsion (VSEPR). The idea behind the method is the generalization of the scalar bond-valence concept into a vector quantity, the bond-valence vector (BVV), with the innovation that the multidentate ligands are represented by their resultant BVVs. Complex n-ligand coordination spheres (frequently indescribable at the atomic level) reduce to much simpler ones when analyzed in BVV space, with the bonus of a better applicability of the VSEPR predictions. The geometrical implications of the BVV description are analyzed for the cases of n=2 and 3 (n=number of ligands), and the validity of its predictions, checked for a large number of metal complexes.

Aqua(thiosulfato-kappa2O,S)[2,4,6-tri-2-pyridyl-1,3,5-triazine-kappa3N2,N1,N6]zinc(II) hemihydrate.

The title compound, [Zn(S2O3)(C18H12N6)(H2O)].0.5H2O, contains two almost identical independent monomeric moieties composed of an octahedral Zn centre coordinated by a tridentate 2,4,6-tri-2-pyridyl-1,3,5-triazine (tpt) ligand, one aqua ligand and an O,S-chelating thiosulfate anion. The structure is stabilized by a solvent water molecule. Multiple strong hydrogen bonds with additional weaker pi-pi interactions between tpt groups define a multiple column spatial organization.

Triaquamanganese sulfite revisited.

Orthorhombic Mn(SO3)(H2O)3 has been reinvestigated by single-crystal X-ray diffraction in two possible space groups, viz. P2(1)2(1)2(1) (with all atoms in general positions) and Pnma (with the molecule bisected by a mirror plane). The results confirm the lower symmetry assigned in a previous single-crystal neutron diffraction study. However, the refinement of the P2(1)2(1)2(1) model requires the introduction of racemic twinning and soft positional and displacement restraints for the H atoms. The importance of a scrupulous report on symmetry absence violations as standard policy in crystallographic work is discussed.

Di-mu2-sulfito-kappa8O,O':O',O''-bis[(2,4,6-tri-2-pyridyl-1,3,5-triazine-kappa3N2,N1,N6)cadmium(II)] octahydrate.

The title compound, [Cd2(SO3)2(C18H12N6)2].8H2O, is a dimer built up around a symmetry center, where the sulfite anion displays a so far unreported coordination mode in metal-organic complexes; the anion binds as a mu2-sulfite-kappa4O,O':O',O'' ligand to two symmetry-related seven-coordinate Cd(II) cations, binding through its three O atoms by way of two chelate bites with an O atom in common, which acts as a bridge. The cation coordination is completed by a 2,4,6-tri-2-pyridyl-1,3,5-triazine ligand acting in its usual tridentate mode.

Bis[(acetato-kappa(2)O,O')bis(4,4'-dimethyl-2,2'-bipyridyl-kappa(2)N,N')zinc(II)] trithionate pentahydrate.

The title ionic zinc-acetate complex, [Zn(C2H3O2)(C12H12N2)2]2(S3O6).5H2O, contains a ZnN4O2 nucleus provided by the three bidentate ligands acting in a chelating mode. The trithionate unit, in turn, acts as an isolated charge-balancing counter-ion. The structure has a three-dimensional assembly achieved through three different interaction types, viz. Coulomb, hydrogen bonding and pi-pi. The trithionate group and one of the solvent water molecules are disordered around inversion centers.

Two Cd and Hg peroxodisulfate complexes with aromatic amines.

The crystal structures of two complexes containing the peroxodisulfate anion are reported, namely mu-peroxodisulfato-1kappaO:2kappaO'-bis[(acetato-kappa2O,O')aqua(2,2':6',2''-terpyridine-kappa3N,N',N'')cadmium(II)] heptahydrate, [Cd2(C2H3O2)2(S2O8)(C15H11N2)2(H2O)2].7H2O, (I), and catena-poly[[[bis(2,2'-bipyridine-kappa2N,N')mercury(II)]-mu-peroxodisulfato-kappa2O:O'] 0.4-hydrate], {[Hg(C10H8N2)2(S2O8)].0.4H2O}n, (II). In both structures, the anion behaves as a bridge, linking neighbouring coordination polyhedra in two different ways, either tightly bound to the heptacoordinated Cd2+ cation forming neatly separated dimeric entities in (I) or across a shorter O-S-O path producing weakly connected chains by way of 'semicoordination' to the Hg2+ cations in (II).

Di-mu-sulfito-bis[(4,4'-dimethyl-2,2'-bipyridine)zinc(II)] dihydrate and poly[[aqua(1,10-phenanthroline)zinc(II)]-mu3-sulfito-zinc(II)-mu3-sulfito].

Two different zinc sulfite compounds have been prepared through the decomposition of pyrosulfite-dithionite ions in aqueous solution, viz. a dimeric complex, di-mu-sulfito-kappa3O,O':O'';kappa3O:O',O''-bis[(4,4'-dimethyl-2,2'-bipyridine-kappa2N,N')zinc(II)] dihydrate, [Zn2(SO3)2(C12H12N2)2].2H2O, (I), which was solved and refined from a twinned sample, and an extended polymer, poly[[aqua(1,10-phenanthroline-kappa2N,N')zinc(II)]-mu3-sulfito-kappa2O:O':O''-zinc(II)-mu3-sulfito-kappa3O:O:O'], [Zn2(SO3)2)(C12H10N2)(H2O)]n, (II). In (I), the dinuclear Zn(II) complex has a center of symmetry. The cation is five-coordinate in a square-pyramidal arrangement, the anion fulfilling a bridging chelating role. Compound (II) comprises two different zinc units, one being five-coordinate (square pyramidal) and the other four-coordinate (trigonal pyramidal), and two independent sulfite groups with different binding modes to the cationic centers.

catena-poly[[aqua(3,4,7,8-tetramethyl-1,10-phenanthroline-kappa2N,N')cadmium(II)]-mu3-thiosulfato-kappa3S:S:O].

The title compound, [Cd(S(2)O(3))(C(16)H(16)N(2))(H(2)O)](n), presents a polymeric one-dimensional structure running along the P2(1)/c glide direction, with elementary units defined by six-coordinate Cd(II) atoms bonded to three symmetry-related thiosulfate groups, a bidentate tetramethylphenanthroline ligand and one aqua ligand. The bridging thiosulfates bind metal centers through two different sequences, viz. Cd-S-Cd' and Cd'-S'-S'-O'-Cd, defining a closed six-membered ring. Individual chains are held together via pi-pi interactions to generate two-dimensional networks parallel to the (100) plane. These, in turn, are connected by much weaker van der Waals interactions.

A novel five-coordinate cadmium phenanthroline thiosulfate.

The structure of the novel cadmium phenanthroline thiosulfate poly[[(1,10-phenanthroline-kappa(2)N,N')cadmium(II)]-micro(3)-thiosulfato-kappa(3)S:S:O], [Cd(S(2)O(3))(C(12)H(8)N(2))](n), with a pentacoordinated Cd centre, is reported. It forms linear chains built up around a 2(1) axis and is isostructural with the known bipyridine homologue. The structure is also compared with a previously reported closely related monoaqua monohydrated phase, where the Cd(2+) cation is hexacoordinated. The incidence of weak C-H.O interactions in the determination of its general packing properties is discussed.

Two new dimeric cadmium(II) and zinc(II) sulfate complexes with 2,4,6-tris(2-pyridyl)-1,3,5-triazine and 2,2:6',2"-terpyridine.

The structures of two new sulfate complexes are reported, namely di-mu-sulfato-kappa(3)O,O':O"-bis(aqua[2,4,6-tris(2-pyridyl)-1,3,5-triazine-kappa(3)N(1),N(2),N(6)]cadmium(II)) tetrahydrate, [Cd(2)(SO(4))(2)(C(16)H(12)N(6))(2)(H(2)O)(2)].4H(2)O, and di-mu-sulfato-kappa(2)O:O'-bis[(2,2':6',2"-terpyridine-kappa(3)N(1),N(1'),N(1"))zinc(II)] dihydrate, [Cd(2)(SO(4))(2)(C(15)H(11)N(3))(2)].2H(2)O, the former being the first report of a Cd(tpt) complex [tpt is 2,4,6-tris(2-pyridyl)-1,3,5-triazine]. Both compounds crystallize in the space group P-1 and form centrosymmetric dimeric structures. In the cadmium complex, the metal center is heptacoordinated in the form of a pentagonal bipyramid, while in the zinc complex, the metal ion is in a fivefold environment, the coordination geometry being intermediate between square pyramidal and trigonal bipyramidal. Packing of the dimers leads to the formation of planar structures strongly linked by hydrogen bonding.

Two hydrates of 2,6-bis(1H-benzimidazol-2-yl)pyridine.

The structures of the mono- and sesquihydrates of 2,6-bis(1H-benzimidazol-2-yl)pyridine (bbip) are reported. Phase (I), C(19)H(13)N(5).H(2)O, has one water and one bbip molecule in the asymmetric unit, while phase (II), C(19)H(13)N(5).1.5H(2)O, has three water molecules and two bbip molecules in the asymmetric unit. The compounds exhibit very similar molecular geometries but different packing organizations, which result from intricate hydrogen-bonding schemes.