Bis(2-chloro-,-di-methyl-ethan-1-aminium) tetra-chlorido-cobaltate(II) and tetra-chlorido-zincate(II).

The few examples of structures containing the 2-chloro-,-di-methyl-ethan-1-aminium or 3-chloro-,-di-methyl-propan-1-aminium cations show a compet-ition between and conformations for the chloro-alkyl chain. To explore further the conformational landscape of these cations, and their possible use as mol-ecular switches, the title salts, (CHClN)[CoCl] and (CHClN)[ZnCl], were prepared and structurally characterized. Details of both structures are in close agreement.

5,6-Di-hydro-1,4-dithiine-2,3-di-carb-oxy-lic anhydride.

In the title com-pound (systematic name: 2,3-di-hydro-1,4-dithiino[2,3-]furan-5,7-dione), CHOS, the observed geometry agrees well with those of its phthalamide, thieno and hy-droxy analogs, and with a calculated geometry obtained by density functional theory (DFT) calculations. Specific structural features are an S-C-C-S torsion angle of -70.39 (17)° and S-C bonds to -hybridized C atoms approximately 0.

3-Chloro-,-di-methyl-propan-1-aminium chloride.

The organic cation in the title mol-ecular salt, CHNCl·Cl, exhibits the effect with a C-H bond of the C atom β to the chloro group donating electrons to the anti-bonding orbital of the C-Cl bond to stabilize the conformation [Cl-C-C-C = -68.6 (6)°], as confirmed by DFT geometry optimizations that show a lengthening of the C-Cl bond relative to that of the conformation. Of further inter-est is the higher point group symmetry of the crystal (), compared that of the that of the mol-ecular cation, which arises from a supra-molecular head-to-tail square arrangement of four mol-ecular cations that circulate in a counterclockwise direction when viewed down the tetra-gonal axis.

The square-planar to flattened-tetrahedral CuX4(2-) (X = Cl, Br) structural phase transition in 1,2,6-trimethylpyridinium salts.

The abrupt green-to-yellow thermochromism observed for certain A2CuCl4 compounds has long been attributed to the presence of strong N-H hydrogen bonding in the low-temperature phase that favors square-planar CuCl4(2-) (green in color) through reduction of ligand-ligand repulsion. Weakening of the hydrogen bonding at higher temperature results in the transformation to (far more common) flattened-tetrahedral geometry - the expected geometry for CuBr4(2-) complexes due to their greater ligand-ligand repulsion. The square-planar to flattened-tetrahedral transitions in (1,2,6-trimethylpyridinium)2CuX4 provide the first examples of this phase transformation in the absence of N-H hydrogen bonding and for a CuBr4(2-) complex.

4,4'-(4,5-dimethyl-1,2-phenylene)bis(2-methylbut-3-yn-2-ol): structural variation in vicinal dialkynols.

The structure of the title compound, C(18)H(22)O(2), contains two non-equivalent molecules which differ primarily in the location of the -OH groups on opposite sides or on the same side of the molecular plane. Inversion-symmetric pairs of molecules form intermolecular O-H..

Poly[tetrakis(n-propylammonium) [octa-μ-chlorido-dichloridotrinickelate(II)]]: a hybrid organic-inorganic layer compound in the Cs4Mg3F10 structure type.

The title compound, {(C(3)H(10)N)(4)[Ni(3)Cl(10)]}(n), contains zigzag layers of tri-μ-chlorido-bridged linear 2/m-symmetric Ni(3)Cl(12) segments, linked by mono-μ-chlorido quasi-linear bridges to two other segments at each end. These inorganic layers are interleaved with interdigitated bilayers of mirror-symmetric n-propylammonium cations, the ammonium head groups of which are directed into the inorganic layers to form multiple N-H···Cl hydrogen bonds, while the propyl tail groups pack together in a tongue-and-groove manner in the center of the bilayer. The propyl groups are ordered at 100 K but disordered with opposite conformations on the mirror plane at 240 K.

Bis(1-methyl-piperidinium) tetra-chlorido-cuprate(II).

The structure of the title compound, (C(6)H(14)N)(2)[CuCl(4)], consists of two inequivalent 1-methyl-piperidinium cations and a flattened tetra-hedral [CuCl(4)](2-) anion. Each organic cation exhibits a chair conformation with the methyl group in the equatorial position. They are segregated into alternating layers parallel to (100) and stacked along [100].

[CuCl3(H2O)](-) complexes aggregated to form hydrate columns in methyl-substituted pyridinium or piperidinium salts.

1,2,3-Trimethylpyridinium aquatrichloridocuprate(II), (C(8)H(12)N)[CuCl(3)(H(2)O)], (I), 3,4-dimethylpyridinium aquatrichloridocuprate(II), (C(7)H(10)N)[CuCl(3)(H(2)O)], (II), and 2,3-dimethylpyridinium aquatrichloridocuprate(II), (C(7)H(10)N)[CuCl(3)(H(2)O)], (III), exhibit the same fundamental structure, with (I) and (II) isomorphous and with the unit-cell constants of (III) similar to the reduced unit-cell constants of (I) and (II). The distorted square-planar [CuCl(3)(H(2)O)](-) complex [mirror symmetric in (I) and (II)] forms two semicoordinate Cu···Cl bonds to a neighboring complex to produce a dimer with 2/m symmetry [only inversion symmetry in (III)]. The semicoordinate Cu.

Nine compounds containing high-nuclearity [Cu(n)X(2n+2)]2- (n = 4, 5 or 7; X = Cl or Br) quasi-planar oligomers.

The structures of seven A(2)Cu(4)X(10) compounds containing quasi-planar oligomers are reported: bis(1,2,4-trimethylpyridinium) hexa-μ-chlorido-tetrachloridotetracuprate(II), (C(8)H(12)N)(2)[Cu(4)Cl(10)], (I), and the hexa-μ-bromido-tetrabromidotetracuprate(II) salts of 1,2,4-trimethylpyridinium, (C(8)H(12)N)(2)[Cu(4)Br(10)], (II), 3,4-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (III), 2,3-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (IV), 1-methylpyridinium, (C(6)H(8)N)(2)[Cu(4)Br(10)], (V), trimethylphenylammonium, (C(9)H(14)N)(2)[Cu(4)Br(10)], (VI), and 2,4-dimethylpyridinium, (C(7)H(10)N)(2)[Cu(4)Br(10)], (VII). The first four are isomorphous and contain stacks of tetracopper oligomers aggregated through semicoordinate Cu···X bond formation in a 4(5/2,1/2) stacking pattern. The 1-methylpyridinium salt also contains oligomers stacked in a 4(5/2,1/2) pattern, but is isomorphous with the known chloride analog instead.

catena-Poly[bis(trimethylphenylammonium) [hexa-mu-chlorido-dichloridotricuprate(II)]]: an alternating zigzag chain of CuCl(4) and Cu(2)Cl(6) complexes.

The title compound, {(C(9)H(14)N)(2)[Cu(3)Cl(8)]}(n), consists of parallel chains of alternating quasiplanar Cu(2)Cl(6) and planar CuCl(4) complexes separated by trimethylphenylammonium cations. Both inorganic complexes possess inversion symmetry. Pairs of neighboring chloride ions of the CuCl(4) complex each form a symmetric bridge and an asymmetric bridge to Cu(2)Cl(6) complexes on either side.

Octakis(dimethylammonium) hexa-mu2-chlorido-hexachloridotrinickelate(II) dichloride: a linear trinickel complex with asymmetric bridging.

The title compound, (C2H8N)8[Ni3Cl12]Cl2, crystallizes as linear [Ni3Cl12]6- complex anions with inversion symmetry, separated from one another by dimethylammonium cations and noncoordinated chloride ions. The gross structural arrangement of the trinickel complex is as a segment of face-sharing NiCl6 octahedra similar to the (NiCl3)n chains of CsNiCl3-type compounds. On closer inspection, the regular coordination geometry of the complex consists of octahedral NiCl6 in the center linked by two symmetrically bridging chloride ions to square-pyramidal NiCl5 on each end.

Bis(1,3,4-trimethylpyridinium) tetrachloridocuprate(II) and bis(1,3,4-trimethylpyridinium) tetrabromidocuprate(II): an examination of the A2CuX4 Fdd2 structure type.

The title bis(1,3,4-trimethylpyridinium) tetrahalidocuprate(II) structures, (C8H12N)2[CuCl4], (I), and (C8H12N)2[CuBr4], (II), respectively, consist of flattened [CuX4]2- tetrahedral complex anions and planar 1,3,4-trimethylpyridinium cations. Chloride compound (I) is a rare example of an A2CuCl4 structure with an elongated unit cell in the polar space group Fdd2. The [CuCl4]2- anions have twofold rotational symmetry and are arranged in distorted hexagonal close-packed (hcp) layers, which are interleaved with layers of cations, each in a four-layer repeat sequence, to generate the elongated axis.

1,2-Diiodo-4,5-dimethyl-benzene.

The structure of the title compound, C(8)H(8)I(2), conforms closely to the mm2 symmetry expected for the free mol-ecule and is the first reported structure of a diiodo-dimethyl-benzene. Repulsion by neighboring I atoms and the neighboring methyl groups opposite to them results in a slight elongation of the mol-ecule along the approximate twofold rotation axis that bis-ects the ring between the two I atoms. In the extended structure, the mol-ecules form inversion-related pairs which are organized in approximately hexa-gonal close-packed layers and the layers then stacked so that mol-ecules in neighboring layers abut head-to-tail in a manner that optimizes dipole-dipole inter-actions.

1-Ethyl 2,2-dimethyl 3-(1,3-benzodioxol-5-yl)propane-1,2,2-tricarboxylate.

The molecular structure of the title triester compound, C(17)H(20)O(8), consists of a benzodioxole fused-ring system, an ethoxycarbonylmethyl group and two methoxycarbonyl groups arranged around a tetrahedral carbon center. Unlike similar triesters, which are oils, the title compound crystallizes at room temperature as interdigitated bilayers of triester molecules, with short O..

(1E)-2-(Diacetylamino)-1-methylprop-1-enyl acetate.

The analysis of the title compound, C10H15NO4, firmly establishes the configuration of the double bond as E, a stereochemistry that had been assigned tentatively by other methods. The diacetylamine and acetate substituents are approximately coplanar to one another, but approximately perpendicular to the planar ethene core. H atoms of the ethene methyl substituents are found within the ethene plane, indicating that hyperconjugation does not play an important role in stabilizing the double bond.

Vanadium Hydrotris(pyrazolyl)borate Complexes of Diphenyl Phosphate. Heterometallic Complexes of the [LV{(PhO)(2)PO(2)}(3)](-) Fragment.

The synthesis and characterization of nine trinuclear, mixed metal complexes of the type [LV{&mgr;-(PhO)(2)PO(2)}(3)](2)M, where the vanadium is in the 3+ oxidation state, L = hydrotris(pyrazolyl)borate, and M = Ba(II) (1), Ca(II) (2), Mg(II) (3), Mn(II) (4), Co(II) (5), Ni(II) (6), Fe(II) (7), 2 Na(I) (8), Al(III) (9), and La(III) (10), are described. X-ray crystal structural analysis of 1, 3, and 4 gave the following parameters: 1, C(92)H(84)B(2)N(12)O(24)P(6)Cl(4)BaV(2), C2/c, a = 26.730(5) Å, b = 15.

Non-Template-Centered, Closed Tetravanadium Phosphate and Phosphonate Clusters.

Tetranuclear V(III) complexes, [HB(pz)(3)](4)V(4)(&mgr;-C(6)H(5)OPO(3))(4) (I), its acetonitrile solvate (I.4CH(3)CN), and [HB(pz)(3)](4)V(4)(&mgr;-O(2)NC(6)H(4)OPO(3))(4).4C(7)H(8).