Bis[µ-1,3-bis-(1H-imidazol-1-yl)propane-κ(2) N (3):N (3')]bis-(di-chlorido-zinc) dihydrate.

The title hydrated complex, [Zn2Cl4(C9H12N4)2]·2H2O, is a discrete dinuclear zinc complex with 1,3-bis-(1H-imidazol-1-yl)propane as the bridging ligand. The complex mol-ecule lies about a crystallographic inversion centre. The Zn(II) atom exhibits a distorted tetra-hedral coordination geometry defined by two imidazole N atoms and two Cl atoms. O-H⋯Cl hydrogen bonding between the lattice water mol-ecules and the terminal Cl atoms of the mol-ecule lead to a two-dimensional structure extending parallel to (100).

Facile assembly of an unusual lead borate with different cluster building units via a hydrothermal process.

Pb(BO2)2·H2O as sources of B and Pb via a simple hydrothermal process provided the first binodal 5,9-connected lead borate, Pb6B4O11(OH)2 (1). Compound 1 crystallizes in the orthorhombic space group Pnma. The crystal structure is composed of different cluster building units of B4O9 and Pb6O4. Compound 1 has an optical band gap of 3.24 eV.

Poly[[diaqua-tris(µ2-4,4'-bi-pyridine)-bis[µ2-2-(carb-oxylato-methyl-sulfan-yl)nicotinato]dicobalt(II)] 1.3-hydrate].

The title complex, [Co2(C8H5NO4S)2(C10H8N2)3(H2O)2]·1.3H2O, was synthesized under hydro-thermal conditions. The Co(II) ion is six-coordinated in a slightly distorted octa-hedral environment resulting from two carboxyl-ate O atoms of two 2-carb-oxy-methyl-sulfanyl nicotinate (2-CMSN(2-)) anions, one water mol-ecule and three N atoms of three 4,4'-bi-pyridine ligands, with one 4,4'-bi-pyridine ligand situated on a centre of inversion. Two neighboring Co(II) ions are linked by two anions, giving a dinuclear [Co2(2-CMSN)2] subunit with a Co⋯Co separation of 6.8600 (3) Å. The dinuclear subunits are joined by bridging 4,4'-bi-pyridine linkers, generating a three-dimensional network structure. Disordered water mol-ecules are situated in the free space of this network. O-H⋯O hydrogen bonding within and between the subunits enhances the stability of the structure.

Poly[[diaquabis(µ(2)-4,4'-bipyridyl)iron(II)] bis{2-[(3-carboxypyridin-2-yl)disulfanyl]nicotinate}].

In the title compound, {[Fe(C(10)H(8)N(2))(2)(H(2)O)(2)](C(12)H(7)N(2)O(4)S(2))(2)}(n), synthesized by hydro-thermal reaction, the 4,4'-bipyridyl ligands (one with symmetry 2, one with symmetry [Formula: see text]) connect Fe(2+) cations, forming a cationic layer parallel to (001). The coordination of the Fe(2+) cation (site symmetry 2) is octahedral, with four N atoms from four 4,4'-bipyridyl ligands and O atoms from two trans water molecules. Adjacent layers are linked with each other by inter-molecular O-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular structure. Parts of the nicotinic acid derivative are equally disordered over two sets of sites.

Poly[[bis-(2,2-bipyridine)-bis-[µ(6)-5-(carboxyl-atometh-oxy)benzene-1,3-dicarboxyl-ato]trimanganese(II)] monohydrate].

The title compound, {[Mn(3)(C(10)H(5)O(7))(2)(C(10)H(8)N(2))(2)]·H(2)O}(n), was synthesized under hydro-thermal conditions. Six carboxyl-ate groups of six 5-(carboxyl-atometh-oxy)benzene-1,3-dicarboxyl-ate anions (OABDC(3-)) join three Mn(II) ions into a trinuclear centrosymmetric [Mn(3)(µ(2)-COO)(6)] unit with one Mn site situated on a centre of inversion. The latter Mn(II) ion exhibits a distorted MnO(6) coordination, whereas the other Mn(II) ion has a trigonal-bipyramidal MnN(2)O(3) coordination environment resulting from three carboxylate O atoms and the two N atoms of the bipyridine ligand. Adjacent units are linked to each other by OABDC(3-) ligands into a layer parallel to (010). Within the layer, O-H⋯O hydrogen-bonding inter-actions involving the uncoordinated and half-occupied water mol-ecule and the free carboxyl-ate O atoms are observed. The layers stack along [010], constructing a three-dimensional structure through π-π inter-actions between adjacent pyridine rings, with a centroid-centroid distance of 3.473 (5) Å.

catena-Poly[[tetra-aqua-manganese(II)]-µ-5-carboxyl-ato-1-carboxyl-atomethyl-2-oxidopyridinium-κO:O].

In the title coordination polymer, [Mn(C(8)H(5)NO(5))(H(2)O)(4)](n), the Mn(II) atom is coordinated by two carboxyl-ate O atoms from two 5-carboxyl-ato-1-carboxyl-atomethyl-2-oxidopyridinium (L(2-)) ligands and by four water mol-ecules in a distorted octa-hedral geometry. The L(2-) ligands bridge the Mn atoms into an infinite chain motif along [100]; the chains are further inter-linked by O-H⋯O hydrogen bonds into a three-dimensional supra-molecular net.

Penta-aqua-[2-(5-carboxyl-ato-2-oxido-1-pyridinio)acetato]zinc(II) monohydrate.

In the title compound, [Zn(C(8)H(5)NO(5))(H(2)O)(5)]·H(2)O, the Zn(II) atom is coordinated by one O atom from the 2-(5-carboxyl-ato-2-oxidopyridinium-1-yl)acetate ligand and by five water mol-ecules, forming a distorted octa-hedral geometry. Coordinated and uncoordinated water mol-ecules form O-H⋯O hydrogen bonds, leading to a three-dimensional framework.

2-(Carboxy-methyl-sulfan-yl)pyridine-3-carboxylic acid monohydrate.

The title compound, C(8)H(7)NO(4)S·H(2)O, was obtained by reaction of 2-mercaptopyridine-3-carboxylic acid with chloro-acetic acid. In the mol-ecular structure, the dihedral angle between the two least-squares planes defined by the pyridine ring and the carb-oxy group is 8.32 (9)°. The carboxy-methyl-sulfanyl group makes a torsion angle of 82.64 (12)° with the pyridine ring. An intra-molecular O-H⋯N hydrogen bond between the acidic function of the carboxy-methyl-sulfanyl group and the pyridine N atom stabilizes the conformation, whereas inter-molecular O-H⋯O hydrogen bonding with the uncoordinated water mol-ecules is responsible for packing of the structure, leading to chains propagating in [001].

Aqua-[2-(3-carb-oxy-5-carboxyl-atophen-oxy)acetato-κO]bis-(1,10-phenanthroline-κN,N')manganese(II) dihydrate.

In the title complex, [Mn(C(10)H(6)O(7))(C(12)H(8)N(2))(2)(H(2)O)]·2H(2)O, the Mn(II) atom is coordinated by two O atoms from one 2-(3-carb-oxy-5-carboxyl-atophen-oxy)acetate (HOABDC(2-)) dianion and one water mol-ecule and by four N atoms from two 1,10-phenanthroline (phen) ligands within a distorted octa-hedral geometry. O-H⋯O hydrogen bonding between -COOH and -COO(-) groups of adjacent mol-ecules and between carboxyl-ate groups and coordinated and uncoordin-ated water mol-ecules leads to a three-dimensional structure which is further stabilized by weak π-π inter-actions of adjacent phen ligands with centroid-centroid separations of 4.2932 (1) Å.

4,4'-Bipyridine-2-(carb-oxy-methyl-sulfan-yl)pyridine-3-carb-oxy-lic acid (1/1).

In the title co-crystal, C(10)H(8)N(2)·C(8)H(7)NO(4)S, the formate group is coplanar with the pyridyl ring of the acid [dihedral angle = 6.2 (7)°], while the carb-oxy-methyl-sulfanyl group makes a C-S-C-C torsion angle of 70.2 (1)° with the pyridine ring. The dihedral angle between the pyridyl rings of the 4,4'-bipyridine mol-ecule is 27.4 (1)°. The acid and the 4,4'-bipyridine mol-ecules are involved in hydrogen bonding via carb-oxy-lic O and pyridyl N atoms. The structure is further consolidated by inter-molecular C-H⋯O hydrogen bonds, generating a three-dimensional network.

Bis[tetra-aqua-(1,10-phenanthroline-κN,N')cobalt(II)] hexa-aqua-cobalt(II) bis-[3,5-bis-(carboxyl-atometh-oxy)benzoate] tetra-hydrate.

The title compound, [Co(C(12)H(8)N(2))(H(2)O)(4)](2)[Co(H(2)O)(6)](C(11)H(7)O(8))(2)·4H(2)O, was obtanied by the reaction of cobalt acetate with 3,5-bis-(carb-oxy-meth-oxy)benzoic acid and 1,10-phenanthroline. The asymmetric unit contains one tetra-aqua-(1,10-phenanthroline)cobalt(II) cation, one half of a hexa-aqua-cobalt(II) cation that is completed by inversion symmetry, one 3,5-bis-(carboxyl-atometh-oxy)benzoate trianion and two lattice water mol-ecules. The two Co(II) atoms each show a slightly distorted octa-hedral coordination (CoO(6) and CoO(4)N(2)). The cations, anions and lattice water mol-ecules are linked by an intricate network of O-H⋯O hydrogen bonds into a three-dimensional structure.

Study of absorption spectra and (hyper)polarizabilities of SiC(n) and Si(n)C (n=2-6) clusters using density functional response approach.

We theoretically investigate the absorption spectra, dipole polarizabilities, and first-order hyperpolarizabilities of SiC(n) and Si(n)C (n=2-6) clusters using the density functional response approach. Similar to other semiconductor clusters such as Si and gallium arsenide (GaAs) clusters, the absorption spectra of the SiC(n) and Si(n)C clusters show long absorption tails in the low-transition-energy region and strong absorption peaks in the high-transition-energy region (>4.0 eV). For the same n, the absorption spectrum of the Si(n)C cluster is blueshifted with respect to that of the SiC(n) cluster, which may be related to the larger highest occupied molecular orbital-lowest unoccupied molecular orbital gap in the former. The isotropic (alpha) dipole polarizabilities of the SiC(n) and Si(n)C clusters are larger than the bulk polarizability of 3C-SiC and lie between the dipole polarizabilities of Si and C. The SiC(n) clusters have lower dipole polarizabilities and larger first-order hyperpolarizabilities than the Si(n)C clusters. The size dependence of the first-order hyperpolarizabilities of the SiC(n) clusters, which have approximate Si-terminated linear chain geometry, is similar to that observed in pi-conjugated organic molecules.

Bis(µ-5-carboxyl-ato-1-carboxyl-ato-methyl-2-oxidopyridinium)-κO:O;κO:O-[diaqua-(phenan-throline-κN,N')manganese(II)] dihydrate.

The centrosymmetric binuclear title complex, [Mn(2)(C(8)H(5)NO(5))(2)(C(12)H(8)N(2))(2)(H(2)O)(4)]·2H(2)O, was obtained by the reaction of manganese chloride with 5-carb-oxy-1-carboxy-methyl-2-oxidopyridinium and 1,10-phenanthroline. The Mn(II) atom is coordinated by two N atoms from the 1,10-phenanthroline ligand, two O atoms from two 5-carboxyl-ato-1-carboxyl-atomethyl-2-oxidopyridinium ligands and two water mol-ecules, leading to a distorted octahedral MnN(2)O(4) environment. Inter-molecular O-H⋯O hydrogen bonds link neighbouring mol-ecules into a layer structure parallel to (001).

2,2'-(p-Phenyl-enedithio)diacetic acid.

The complete molecule of the title compound, C(10)H(10)O(4)S(2), is generated by a crystallographic inversion centre. In the crystal, mol-ecules are linked into a one-dimensional chain by inter-molecular O-H⋯O hydrogen bonds.

2-[(2-Carboxy-phen-yl)sulfan-yl]acetic acid.

The title compound, C(9)H(8)O(4)S, affords a zigzig chain in the crystal structure by inter-molecular O-H⋯O hydrogen bonds. The molecular geometry suggests that extensive but not uniform π-electron delocalization is present in the benzene ring and extends over the exocyclic C-S and C-C bonds.

Bis(melaminium) tartrate dihydrate.

In the title compound, 2C(3)H(7)N(6) (+)·C(4)H(4)O(6) (2-)·2H(2)O, in which the complete anion is generated by crystallographic twofold symmetry, there are O-H⋯O, N-H⋯O and N-H⋯N hydrogen-bonding inter-actions between neighbouring moieties, forming layers parallel to the bc plane. In addition, π-π contacts [centroid-centroid distance = 3.6541 (9) Å] between the six-membered rings of the melamine cations are observed.

Tetra-aqua-bis(5-hydroxy-nicotinato-κN)cadmium(II).

The title compound, [Cd(C(6)H(4)NO(3))(2)(H(2)O)(4)], was obtained by the reaction of cadmium chloride with 5-hydroxy-nicotinic acid. The Cd(II) atom is located on an inversion centre and is coordinated by two N atoms from two 5-hydroxy-nicotinic acid ligands and four water mol-ecules in a distorted octa-hedral geometry. The structure is stabilized by inter-molecular O-H⋯O hydrogen bonds, forming a three-dimensional network.

Aqua-chlorido{1-[1-(4-hydroxy-phen-yl)-1H-tetra-zol-5-ylsulfan-yl]acetato}(methanol)(1,10-phenanthroline)manganese(II).

The title complex, [Mn(C(9)H(7)N(4)O(3)S)Cl(C(12)H(8)N(2))(CH(4)O)(H(2)O)], contains an Mn(II) ion six-coordinated by one O atom from the 2-[1-(4-hydroxy-phen-yl)-1H-tetra-zol-5-ylsulfan-yl]-acetate ligand, two N atoms from a chelating 1,10-phenanthroline ligand, one O atom from a methanol mol-ecule, one Cl atom and one water mol-ecule in a distorted octa-hedral coordination geometry. The existence of O-H⋯Cl, O-H⋯N and O-H⋯O hydrogen bonds further produces a two-dimensional structure.

3-Hydroxy-adamantane-1-acetic acid.

The crystal structure of the title adamantane derivative, C(12)H(18)O(3), has been determined by X-ray diffraction. The structure is stabilized by inter-molecular O-H⋯O hydrogen bonds, forming a chain.

Dichlorido[3-dimethyl-amino-N-(2-pyridylmethyl-ene)propyl-amine-κN,N',N'']cadmium(II).

In the title mononuclear Cd(II) complex, [CdCl(2)(C(11)H(17)N(3))], the Cd(II) atom is coordinated by two Cl atoms and three N atoms from the tridentate Schiff base ligand in a distorted square-pyramidal environment. The three N atoms and one Cl atom constitute the base of the pyramid, whereas the other Cl atom occupies the apical position.