Search results for "Geometry"
showing 10 items of 4487 documents
Crystal and molecular structure of anhydrous betaine, (CH3)3NCH2CO2
1999
Abstract 1–Carboxy–N,N,N–trimethylmethanamanium inner salt or anhydrous betaine, (CH3)3NCH2CO2, FW=117.15 gmol −1 , crystallizes in the orthorhombic space group Pnma with a=14.544(2) A , b=6.859(3) A , c=6.131(1) A , V=611.7(3) A 3 , Z=4, D x =1.27 Mgm −3 , λ (MoK α )=0.71073 A , μ =0.091 mm −1 . The structure was resolved by direct methods and refined by least-square calculations to R=0.038 for 531 reflections. Observed changes in bond angles imply that there is a repulsion between nitrogen and oxygen. The melting point (measured at onset) is 570 K. FTIR spectra of anhydrous betaine and monohydrate were recorded. Clear differences were found between the two compounds based on infrared (i.r…
Synthesis, spectroscopic and structural characterization of [Cu(phen)(C5O5)(H2O)]·H2O, [Ni(terpy)(C5O5)(H2O)]·H2O and [Ni(terpy)2](NO3)2·0.5H2O
2005
Abstract The new mononuclear complexes [Cu(phen)(C5O5)(H2O)]·H2O (1), [Ni(terpy)(C5O5)(H2O)]·H2O (2) and [Ni(terpy)2](NO3)2·0.5H2O (3) [phen=1,10-phenanthroline, C 5 O 5 2 − =dianion of the 4,5-dihydroxycyclopent-4-ene-1,2,3-trione and terpy=2,2′:6′,2″-terpyridine] have been synthesized and characterized by single-crystal X-ray diffraction. The copper atom of 1 has a distorted square pyramidal environment with two phen-nitrogen and two croconate-oxygen atoms building the equatorial plane and a water molecule in the apical position. The nickel atom of 2 exhibits a distorted NiN3O3 octahedral coordination, which may be described either as tetragonally compressed or as skewed trapezoidal bipyr…
Squarate and croconate in designing one- and two-dimensional oxamidato-bridged copper(II) complexes: synthesis, crystal structures and magnetic prope…
2001
Abstract The reaction of squarate (C4O42–, dianion of 3,4-dihydroxycyclobut-3-ene-1,2-dione) and croconate (C5O52–, dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione) with the dinuclear 〚Cu2(apox)〛2+ copper(II) complex 〚H2apox = N,N’-bis(3-aminopropyl)oxamide〛 in aqueous solution affords the compounds of formula 〚Cu2(apox)(C4O4)(H2O)2〛n·n H2O (1) and 〚Cu4(apox)2(C5O5)2〛·6 H2O (2). Crystals of 1 are monoclinic, space group C2/c, with a = 12.5527(9), b = 7.4161(6), c = 18.5198(12) A, β = 100.578(6)° and Z = 4. Crystals of 2 are triclinic, space group P 1 with a = 9.732(5), b = 9.795(2), c = 10.285(3) A, α = 84.95(2), β = 77.30(3), γ = 85.61(3)° and Z = 1. The structure of complex 1 consist…
The structure of polymeric diaquo-di-μ-hydroxo-bis-μ-(nicotinato-N-oxide)-bis-μ-(nicotinato-N-oxide)tricopper(II)
1981
Abstract The new unusual polymeric copper(II) complex with nicotinate N-oxide (N-nicO), [Cu3(N-nicO)4(OH)2(H2O)2]n was prepared and its crystal and molecular structure was determined from three-dimensional X-ray diffraction data. The crystals belong to the triclinic space group P 1 (No. 2). The cell parameters are a = 7.881(9), b = 9.658(11), c = 10.368(12) A, α = 97.32(9), β = 110.38(9), γ = 109.53(9)°, V = 670(1) A3, dobs = 1.94 (dcalc = 2.02) and Z = 1. The structure was refined to a final R-value of 4.13%. The complex is a polymeric, linear chain along the c-axis, and its structure units are connected with each other through two N-oxide oxygen atoms. There are three copper atoms (Cu1, C…
Localized excitation effect on dipole moments of oligophenylenevinylenes in their excited Franck–Condon state
2010
Abstract The results from electrooptical absorption measurements (EOAM) on the ground and excited Franck–Condon state dipole moments of oligophenylenevinylenes in 1,4-dioxane and cyclohexane are presented. The dipole moments of quadrupolar dyes in the ground state are not equal zero. This means that one of the functional end groups of these molecules is not on the axis or on the plane with the central part of the molecule. Such a conclusion is confirmed by the quantum-chemical and semi-empirical recalculations. Owing to disorder in the ground-state geometry of the dyes the π–π conjugated system is located on mostly the plane part of the molecule and in the main this part absorbs the light. …
Synthesis, structure and biological properties of several binary and ternary complexes of copper(II) with ciprofloxacin and 1,10 phenanthroline
2009
In this study, a new binary complex [Cu(HCip) 2 ](NO 3 ) 2 · 6H 2 O ( 1 ) has been synthesized and then characterized by X-ray structure analyses. In this compound, each ciprofloxacin acts as a bidentate ligand resulting in a crystallographically planar configuration; the nitrate anions are located in apical positions with an axial distance significantly larger than the equatorial distances, which would be consistent with a very weak metal ion interaction due to the Jahn–Teller effect. In addition, both the synthesis and characterization of two new ternary complexes of ciprofloxacin–copper(II)–1,10-phenanthroline, [Cu(phen)(Cip)](NO 3 ) · 4H 2 O ( 2 ) and Cu(phen)(HCip)(NO 3 ) 2 · H 2 O (…
Synthesis ofo-thiatelluraphenylenezirconocenes. X-ray crystal structure of
1992
o-Thiatelluraphenylenezirconocene complexes were obtained in good yield by reaction of dilithiumo-benzenthiatelluride with zirconocene dichlorides. These compounds represent the first examples of heterodichalcogenaphenylene bent metallocences. They were characterized by spectroscopic methods and the effect on the n.m.r. results of stepwise substitution of one and two Te atoms for S is discussed.
Crystal structure and spectroscopic study of [Cu(BPCA)(OH2)(O2CCH3)·H2O complex; BPC = N-2-pyridinylcarbonyl-2-pyridinecarboximidate anion
1989
Abstract The crystal and molecular structure of the [Cu(BPCA)(OH2)(O 2CCH3]·H2O complex (BPCA = N-2-pyridinylcarbonyl-2-pyridinecarboximidate anion) has been determined by X-ray diffraction methods. It crystallizes in the triclinic space group P l with two formula units in a cell of dimensions: a = 7.416(2), b = 8.632(4), c = 13.034(3) A, α = 74.55(3), β = 84.84(3), γ = 81.04(5)°. Least-squares refinement of 2534 reflections with I > 2.5σ(I) and 218 parameters gave a final R = 0.047 and Rw = 0.049. The structure consists of discrete [Cu(BPCA)(OH2)(O2CCH3)] neutral units linked through hydrogen bonding. The coordination geometry around copper ions can be described as tetragonal square pyrami…
ChemInform Abstract: Dissymmetric Calix(4)arenes with C2 and C4 Symmetry.
2010
Synthese de tetrahydroxy-octamethyl [1 4 ] Metacyclophane a partir de 3,4-dimethylphenol. Le tetrahydroxy-octamethyl [1 4 ] Metacyclophane reagit avec le bromoacetate d'ethyle pour donner tetrakis [(ethoxycarbonyl) methoxy]-octamethyl [1 4 ] Metacyclophane qui est analyse par diffraction RX
Organotin(IV) chloride complexes with phosphocholine and dimyristoyl-L-?-phosphatidylcholine
2000
Several complexes of R n SnCl 4-n (R = Me, Ph, n = 1-3; R = nBu, n = 2, 3) with phosphocholine and dimyristoyl-L-α-phosphatidylcholine (phospholipid) have been synthesized and characterized by means of Mossbauer spectroscopy and NMR. Triorganotin chlorides form complexes of (R 3 SnCl) 2 .L stoichiometry with a trigonal bipyramidal pentacoordinate tin environment, while the others form 1:1 complexes with an octahedral hexacoordinate tin environment, with the ligands coordinating through anionic phosphodiester moieties in all cases.