Thl.: Ri elwc ld mc thod ofstructurl.: refinement
from powder dilTr<:lction patterns is widely used with neutron
data and int:reasingly so with x* ray data . [n this p<:lper the
Ril.:tveld method has hccn cxplainl.:d. As an ex.ample the
t: rystal :-.truclure of LazCu04 at rollm It:mperaturc has been
refined using x*ray powder dirfr<:lctiol1 data. The crystal
,lruc lure is llflhorombi c wilh a = 5.154S(4)A .
h = 5.411116(1)A . c = 13.1529 (9)A. and space gfllUp em,"'
A sample of La2Cu04 has been oxidized to La2Cu04+0 and
its magnetic susceptibily as a function or temperature has
heen studied. The new m(ltcrial is supcrconductor with
Tc == 30K. Further investigation is in progress to determine
the va lue or () and the position of the extra oxygen atOl11s in
tht..: cell.

Single crystals of CdTe were grown by the
sublimation and condensation technique in a silica, under an
argon gas now, and also by alloing cadmium tcJloride
transport within an evacuated silica ampoule. X-ray powder
diffraction patlerns prepared from each group of grown
crys tals showed the crystal structure of the examined
samples to be zinc-blend race-cent red cubic. Transmission
electron microscopy of CdTe single crysta ls confirm the
cryst:il structu re to be face-centred cubic with a = 6.5(3) A.
and space group F 43m.
 

A software in fortran is developed to determine
crystal structure of cubic. tetragonal. hexago nal and
orthorhombic crystals from powder ditTraction d values. The
general 1t6s method is also used for triclinic and monoclinic
crystals.

The Crystal Structure of I benzyll Silane (CH3h Si CH (C(> H ~ )CH2 COC(>Hs has been
determined by direct method (Sir). The dimensions of used
cry:,tal were 0.7 x 0.3 x 0.2 mm. TIle molecular structure has
been determined by MolEN program. This compound
crystalizc.s in monoclinic space group P2t /n (14) with four
molecules per unit cell. Lattice parameters of this
compound an.:: :
a = 6.0938 A. h = 22.8465 A. c = 12.0533 A. p= 92.0605'
Afll.::r lasl least· square cycle, lht.! final R anJ R.,... values are
0.087 and 0.093 , re.spectively.

Single crystals of binary semiconducto r CdSe
were grown by subJimalion and conde nsation techniques
wing ca rrier argon gas. Powder X-ray diffraction as well as
Transmission e lectron microscopy o f powde red crystals
confiml Ihe cryslal st ructure to be hexagonal with :
a = 4.299 A, c = 7.010 A and space grope P6,MC

The reaction between LH₂, [pyda.H₂][pydc], ( pyda = 2,6 –pyridinediamine and pydc. H₂ = 2,6 – pyridinedicarboxylic acid),  ligand with palladium(II) chloride leads to the formation of [pyda.H]₂[PdCl₄]. The crystal structure of the compound was determined by X–ray diffraction. The crystal system is triclinic with space group Pī and one molecule per unit cell. The unit cell dimensions are a = 6.900(3) Å, b  = 7.898(3) Å, c = 8.025 (3) Å, with α = 103.302(14)º, β  = 104.068(14)º and γ = 92.415(12)º. The final R value is 0.0602 for 1988 reflections. The presumably of the formation [pyda.H][Pd(pydc)(pydc.H)], [Pd(pydc.H)₂] and [pyda.H]Cl species, was studied by IR, ESI/MS, ¹H NMR, ¹³C NMR spectroscopy, and elemental analysis.

In this research N(2-chloro-phenyl)4-nitro-thiobenzamide as a ligand was synthesized. One mmol of mercury oxide was added to the solution of 1 mmol ligand in 45 ml chloroform and after 90 min the mixture through celite or BaS to remove unreacted mercury(II) compounds. The yellow crystals, which formed by slow evaporization, was separated and recrystallized from chloroform as fine yellow crystals with 87% yield and dried in vacuo. The crystal structure of above complex was determined by single crystal X-ray diffraction method. The complex crystals in a monoclinic unit cell with a = 8.2822(9) Å, b = 12.2907(9) Å,  c = 13.1243(13) Å, α = 90°, β = 98.729(5)°, γ = 90° and Z = 2 and space group P21/c. The S-Hg-S is linear with angle of 180º.

The reaction of gallium (III) nitrate octahydrate with the proton transfer compound (pydaH₂)²⁺ (pydc)^2– ( where  pyda  is 2,6-pyridinediamine and pydcH₂ is 2,6-pyridinedicarboxylic acid) leads to the formation of (C₅H₈N₃) [Ga(C₇H₃NO₄)₂] · 4H₂O · CH₃OH. The crystal system of the anionic complex is triclinic with space group Pī and two molecules per unit cell. The unit cell parameters are a=10.238(2) Å, b=10.428(2) Å, c=13.838(2) Å, α=70.375(3)°, β=77.938(3)°, γ=64.120(3)°. The structure has been refined to a final value for the crystallographic R factor of 0.0579 based on 4703 reflections with I > 2σ(I).

The Dinuclear Cu (II) complex [{CuCl}₂(μ – tppz)](PF₆)₂, where tppz represents tetra-2-pyridinylpyrazine, has been prepared and characterized by elemental analysis, ¹H-NMR, IR and UV-vis spectroscopies. A crystal structure of the complex showed the Cu (II) are surrounded by three N atoms of tppz bridging ligand and one Cl atom. Crystal structure data are as follows: crystal system monoclinic, space group C2/m, a= 13.314(3), b= 12.901(2), c= 8.9039(17) Å, β= 99.260º, V=1509.4(5) ų and Z=2. The structure was refined to a final R factor of 0.0416. The crystal structure revealed that the Cu(II) are respectively above and below the plane of the pyrazine moiety of the bridging tppz ligand with the pyridine moieties moving out of the pyrazine plane in order to coordinate to Cu(II). Each chloride ligand bonds equatorially to Cu(II) in a [{CuCl}₂(m-tppz)]²⁺ ion and axially to a neighboring [{CuCl}₂(m-tppz)]²⁺ ion so as to form a one-dimensional chain in the solid state.

CdS thin films were deposited by thermal evaporation in a vacuum of ~ 10^-5 torr at room temperature. Samples were subjected to annealing in the range of temperatures 100-300 ^oC for 1 hour in air.The crystal structure of CdS films was characterized by XRD technique. Only hexagonal phase with the preferred (002) plane was found in CdS films

Thin films Indium tin oxide (ITO) with various thicknesses, from 130-620nm, have been deposited on the thin glass substrates by RF sputtering using ITO ceramic (90% wt. In₂O₃ and 10% wt. SnO₂) target, and subsequently annealed in vacuum at various temperatures. Electrical and optical characteristics of ITO samples, before and after annealing at different temperatures, were investigated by four point probe and UV/VIS/IR spectrophotometer. Structural properties of layers deposited at optimum temperature of 400˚C were analyzed by XRD. SEM analysis was used to investigate the morphology of the optimal surface layer. Results show that by increasing the thickness, crystalline structure varies, so that sheet resistance, resistivity and transparency of films vary. Layer deposited with 130nm (lower thickness) has 83.71% transmittance and 2.34×10^-4Ωcm resistivity. In contrast, 620nm thickness film with 79.07% transparency has the lowest electrical resistivity about 1×10^-4Ωcm at 400˚C. This layer can be used as an optimal film with 1.6 Ω/□ sheet resistance for many applications.    

The reaction of copper (II) nitrate with pyridine-2,6-dicarboxylic acid, (pydcH₂) and 2,2'-bipyridine (2,2'-bipy) led to the formation of the title compound, [Cu(C₇H₄NO₄)(C₁₀H₈N₂)(H₂O)]NO₃.H₂O, or [Cu(pydcH)(2,2'-bipy)(H₂O)]NO₃.H₂O. The crystal system of the complex is triclinic with space group P and two molecules per unit cell. The unit cell parameters are: a = 7.0438 (6) Å, b = 11.3215 (10) Å, c = 12.9148 (9) Å, α = 107.498 (4)°, β = 94.557 (5)° and  g = 104.325 (5)°. The final R value was 0.03 for 3601 observed reflections. The cationic complex features six-coordinate Cu^II with a distorted octahedral geometry with a significantly longer Cu1—O4 bond [2.5491(16) Å]. Considerable C═O···π stacking interactions between the C═O groups with distance of 3.498 (2) Å are observed. In addition, distinct intermolecular O—H···O and N—H···O hydrogen bonds lead to the formation of R(12) and C(12) graph sets motifs. In the crystal structure, a wide range of non-covalent interactions consisting of hydrogen bonding (O—H···O, O—H···N and C—H···O), π–π [centroid–centroid distances of 3.5193 (13) Å and 3.6876 (13) Å] and C═O···π stacking interactions connect the various components into a supramolecular structure.

New Schiff-base compounds N-(3,4-dimethoxybenzylidene)-4-methoxyaniline (1) and N-(3,4-dimethoxybenzylidene)-4-ethoxyaniline (2) were synthesized and characterized by elemental analyses (CHN) and FT-IR spectroscopic techniques. Crystal structures of 1 and 2 were obtained by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic, space group P2₁ with two independent molecules (A and B), with unit cell parameters: a = 14.8198(4), b = 7.1656(2), c = 13.2982(4) Ǻ, β = 103.289(2)°, V = 1374.36(7) Ǻ³ and Z = 4 and compound 2 crystallizes in the monoclinic space group P2₁/n with unit cell parameters: a = 16.5638(6), b = 7.3546(2), c = 12.7449(4) Ǻ, β = 106.021(4)°, V = 1492.28(9) Ǻ³ and Z = 4.

The title compound (C₁₀H₉N₂)[Cr(C₆H₇NO₆)₂](C₁₀H₈N₂)∙2H₂O or (4,4´-bipyH)[Cr(ntaH)₂](4,4´-bipy)∙2H₂O (ntaH₃ is nitrilotriacetic acid) was synthesized by reaction of Cr(NO₃)₃∙9H₂O with 4,4´-bipyridine, and nitrilotriacetic acid with 4:2:1 molar ratio in aqueous solution. The crystal structure of this complex was identified using X-ray crystallography. The unit cell parameters are as follows:

a = 9.8501(3) Å, b = 13.157(2) Å, c = 26.842(4) Å, β = 104.807(7)°.

The final R value is 0.041 for 7747 independent reflections. The title compound crystallized in monoclinic system and belongs to P2₁/c space group.  The central Cr^III atom is coordinated by two tridentaid (ntaH₂) ligands and the resulted CrO4N2 set can be described as distorted octahedral geometry. The asymmetric unit contains two half of anionic complex, one 4, 4´-bipyridiniom ion, (4, 4´-bipyH)⁺, one neutral 4, 4´-bipyridine molecule and two non-coordinated water molecules. Intramolecular hydrogen bonds, π-π [centroid –centroid distances of 3.674 Ǻ], C-H…π, O-H…π and N-H…π stacking interactions [with distance of 3.714, 3.736 and 3.270 Å respectively], connect the various components into a supramolecular structures.

Zinc (II) complex, [Zn(25-MBTSC)₂I₂] (1), where (25-MBTSC = (E)-2-(2,5-dimethoxybenzaldehyde) thiosemicarbazone, has been synthesized from the reaction of ZnI₂ with 25-MBTSC in methanol as solvent at 25 ºC. It was characterized by elemental analysis (CHN) and is confirmed by single-crystal X-ray diffraction analysis. The complex 1 crystallizes in a triclinic system, with space group P^-ī, having one symmetry-independent Zn²⁺ ion coordinated in a distorted tetrahedral geometry by two S atoms of the 25-MBTSC ligand and by two I atoms. The thiosemicarbazone ligand 25-MBTSC acts as a monodentate ligand and coordinates via one S atom in η¹-S bonding mode to the zinc center.

New Schiff-base compound (E)-4-methoxy-N-(4-hydroxybenzylidene) aniline has been synthesized from the reaction of 4-hydroxybenzaldehyde with 4-methoxyaniline in methanol at 50ºC, and has been characterized by using elemental analysis and FT-IR spectroscopy. The crystal structure of the title compound has been determined by single crystal X-ray diffraction study. The title compound crystallizes in the orthorhombic, space group Pbcn with unit cell parameters a = 22.3813(5), b = 10.7477(2), c = 9.3623(2) Å, V = 2252.08(8) ų, Z = 8 and R = 0.03. The N1 = C7 imine bond length of 1.2839(14) Å is typical of a double bond. The molecule of the title compound is non planar and the dihedral angle between the two phenyl rings is 58.97 (32)º. There is a strong intermolecular hydrogen bond of the O∙∙∙H-C type forming one-dimensional chain.

The polymeric compound, {(C₁₀H₉N₂)[Mn(C₇H₃NO₄)₂].­(C₁₀H₈N₂).6H₂O}_n, was prepared by the reaction of manganese (II) nitrate with pyridine-2,3-dicarboxylic acid, (py-2,3-dcH₂) and 4,4'-bipyridine (4,4'-bipy) in a 1:2:4 molar ratio. The crystal system of the complex is monoclinic with space group P2₁/n and four molecules per unit cell. The unit cell parameters are: a = 22.2099(15) Å, b = 6.6599(4) Å,
c = 23.5921(16) Å and β = 104.014(3)­°.  The final R value was 0.04 based on 8960 reflections. The central atom is attached to two (py-2,3-dc)^2– ligands through their N and O atoms in a planar square arrangement and two O atoms from bridging carboxylate groups, forming polymeric chains. So, the anionic complex features six-coordinate Mn (III) with a distorted octahedral geometry. In the crystal structure, a wide range of non-covalent interactions consisting of hydrogen bonding (of the types O−H···O, O−H···N and C−H···O), ion pairing, and π–π (centroid-centroid distances of 3.607 and 3.721 Å), C−H···π (with H···π distance of 2.941 Å) and C=O···π (with O···π distances of 2.943, 3.702 and 3.743 Å)  stacking interactions stabilize the supramolecular structure.

The crystal structure of the title chiral Schiff base compound (E)-3,4-dimethoxy[(1-phenylethyl)iminomethyl]bezyne (1) was determined by single-crystal X-ray diffraction data. The title compound was further characterized by elemental analyses (CHN), FT-IR, ¹H-NMR and UV-Vis spectroscopic techniques. It crystallizes in the monoclinic space group P2₁ with unit cell parameters:
a = 19.0121 (2), b = 8.2507 (2), c = 9.7331 (4) Ǻ, β = 92.488 (2)°, V = 1525.33 (7) Ǻ³, Z = 4, R₁ = 0.0299, wR₂ = 0.787, R₁ = 0.0329, wR₂ = 0.0804.

The mercury (II) complex, Hg (Meca₂en)I₂ (1), containing bidentate Schiff base ligand  Meca₂en = N,N′-bis[(E)-2-benzylidenepropylidene]ethane-1,2-diamine, has been synthesized and characterized by elemental analyses (CHN) and ¹H-NMR spectroscopy. The crystal structure of 1 was determined using single-crystal X-ray diffraction. Structural investigation shows that 1 crystallizes in a monoclinic system, with space group P2₁/n. The Schiff base ligand Meca₂en acts as a bidentate ligand coordinating via two N atoms to mercury (II) ion.

Single crystals of Schiff base compound 2-[(2-chloro-4-nitrophenyl) iminomethyl] phenol (1) were grown by the slow evaporation technique at room temperature. The crystal structure of the title compound was determined by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P2₁, with two symmetry independent molecules. Intramolecular O-H···N hydrogen bonds form S(6) motifs in each molecule. Intermolecular C-H···O interactions connect the molecules into a three dimensional network.