scholarly journals Spektroskopische und strukturelle Aspekte der Protonierung von Tetraaza[14]annulen-Dianionen / Spectroscopic and Structural Aspects of the Protonation of Tetraaza[14]annulene Dianions

1996 ◽  
Vol 51 (9) ◽  
pp. 1255-1266 ◽  
Author(s):  
H. Schumann ◽  
B. Neumann ◽  
H.- G. Stammler
Keyword(s):  
Structural Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
Crystal System ◽  
Additional Information ◽  
R Factor ◽  
Vis Spectroscopy ◽  
First Time ◽  
Structural Aspects ◽  
C Nmr

The effects of increasing protonation upon two [ 14]annulene dianions prepared by reaction of LiCH3 with 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][l,4,8,l l]tetraazacyclotetradecine (IIIb) and 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i][l,4,8,l 1 ]tetraazacyclotetradecine (IIIc) have been studied by 1H, 13C NMR and UV-VIS spectroscopy in solution. The crystal structures of the diprotonated macrocycle IIIb x 2 HPF6 (lIb) and of the neutral macrocycle IIIc have been determined by X-ray diffraction. For lIb, the crystal system is monoclinic with a space group of P21/n: a = 12.019(3), b = 13.864(6), c = 33.547(9) Å, β = 99.82(2)°, Z = 8 . The final R factor is 0.083 for 5520 observed reflections (745 variables). For IIIc, the crystal system is triclinic with a space group of P1̄: a = 9.923(8), b = 11.633(9), c = 14.318(12) Å, ct = 110.50(6)°, β = 98.86(7)°, 7 = 103.12(6)°, Z = 2. The final R factor is 0.081 for 2174 observed reflections and 191 variables. Comparison of these structural data together with those obtained from the literature for the deprotonated macrocycle IVb and a wide variety of substituted [ 14]annule derivatives allows for the first time a discussion of protonation effects upon the highly π-conjugated pentadiimidato moiety. Additional information is derived from NMR and UV-VIS data.

scholarly journals Solid state and solution structural investigation of homoleptic tin(IV) alkoxide compounds. Part I. Sn(O—t-Bu)4 and [Sn(O—i-Pr)4•HO—i-Pr]2

1991 ◽  
Vol 69 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Mark J. Hampden-Smith ◽  
Teresa A. Wark ◽  
Arnold Rheingold ◽  
John C. Huffman
Keyword(s):  
Solid State ◽  
Variable Temperature ◽  
Equilibrium Concentration ◽  
Molecular Structures ◽  
Monoclinic Crystal System ◽  
Monoclinic Crystal ◽  
Space Group ◽  
Crystal System ◽  
Reversible Dissociation ◽  
C Nmr

The crystal and molecular structures of Sn(O—t-Bu)4• and [Sn(O—i-Pr)4•HO—i-Pr]2 have been determined by single-crystal X-ray diffraction. Sn(O—t-Bu)4 crystallizes in the monoclinic crystal system with space group C2/c, where a = 17.382(6) Å, b = 8.742(2) Å, c = 15.518(5) Å, β = 116.44(1)°, Z = 4, and R = 2.5%. Sn(O—t-Bu)4 is monomeric in the solid state, with a distorted tetrahedral tin coordination environment. [Sn(O—i-Pr)4•HO—i-Pr]2 crystallizes in the monoclinic crystal system with space group P21/n, where a = 11.808(3) Å, b = 14.356(3) Å, c = 12.380(2) Å, β = 95.27(2)°, Z = 2, and R = 4.9%. [Sn(O—i-Pr)4•HO—i-Pr]2 exhibits an edge-shared, bi-octahedral structure in the solid state that is distorted due to the presence of asymmetric hydrogen bonding between axially coordinated alcohol ligands and an isopropoxide ligand.13C NMR and IR spectroscopic data have been recorded for Sn(O—t-Bu)4 and Sn(O—t-Bu-d9)4 to establish criteria for unambiguous identification of solution structures of tin(IV) alkoxides. It is demonstrated that the two-bond [Formula: see text] coupling constant is larger for terminal alkoxide ligands than for μ2-alkoxide bridges, and the ν(Sn—O) stretching frequency has been assigned. The dynamic solution behaviour of [Sn(O—i-Pr)4•HO—i-Pr]2 has been studied using variable temperature 1H and 13C NMR spectroscopy. The data obtained are consistent with a process that involves rapid reversible dissociation of isopropanol at room temperature. Upon cooling, the equilibrium concentration of the species with coordinated alcohol increases, and the molecule undergoes rapid intramolecular proton transfer (AG≠ < 11.9 kcalmol−1). Upon further cooling, the 13C NMR data are consistent with a solution structure analogous to that found in the solid state. Key words: tin, alkoxide, NMR, dynamic, structure.

Magnetic, Spectral and Structural Aspects of Spin Transitions in Iron(II) Complexes of 2-(Pyrazol-3-yl)pyridine and 3-(Thiazol-2-yl)pyrazole

1999 ◽  
Vol 52 (2) ◽  
pp. 109 ◽  
Author(s):  
Lucia S. Harimanow ◽  
Kristian H. Sugiyarto ◽  
Donald C. Craig ◽  
Marcia L. Scudder ◽  
Harold A. Goodwin
Keyword(s):  
Hydrogen Bonding ◽  
Hysteresis Loop ◽  
Room Temperature ◽  
Thermal Hysteresis ◽  
Structural Data ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Thermal Hysteresis Loop ◽  
Lower Temperature ◽  
Structural Aspects

Tris(ligand)iron(II) complexes of 2-(pyrazol-3-yl)pyridine (3ppH) and 3-(thiazol-2-yl)pyrazole (3tpH) undergo temperature-induced singlet (1A1) ⇔ quintet (5T2) transitions. The transition in [Fe(3ppH)3] [CF3SO3]2.2H2O is continuous and centred above room temperature while that in the anhydrous triflate salt is discontinuous and is centred below room temperature. The latter transition occurs via a thermal hysteresis loop of width 12 K, Tc↓ and Tc↑ being 229 and 241 K, respectively. The displacement of the transition to lower temperature in the anhydrous salt is believed to be associated with the loss of hydrogen bonding involving the uncoordinated pyrazole >NH group and solvate water. In [Fe(3tpH)2(3tp)] [ClO4].2H2O and [Fe(3tpH)2(3tp)] [BF4].2H2O (3tp is the deprotonated ligand) continuous transitions are observed, centred below room temperature. In these instances the displacement is consistent with the intrinsically weaker field of the bidentate system containing two five-membered heterocycles. Structural data were obtained for [Fe(3ppH)3][CF3SO3]2.2H2O, [Fe(3tpH)3] [BF4]2.1·5H2O and [Ni(3tpH)3] [BF4]2.2(3tpH). The average metal–nitrogen distances in the complexes are 1·97, 2·18 and 2·09 Å, severally. The large difference in the distances for the two iron complexes arises from the different ground states: a singlet for the 3ppH complex and a quintet for the 3tpH complex. In all three salts there is extensive hydrogen bonding involving the pyrazole >NH groups, the anions and the solvate molecules. [Fe(3ppH)3] [CF3SO3]2.2H2O: monoclinic, space group P21/c, a 12·33(1), b 24·44(1), c 12·55(1) Å, β 115·27(4)°, Z 4. [Fe(3tpH)3] [BF4]2.1·5H2O: monoclinic, space group C 2/c, a 41·56(2), b 16·418(3), c 18·154(7) Å, β 106·94(2)°, Z 8. [Ni(3tpH)3] [BF4]2.2(3tpH):P bcn, a 14·928(2), b 15·310 (3), c 17·882 (3) Å, Z 4.

Structural Systematics of Metal Acetylide Complexes: X-Ray Studies of Some 'Extended-Chain' Gold σ-Acetylide Complexes

1997 ◽  
Vol 50 (10) ◽  
pp. 991 ◽  
Author(s):  
Ian R. Whittall ◽  
Mark G. Humphrey ◽  
David C. R. Hockless
Keyword(s):  
Ground State ◽  
Structural Data ◽  
Monoclinic Space Group ◽  
Confidence Limits ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Back Bonding ◽  
Ground State Geometry

The structures of Au(4-C≡CC6H4XYC6H4-4′-NO2)(PPh3) (XY = (E )-CH=CH (1), (Z)-CH=CH (2), C≡C (3), N=CH (4)) have been determined by single-crystal X-ray diffraction analyses, refining by full-matrix least-squares analysis. For (1), crystals are triclinic, space group P-1, with a8·847(1), b 17·870(4), c 19·705(3) Å, α116·25(1), β 93·33(1), γ 92·64(2)˚, Z 4, 6747 unique reflections (703 parameters), converging at R 0·025 and Rw 0·029. For (2), crystals are monoclinic, space group P 21/a, with a 10·718(6), b 19·398(5), c14·469(3) Å, β 108·96(2)˚, Z 4, 3295 unique reflections (352 parameters), converging atR 0·040 and Rw 0·034. For (3), crystals are triclinic, space group P-1, with a 10·671(4), b 17·599(7), c 18·220(8) Å, α 116·31(3), β 105·00(4), γ 95·08(4)˚, Z 4, 4828 unique reflections (703 parameters), converging at R 0·043 and Rw 0·030. For (4), crystals are triclinic, space group P-1, with a 8·8314(6), b 17·834(2), c 20·001(2) Å, α 115·249(7), β 90·930(7), γ 94·082(7)˚, Z 4, 4724 unique reflections (703 parameters), converging at R 0·035 and Rw 0·034. Despite the [ligated metal donor]-bridge-[nitro acceptor] composition of these complexes, Au–C and C≡C distances are normal and consistent with minimal allenylidene contribution to the ground-state geometry. Within the 3σ confidence limits, the structural data do not provide evidence for π*-back-bonding in these complexes

Synthesis, in vitro inhibition effect of novel phthalocyanine complexes as carbonic anhydrase and paraoxonase enzyme inhibitors

2020 ◽  
Vol 24 (08) ◽  
pp. 1047-1053
Author(s):  
Emre Güzel ◽  
Barış Seçkin Arslan ◽  
Kübra Çıkrıkçı ◽  
Adem Ergün ◽  
Nahit Gençer ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Enzyme Inhibitors ◽  
Inhibition Effect ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
First Time ◽  
Ft Ir Spectroscopy ◽  
C Nmr

The preparation and assessment of carbonic anhydrase and paraoxonase enzyme inhibition properties of 3-(2-(5-amino-4-(4-bromophenyl)-3-methyl-1H-pyrazol-1-yl)ethoxy)phthalonitrile (2) and its nitrogen-containing non-peripheral phthalocyanine derivatives (3 and 4) are reported for the first time. The new phthalonitrile and its phthalocyanine derivatives have been elucidated by FT-IR spectroscopy, 1H-NMR, [Formula: see text]C-NMR, mass and UV-vis spectroscopy. The results demonstrated that all synthesized compounds moderately inhibited carbonic anhydrase and paraoxonase enzymes. Among the compounds, the most active ones were found to be compound 4 for PON (Ki : 0.14 [Formula: see text]M), compound 3 for hCA I (Ki : 22.52 [Formula: see text]M) and compound 1 for hCA II (Ki : 13.62 [Formula: see text]M).

Boron Carbide B25C and B8C18 Synthesized Using Boric Acid-Glucose and Boric Acid-Active Carbon at Low Temperature without Coreductor Materials

2014 ◽  
Vol 896 ◽  
pp. 609-612 ◽  
Author(s):  
Mufirah Cahya Fajrah Toana ◽  
Bambang Soegijono
Keyword(s):  
Boron Carbide ◽  
Boric Acid ◽  
Diffraction Pattern ◽  
Active Carbon ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Space Group ◽  
X Ray ◽  
Crystal System

This study examines the formation of Boron carbide with a wide homogeneity range B8C18 and B25C, from boric acid-glucose and boric acid-active carbon as precursor materials. The samples was analysed by means of X-ray diffraction and Fourier Transform Infrared spectrometer. X-ray diffraction pattern was analysed by GSAS software. X ray diffraction pattern of B8C18 shows peaks at 27o, 39o, 45o, 65o and 79o, orthorhombic crystal system and lattice parameters a = 13.640 Ǻ, b = 7.8500 Ǻ and c = 12.910 Ǻ and space group P212121, whereas for B25C sample show peaks at 2θ angle 28o and 40o, tetragonal crystal system, and the lattice parameters a = b = 8.753 Ǻ and c = 5.093 Ǻ and space group P-4 2 m. FTIR results show that for B8C18 have absorption bands with B-C bond at 1196.5 cm-1, 0-H 3216.7 cm-1 and B-O at 1477.1 cm-1, whereas the formation B25C have absorption bands with B-C bond at 1195.1 cm-1, O-H 3216.7 cm-1 and B-O 1460.8 cm-1.

X-ray diffraction data of Ti2O2(C2O4)(OH)2·H2O

1994 ◽  
Vol 9 (3) ◽  
pp. 187-188 ◽  
Author(s):  
Hee-Lack Choi ◽  
Naoya Enomoto ◽  
Nobuo Ishizawa ◽  
Zenbe-e Nakagawa
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder diffraction data for Ti2O2(C2O4)(OH)2·H2O were obtained. The crystal system was determined to be orthorhombic with space group C2221. The unit cell parameters were refined to a = 1.0503(2) nm, b = 1.5509(3) nm, and c = 0.9700(1) nm.

Crystal and molecular structure of Z- and E-1,2-dichloro-1,2-bis(2-chlorophenyl)ethylene. An X-ray and NMR study

1995 ◽  
Vol 73 (9) ◽  
pp. 1520-1525
Author(s):  
Luciano Antolini ◽  
Ugo Folli ◽  
Dario Iarossi ◽  
Adele Mucci ◽  
Silvia Sbardellati ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Nmr Study ◽  
Phenyl Rings ◽  
A Cell ◽  
C Nmr

The crystal structures of the title compounds were determined by single crystal X-ray diffraction techniques. The molecule of the Z isomer, which crystallizes in the monoclinic space group C2/c with Z = 4 in a cell of dimensions a = 14.891 (2), b = 10.780(2), c = 8.769(1) Å, β = 97.47(2)°, V = 1395.7(7) Å3 has crystallographic twofold symmetry. The E form crystallizes in the orthorhombic space group Pbca with a = 11.730(1), b = 6.932(1), c = 16.841(1) Å, V = 1369.4(2) Å3 and Z = 4. Its molecules have crystallographically dictated [Formula: see text] symmetry. In both isomers the phenyl rings are roughly perpendicular to the average ethylene plane. The atoms characterizing this plane show significant deviations from planarity in the Z isomer. Marked bond-angle distortions at the ethene carbons of both structures are observed. The 1H and 13C NMR spectra of the compounds were measured and, particularly in the case of the 1H chemical shifts, fall into two quite separate spectral regions. At low temperature, two conformational isomers, those with different relative orientation of the C—Cl bonds of the phenyl rings, are observed in the spectrum of each compound. Keywords: chlorostilbenes, overcrowded molecules. X-ray structure, conformations, NMR spectroscopy.

Darstellung und Struktur von Dimesitylzinnoxid / Synthesis and Structure of Dimesityltinoxide

1982 ◽  
Vol 37 (10) ◽  
pp. 1316-1321 ◽  
Author(s):  
U. Weber ◽  
N. Pauls ◽  
W. Winter ◽  
H. B. Stegmann
Keyword(s):  
Mass Spectroscopy ◽  
Aqueous Ammonia ◽  
Asymmetric Unit ◽  
Space Group ◽  
X Ray ◽  
R Factor ◽  
Twist Conformation ◽  
Oxygen Heterocycles ◽  
C Nmr

Abstract Trimesityltin bromide reacts with concentrated aqueous ammonia to give trimesityltin hydroxide. This compound eliminates mesitylen and yields dimesityltin oxide. The product was investigated bv 13C NMR, mass spectroscopy and X-ray diffractions. Di-mesityltinoxide crystallizes in the space group P21/w with a = 25.38(1) Å, b = 12.525(5) Å, c= 32.91(1) Å, β= 91.37(3)° and two molecules in the asymmetric unit (Z=8). The R-factor is 0.049 for 4688 symmetry-independent reflections. The trimeric molecules have six-membered tin-oxygen heterocycles in a twist conformation.

Effect of (La0.67Ca0.33MnO3)x (x = 0.0 – 0.6) Addition in YBa2Cu3O7-δ System on the Structure and Transport Properties

2012 ◽  
Vol 501 ◽  
pp. 314-318
Author(s):  
B.N. Fadilah ◽  
S.A. Halim ◽  
M. Hashim
Keyword(s):  
Transition Temperature ◽  
Transport Properties ◽  
Xrd Analysis ◽  
Magnetic Behaviour ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Space Group ◽  
Crystal System ◽  
Average Grain Size

The effect of LCMO addition in YBCO system to investigate changes in structure and transport properties is reported. Samples with addition of (La0.67Ca0.33MnO3)x (LCMO) (x=0.0-0.6) in YBa2Cu3O7-δ(YBCO) superconducting system were prepared via solid state reaction. The effect of magneto resistive components on the superconducting properties of YBCO was investigated through X-Ray diffraction (XRD), resistance-temperature (R-T) measurement, and Scanning Electron Microscope (SEM). XRD analysis showed the addition of LCMO (0.2 wt% - 0.6 wt%) formed four new phases. The crystal system still orthorhombic with space group Pmmm after addition 0.2 wt% and 0.4 wt% of LCMO but the crystal system was changed to tetragonal and space group P4/mmm when addition with 0.6 wt% of LCMO. The temperature dependent of electrical resistance showed the samples were metallic above the transition temperature even though after addition. TheTc(onset)superconducting transition temperature decreased from 84 K to 66 K while theTc (offset)decreased from 72°C to 54°C. This suppression was due to the magnetic behaviour of the LCMO. The average grain size decreased when addition with LCMO were increased.

Characterization of the unusual metal-free, zinc, chloroindium, and ferrocenylindium 5,10,15,20-tetraferrocenylporphyrin anion-radicals by spectroelectrochemical, DFT, and TDDFT approaches

2012 ◽  
Vol 16 (07n08) ◽  
pp. 793-801 ◽  
Author(s):  
Victor N. Nemykin ◽  
Ping Chen ◽  
Pavlo V. Solntsev ◽  
Anatolii A. Purchel ◽  
Karl M. Kadish
Keyword(s):  
Density Functional ◽  
Broad Band ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Additional Information ◽  
Vis Spectroscopy ◽  
Controlled Potential ◽  
First Time ◽  
Anion Radicals

Anion-radicals of general formula [MTFcP]- ( M = 2H, Zn, InCl , and InFc; TFcP2- is a dianion of 5,10,15,20-tetraferrocenylporphyrin) were prepared for the first time in situ by controlled potential reduction of the respective neutral MTFcP complexes in a thin layer spectroelectrochemical cell. UV-vis spectroscopy reveals the formation of a broad NIR band between 827–890 nm and another broad band in the Soret region between 458 and 527 nm. A similar NIR band has previously been assigned to 5,10,15,20-tetra(aryl)porphyrin radical-anions. Additional information on the electronic structure and nature of the vertical excitation energies in the [H2TFcP]- system were obtained by density functional theory (DFT) and time-dependent DFT (TDDFT) methods. DFT calculations predict that the SOMO in the [H2TFcP]- anion-radical is predominantly localized over the porphyrin core. TDDFT calculations suggest numerous MLCT transitions in addition to the expected π–π* excitations, which play a key role in the formation of unusual UV-vis spectra in the [MTFcP]- anion-radicals.

Sign in / Sign up

Export Citation Format

Share Document