Cl Plane Research Articles

Considerations of a thick lens formula for intraocular lens power calculation

BackgroundIn recent years, some lens manufacturers have committed to providing lens shape data for some of their lens models. The purpose of this study is to present a strategy for prediction of intraocular lens power and residual refraction based on a pseudophakic model eye containing 5 refractive surfaces and to show its applicability using worked examples. MethodsA pseudophakic model eye with a thin spectacle correction, a thick cornea (radius of curvatures for both surfaces and central thickness) and a thick IOL (either radius of curvatures RLa and RLp for front and back surface or equivalent power PL and Coddington factor CL; and either central thickness LT or edge thickness and optic diameter) was set up. Calculations were performed based on linear Gaussian optics (vergence formulae). Formulae were provided to derive the lens power/shape and the residual equivalent spectacle refraction SEQ. From the lens shape the location of the haptic plane HP, the image sided principal plane of the lens HL, and the ocular magnification OM were extracted. ResultsThe calculation of a thick intraocular lens and the prediction of residual refraction is presented with reference to 3 working examples: A) lens varied in PL and shifted with its haptic plane keeping the CL constant, B) lens varied in CL and shifted with its haptic plane keeping PL constant, and C) CL and PL of the lens varied keeping its haptic plane position in the eye constant. For each combination of parameters (PL, CL, or haptic plane shift) the parameters influencing SEQ, OM and HL-HP were analysed. ConclusionSome modern optical biometers currently on the market provide the radii of curvature of both corneal surface and all relevant distances in the eye. With additional data on the lens shape, it would be possible to improve lens power calculations by switching from thin to thick lens models for the cornea and for the lens. This would overcome one of the major drawbacks of current lens power calculation methods.

Crystal structure of (N (1)-benzyl-N (1),N (2),N (2)-tri-methyl-ethane-1,2-di-amine-κ(2) N,N')di-chloridomercury(II).

In the structure of the title compound, [HgCl2(C12H20N2)], the Hg(II) atom has a distorted tetra-hedral coordination sphere defined by two tertiary amine N-atom donors, as well as two Cl(-) anions [the dihedral angle between the N-Hg-N and Cl-Hg-Cl planes is 82.80 (9)°]. The five-membered chelate ring adopts an envelope conformation, with puckering parameters of Q(2) = 0.446 (6) Å and ϕ(2) = 88.8 (6)°, with the two amine CH3 substituents on opposite sides of the ring. In the crystal, the mol-ecules are linked by C-H⋯Cl inter-actions into a zigzag chain parallel to [101].

Molecular structure and barriers to internal rotation of α-naphthalenesulfonyl chloride: a study by gas-phase electron diffraction and quantum chemical calculations

α-Naphthalenesulfonyl chloride, α-NaphSC, was studied by gas-phase electron diffraction (GED) and quantum chemical calculations (HF/6-311 + G**, HF/aug-cc-pVDZ, B3LYP/cc-pVDZ, B3LYP/cc-pVTZ, B3LYP/aug-cc-pVDZ, B3LYP/aug-cc-pVTZ, MP2/cc-pVDZ, and MP2/cc-pVTZ). The calculations predict the existence of two conformers with C1 (I) and Cs (II) symmetries. The most stable conformer I has an enantiomer. The experimental data of α-NaphSC obtained at 370(5) K could be best fitted by a C1 symmetry model indicating that only this form exists in the gas-phase. In this model the Cα–S–Cl plane deviates from the perpendicular orientation relative to the plane of the naphthalene skeleton. Under the applied experimental conditions, the mole fraction of a second less stable conformer II of α-NaphSC predicted by calculations is no more than 1 %. The following geometrical parameters of conformer I were obtained from the experiment (A and °; uncertainties are in parentheses): rh1(C–H) = 1.082(6), rh1(C–C)cp = 1.407(3), rh1(C–S) = 1.764(5), rh1(S–O)av = 1.425(3), rh1(S–Cl) = 2.051(5), ∠C–Cα–C = 122.5(1), ∠Cα–S–Cl = 101.5(10); C9–C1–S–Cl = 71.4(21). The calculated barriers to internal rotation of the sulfonyl chloride group exceed considerably the thermal energy values corresponding to the temperatures of the GED experiments. Natural bond orbitals analysis of the electron density distribution was carried out to explain the peculiarities of the molecular structure of the studied compound and the deviation from the structures of β-NaphSHal molecules and their benzene analogs.

Pyridazine-Based N-Heterocyclic Carbene Complexes and Ruthenium-Catalyzed Oxidation Reaction of Alkenes

[Ru2Cl(L)(CH3CN)4](PF6)3 (1, L = 3,6-bis(N-(pyridylmethyl)imidazolylidenyl)pyridazine), [Cu3La3](PF6)3 (2, La = 3-(N-(pyridylmethyl)imidazolylidenyl)-6-(N-(pyridylmethyl)imidazolylonyl)pyridazine), [Pd2(allyl)2L](PF6)2 (3), [Pd2(allyl)2Lb2](PF6)2 (4, Lb = N-pyridylmethylimidazole), and [NiLc2](PF6)2 (5, Lc = 3-(N-(pyridylmethyl)imidazolylidenyl)-6-methoxylpyridazine) have been synthesized and fully characterized by NMR spectroscopy, elemental analysis, and X-ray diffraction analysis. In complex 1, ligand L binds to two Ru(II) centers, forming a well-behaved Ru2(L)Cl plane with a five-membered metallocyclic ring. Complex 2 is trinuclear, containing a triangular Cu3 unit bonded together by three 3-(N-(pyridylmethyl)imidazolylidenyl)-6-(N-(pyridylmethyl)imidazolylonyl)pyridazine, where one imidazolylidene was oxidized into imidazolone. Deprotonation reaction with Ag2O in CH3CN and CH3OH resulted in C–N cleavage of the imidazolium salt, and subsequent reaction with [Pd(allyl)Cl]2 and Ni(PPh3)2Cl2 gave 4 and 5...

2,2′-Bis(diphenylphosphanyl)-1,1′-binaphthyl-κ2P,P′]chlorido(4-methylphenylsulfonyl-κS)palladium(II) dichloromethane trisolvate monohydrate

In the title compound, [Pd(C7H7O2S)Cl(C44H32P2)]·3CH2Cl2·H2O, the geometry around the metal atom is distorted square planar, with a twist angle between the P—Pd—P and S—Pd—Cl planes of 28.11 (2)°. The two Pd—P bond lengths differ by about 0.04 Å and the biphosphane bite angle is slightly obtuse [92.92 (2)°]. There are three dichloro­methane and one water mol­ecule co-crystallized with the palladium mol­ecule, all with atoms in general positions. Alternating water and palladium mol­ecules form four-membered cyclic units through O—H⋯Cl and O—H⋯O hydrogen bonding. One of the dichloromethane solvent molecules is disordered over two positions in a 0.55:0.45 ratio.

(Benzyl phenyl sulfoxide-κO)dichloridodiphenyltin(IV)

The SnIV atom in the title compound, [Sn(C6H5)2Cl2(C13H12OS)], displays a distorted C2Cl2O trigonal–bipyramidal coordination environment, with a mean Sn—C distance of 2.121 (9) Å and with Sn—O = 2.331 (2) Å. The SnIV atom is displaced by 0.169 (2) Å from the equatorial C2Cl plane towards the direction of the second axially bonded Cl atom.

Dichlorido[(S)-N-(1-phenylethylidene)-1-(pyridin-2-yl)ethanamine-κ2N,N′]zinc(II) dichloromethane solvate

In the title compound, [ZnCl2(C15H16N2)]·CH2Cl2, the Zn(II) atom has a distorted tetra­hedral coordination by two Cl atoms and two N atoms from the organic ligand [the average Zn—N and Zn—Cl bond lengths are 2.060 (4) Å and Zn—Cl = 2.179 (16) Å, respectively]. The dihedral angle between the N—Zn—N and Cl—Zn—Cl planes is 89.9 (1)°. The phenyl ring forms a dihedral angle of 40.6 (5)° with the imine plane.

First-principles study of defect-induced potentials inCa2CuO2Cl2

The local atomic and electronic structures of the Na and K impurities and the vacancy at the Ca site (${\text{Na}}_{\text{Ca}}$, ${\text{K}}_{\text{Ca}}$, and ${\text{V}}_{\text{Ca}}$), and their induced electrostatic potentials in ${\text{Ca}}_{2}{\text{CuO}}_{2}{\text{Cl}}_{2}$ have been investigated by using the $\text{GGA}+U$ approach. It is found that ${\text{Na}}_{\text{Ca}}$ and ${\text{K}}_{\text{Ca}}$ are markedly relaxed toward the Cl plane from the original Ca site. When ${\text{V}}_{\text{Ca}}$ exists, its neighboring Ca approaches the vacancy site, and Cl and O are relaxed outwardly. From the analyses of the local electrostatic potentials at the Cu and O sites, we found that the ${\text{Na}}_{\text{Ca}}$-induced potential is almost the same as the ${\text{K}}_{\text{Ca}}$-induced potential, and the ${\text{V}}_{\text{Ca}}$-induced potential is about twice as large. The defect-induced potentials are modeled by point charges under a dielectric medium. The atomic relaxation is found to increase the effective dielectric constants approximately threefold, indicating the importance of its contribution to the screening of the potential. The stabilization energies of small polarons obtained by the total energy differences are close to the potential energies. These results suggest that the interaction between the polaron and defects is well described by a positive charge of the polaron under the defect-induced electrostatic potential.

Dichlorido[(S)-(1-phenyl-ethyl)(2-pyridyl-meth-yl)amine-κN,N']zinc(II).

In the title compound, [ZnCl2(C14H16N2)], the ZnII atom is coordinated by two N atoms and two Cl atoms in an approximately tetra­hedral arrangement. The dihedral angle between the N—Zn—N and Cl—Zn—Cl planes is 88.06 (8)°. The H atoms on the chiral C atom and the adjacent N atom have an anti conformation.

InGaN Growth with Indium Content Controlled by GaN Growth Plane

ABSTRACTHighly spatially resolved cathodoluminescence (HRCL) imaging and electron backscattering pattern (EBSP) study of InGaN microcrystals were achieved. InGaN grown by the nitridation of a mixture of GaN microcrystals and indium sulfide powders with ammonia at 1000°C had crystal habit with twelve prismatic planes. The prismatic planes were grouped into two groups: the first group is pentagonal shaped planes yielding blue CL (420nm) and rectangular planes without luminescence. EBSP showed that the pentagonal shaped planes are indexed to the {11-20} a-plane and the rectangular plane to the {1-100} m-plane. HRCL imaging showed InGaN accumulated at the V pits on the basal plane. The obevation indicated that the crystal qualty of InGaN and the indium contents incorpated were controlled by the indices of GaN growth planes on which InGaN grew.

{Bis[2-(3,5-dimethylpyrazol-1-yl)ethyl]amine-κ2 N,N′}dichloridozinc(II) methanol solvate

In the title compound, [ZnCl2(C14H23N5)]·CH3OH, the Zn atom is coordinated by two N atoms and two Cl atoms in an approximately tetrahedral arrangement. The dihedral angle between the N—Zn—N and Cl—Zn—Cl planes is 89.69 (5)°. The methanol solvent molecule takes part in the formation of the hydrogen-bond system.

Dichlorido[N,N,N′,N′-tetramethylcyclohexane-1,2-diamine-κ2N,N′]zinc(II)

In the title compound, [ZnCl2(C10H22N2)], the ZnII ion coordinates to the N atoms of tetra­methyl­cyclo­hexane-1,2-diamine and to two chloride ions in an approximately tetra­hedral arrangement. The N—Zn—N and Cl—Zn—Cl planes are approximately orthogonal, with a dihedral angle of 89.7 (2)° between them. Four C atoms of the cyclohexane ring, together with their attached H atoms, are disordered equally over two sites.

Anomeric Interactions in Pentafluoroethylimidosulfurous Dichloride, CF3CF2N=SCl2: Structural, Conformational and Configurational Properties in the Gaseous and Condensed Phases

AbstractThe structural, conformational, and configurational properties of pentafluoroethylimidosulfurous dichloride (CF3CF2N=SCl2) have been studied by vibrational spectroscopy [IR (vapor) and Raman (liquid)] and quantum chemical calculations [HF, B3LYP and MP2 approximations using the 6‐311+G(d) and 6‐311+G(2df) basis sets]. CF3CF2N=SCl2 exists in the liquid phase as a single (Z) form (C–N bond synperiplanar with respect to the Cl–S–Cl plane; C1 symmetry). The structure was also determined by X‐ray diffraction analysis of a single crystal grown in situ at low temperature. The crystalline solid at 159 K (monoclinic, P21/c, a = 5.2466(10), b = 15.376(3), c = 18.730(3) Å, β = 96.391(3)°, Z = 8) consists of two crystallographically inequivalent (Z) forms. The results are discussed in terms of both hyperconjugative electronic effects and of natural bond orbital (NBO) calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Ab Initio Calculation of Room Temperature Ionic Liquid 1-Ethyl-3-Methyl-Imidazolium Chlorocuprate (I)

The Hartree-Fock method has been employed to investigate the electronic structures of EMIM +(1-ethyl-3-methyl-imidazolium +), CuCl − 2, Cu 2Cl − 3, CuCl 2 −, EMIM +-CuCl − 2, EMIM +-Cu 2Cl − 3, and EMIM +-CuCl 2− 3 pairs. Full optimization and frequency analyses of EMIM +, CuCl − 2, Cu 2Cl − 3, CuCl 2− 3, eight initial EMIM +-CuCl − 2, six EMIM +-Cu 2Cl − 3, and four EMIM +-CuCl 2− 3 geometries have been carried out using Gaussian-94 soft-package at 6-31+G(d,p) basis set level for hydrogen, carbon, nitrogen, chlorine atoms and Hay-Wadt effective core potential for copper atom. The electronic structures of lowest energy of EMIM +-CuCl − 2, EMIM +-Cu 2Cl − 3, EMIM +-CuCl 2− 3, single EMIM +, CuCl − 2, Cu 2Cl − 3, and CuCl 2 3 − have been comparatively studied. The calculated results showed that EMIM +-CuCl − 3 pair conformer of lowest energy was five ring parallel to Cl—Cu—Cl with 3.2 Å distance, EMIM +-CuCl 2− 3 pair conformer of lowest energy was five ring parallel to CuCl 2 3 −plane with 3.4 Å distance, and the optimized EMIM +-Cu 2Cl − 3 pair conformer of lowest energy was five ring perpendicular to Cl—Cu—Cl—Cu—Cl plane with 3.0 Å distance between the terminal Cl atoms and the 5-ring of EMIM +. The cohesion between cations and anions is brought about by C—H … Cl hydrogen bonds that are reinforced by charge assistance. The frequency analyses suggested that all stationary points are minimum because of no appearing of imaginary frequency. The assigned frequencies were in agreement with the experimental report. The low energy of interaction because of the bulky asymmetry of EMIM + and the charge dispersion of cation and anion leads to the low melting point of the ionic liquids, EMIM +-CuCl − 2, EMIM +-Cu 2Cl − 3, and EMIM +-CuCl 2− 3. The interaction energy of EMIM +-CuCl − 2, EMIM +-Cu 2Cl − 3, and EMIM +-CuCl 2− 3 is 309.0 kJ/mol, 316.8 kJ/mol, and 320.2 kJ/mol, respectively. The relationship of interaction energy via distance between cations and anions was also investigated by single point energy scan.

Dichloro[2,2′-(methylenedithio)bi-1,3-thiazole-κ2 N,N′]cobalt(II)

In the title complex, [CoCl2(C7H6N2S4)], 2,2′-(methylenedithio)bi-1,3-thiazole acts as a bidentate ligand and chelates one CoII ion through the two N atoms to give an eight-membered symmetric unit. The CoII ion is located on a twofold axis and displays a slightly distorted tetrahedral coordination environment, where the two Cl− anions occupy the remaining coordination sites. The N—Co—N and Cl—Co—Cl planes are nearly perpendicular, with a dihedral angle of 88.0 (3)°.

(2,2′-Biquinoline-κ2N,N′)dichloropalladium(II), -copper(II) and -zinc(II)

In the three title complexes, namely (2,2'-biquinoline-kappa(2)N,N')dichloropalladium(II), [PdCl2(C18H12N2)], (I), and the corresponding copper(II), [CuCl2(C18H12N2)], (II), and zinc(II) complexes, [ZnCl2(C18H12N2)], (III), each metal atom is four-coordinate and bonded by two N atoms of a 2,2'-biquinoline molecule and two Cl atoms. The Pd(II) atom has a distorted cis-square-planar coordination geometry, whereas the Cu(II) and Zn(II) atoms both have a distorted tetrahedral geometry. The dihedral angles between the N-M-N and Cl-M-Cl planes are 14.53 (13), 65.42 (15) and 85.19 (9) degrees for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.

Dichloro[(6R,7S,8S,14S)-(-)-sparteine-kappa(2)N,N']nickel(II).

In the title compound, [NiCl(2)(C(15)H(26)N(2))], the chiral alkaloid (6R,7S,8S,14S)-(-)-L-sparteine acts as a bidentate ligand, with two chloride ligands occupying the remaining coordination sites, producing a slightly distorted tetrahedron. The N-Ni-N plane in the title complex is twisted by 81.31 (11) degrees from the Cl-Ni-Cl plane. Other distortions of the tetrahedron are discussed.

Polymorphism, Structure, Guest Conformation, and Dynamics in the Inclusion Compound of 1,2-Dichloroethane with Tris(5-acetyl-3-thienyl) Methane: a Combined Single Crystal and Powder X-ray Diffraction, 13C CP/MAS, and 2H NMR Study

Various physicochemical characterization techniques were used to study the structure and guest dynamics of the 1,2-dichloroethane/tris (5-acetyl-3-thienyl) methane (TATM) inclusion compound. This complex was observed to crystallize in two forms, a triclinic P-1 structure and a less usual monoclinic P21/c form. The X-ray structures indicate that the TATM molecules form “bottleneck” channels parallel to the crystallographic c axis in both forms and that the guests exist exclusively in the trans form. Solid-state deuterium NMR spectroscopy was used to study the dynamics of the 1,2-dichloroethane-d4 guest in the triclinic form. The simplest model consistent with the experimental NMR spectra was based on internal rotation about the C−C bond (a trans/gauche conformational equilibrium). As this was not consistent with the X-ray structure, another model was developed where the trans conformer performs 180° flips about an axis through the center of symmetry of the guest and perpendicular to the Cl−C−C−Cl plane. Th...

Neutron diffraction study of the oxychloride layered perovskite, (CuCl)LaNb2O7

The structure of the oxychloride layered perovskite, (CuCl)LaNb2O7, has been examined by neutron diffraction. Rietveld refinement of room temperature neutron TOF data, while consistent with the previous X-ray study, allows for an improved modeling of the structure. The structure consists of double perovskite layers (LaNb2O7) separated by copper chloride layers. The copper is octahedrally coordinated, bridging between apical oxygens from the perovskite layer and surrounded by four chlorines in the CuCl plane; this gives rise to edge-sharing CuO2Cl4 octahedra. The chlorines within the CuCl plane were found to move off the ideal (0,0,1/2) position to a more general position, (x,0,1/2). This disorder leads to a combination of four short and two long distances, common to the Jahn–Teller distorted environments for d9 copper. Structural details are discussed with respect to their influence on the chlorine disorder.

Synthesis, Characterization, and Theoretical Study of Stable Hydride−Azavinylidene Osmium(IV) Complexes

The dihydride−dichloro complex OsH2Cl2(PiPr3)2 (1) reacts with cyclohexanone oxime in toluene under reflux to give after 12 h (2), which can be also obtained by reaction of the oximate compound, (3) with HCl. Complex OsHCl2{NC(CH3)2}(PiPr3)2 (4) has been similarly prepared by treatment of compound OsH2Cl{κ-N,κ-O[ONC(CH3)2]}(PiPr3)2 (5) with HCl. When the reaction of 1 and cyclohexanone oxime, in toluene under reflux, was quenched after 1 h, a mixture of 1, 2, 3, and the trichloroazavinylidene (6) was obtained. The structures in the solid state of 2 and 6 have been determined by X-ray diffraction studies. In both cases, the geometry around the metal center can be described as a distorted octahedron with the phosphorus atoms of the phosphines occupying trans positions and the CN group and the carbon atoms bonded to this group lying in a plane that is parallel to the Cl−Os−Cl plane. CCSD(T)//B3LYP calculations on the model complexes OsXCl2(NCH2)(PH3)2 [X = H (2t), X = Cl (6t)] state that the above-mentioned conformation is 15.3 (2t) or 12.1 (6t) kcal mol-1 more stable than that with the azavinylidene ligand parallel to the P−Os−P plane. In solution the azavinylidene ligands of 2 and 4 rotate around the Os−N−C axis. The activation parameters of the process are ΔH⧧ = 14.4 ± 0.8 kcal mol-1 and ΔS⧧ = −1.1 ± 1.3 cal mol-1 K-1 for 2 and ΔH⧧ = 13.1 ± 0.8 kcal mol-1 and ΔS⧧ = 0.0 ± 2.8 cal mol-1 K-1 for 4.