Backbone Phosphonamide-Functionalized Imidazol-2-ylidene Complexes

2016 ◽  
Vol 69 (10) ◽  
pp. 1186
Author(s):  
Paresh Kumar Majhi ◽  
Gregor Schnakenburg ◽  
Anthony J. Arduengo ◽  
Rainer Streubel
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
X Ray ◽  
Structure Determinations

The synthesis of M(CO)5 complexes bearing 4-phosphonamide and 4,5-bis(phosphonamide)-imidazol-2-ylidene ligands (NHCP = phosphonamide-based N-heterocyclic carbene) is reported. Deprotonation of respective imidazolium hydrogensulfate salts with potassium tert-butoxide (KOtBu) in the presence of [M(CO)5(CH3CN)] afforded complexes with the formula [M(CO)5(NHCP)]. In a similar fashion, reaction of in situ generated NHCP with [Rh(cod)Cl]2 (cod = 1,5-cyclooctadiene) afforded a complex with the formula [Rh(cod)Cl(NHCP)]. Low-temperature deprotonation of the imidazolium NHCP·H2SO4 with potassium hexamethyldisilazide (KHMDS) in the presence of [AuCl(SMe2)] furnished the corresponding AuI NHC complex. All complexes were characterized by various spectroscopic and spectrometric methods. In addition, further structural confirmation is provided by key single-crystal X-ray structure determinations for three of the new complexes.

Structural Systematics of Rare Earth Complexes. XXII. ('Maximally') Hydrated Rare Earth Iodides

2000 ◽  
Vol 53 (10) ◽  
pp. 867 ◽  
Author(s):  
Kevin C. Lim ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Low Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Second Phase ◽  
X Ray ◽  
Structure Determinations ◽  
Trivalent Rare Earth ◽  
Trigonal Prismatic

Low-temperature (c. 153 K) single-crystal X-ray structure determinations, carried out on trivalent rare earth iodides crystallized from aqueous solution at room temperature, have defined two series of hydrates, LnI3.nH2O. For Ln = La–Ho, a nonahydrate phase (n = 9) is defined, orthorhombic Pmmn, a ~ 11.5, b ~ 8.0, c ~ 8.8 Å, Z = 2, the second phase (n = 10), monoclinic P21/c, Z = 4 being defined for Ln = Er–Lu, a ~ 8.2, b ~ 12.8, c ~ 17.1 Å, β ~ 103.7˚. Neither of these phases is isomorphous with any of those pertinent to the previously studied chloride or bromide (hydrated) arrays, nor, unlike those, does the halide (iodide) in any case enter the coordination sphere of the lanthanoid. The n = 9 phase takes the form [Ln(OH2)9]I3, the nine-coordinate lanthanoid environment stereochemistry being tricapped trigonal-prismatic, while the n = 10 phase is [Ln(OH2)8]I3.2H2O, the eight-coordinate lanthanoid environment being square-antiprismatic.

Crystal Structures of the ('Maximally') Hydrated Scandium Halides, ScX3.nH2O (X = Cl, Br, I)

2000 ◽  
Vol 53 (10) ◽  
pp. 875 ◽  
Author(s):  
Kevin C. Lim ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Low Temperature ◽  
Water Molecule ◽  
Single Crystal ◽  
Crystal Structures ◽  
Metal Atom ◽  
Coordination Sphere ◽  
Monoclinic Space Group ◽  
Site Symmetry ◽  
X Ray ◽  
Structure Determinations

Low-temperature single-crystal X-ray structure determinations are recorded for the (‘maximally’) hydrated scandium(III) trihalides, ScX3.nH2O (X = Cl, Br, I). The chloride and bromide are isomorphous heptahydrates (n =7), ScX3.7H2O =[Sc(OH2)7]X3, monoclinic, space group P2/n, a ~ 7.6, b ~ 7.7, c ~ 9.6 Å, β ~ 99˚, Z = 2, R 0.051, 0.039 for No 1253, 1339 ‘observed’ (F > 4σ (F)) reflections, respectively, the metal atom disposed in a homoleptic environment of seven water molecule oxygen atoms arranged in an essentially pentagonal-bipyramidal disposition, site symmetry 2, Sc–O(axial) 2.095 Å, Sc–O(eq) 2.157(3)–2.209(4) Å. The iodide is an octahydrate, ScI3.8H2O =[Sc(OH2)7]I3.H2O, monoclinic P21/c, Z = 4, R 0.022 for No 3243; the seven-coordinate metal atom environment here is well distorted from the pentagonal-bipyramidal norm, the largest angle in the coordination sphere being 162.4(1)˚, subtended by Sc–O 2.109(3), 2.128(3) Å, the remaining Sc–O ranging between 2.157(3)–2.219(3) Å.

The low-temperature behaviour of cancrinite:an in situ single-crystal X-ray diffraction study

2012 ◽  
Vol 76 (4) ◽  
pp. 933-948 ◽  
Author(s):  
G. Diego Gatta ◽  
P. Lotti ◽  
V. Kahlenberg ◽  
U. Haefeker
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Structure Refinement ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Structural Behaviour ◽  
X Ray ◽  
Positional Disorder ◽  
Deformation Processes

AbstractThe low-temperature structural behaviour of natural cancrinite with a formula Na6.59Ca0.93[Si6.12Al5.88O24](CO3)1.04F0.41·2H2O has been investigated by means of in situ single-crystal X-ray diffraction and Raman spectroscopy. High quality structure refinements were obtained at 293, 250, 220, 180, 140, 100 and at 293 K again (at the end of the low-T experiments). The variation in the unit-cell volume as a function of temperature (T) exhibits a continuous trend, without any evident thermoelastic anomaly. The thermal expansion coefficient αV = (1/V)∂V/∂T is 3.8(7) × 10–5 K–1 (between 100 and 293 K). The structure refinement based on intensity data collected at ambient conditions after the low-T experiment confirmed that the low-T induced deformation processes are completely reversible. The extraframework population does not show significant variations down to 100 K. The strong positional disorder of the carbonate groups along the c axis persists within the T range investigated. The structural behaviour of cancrinite at low-T is mainly governed by the continuous framework rearrangement through the ditrigonalization of the six-membered rings which lie in a plane perpendicular to [0001], the contraction of the four-membered ring joint units, the decrease of the ring corrugation in the (0001) plane, and the flattening of the cancrinite cages. A list of the principal Raman active modes in ambient conditions is provided and discussed.

Low-temperature and high-pressure polymorphs of isopropyl alcohol

CrystEngComm ◽  
2014 ◽  
Vol 16 (32) ◽  
pp. 7397-7400 ◽  
Author(s):  
Joe Ridout ◽  
Michael R. Probert
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Single Crystal ◽  
Isopropyl Alcohol ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray

Single-crystal X-ray diffraction has been used to elucidate the structure of two polymorphs of isopropyl alcohol, one grown through in situ cryo-crystallisation, the other through high-pressure crystallisation.

The structure of chloromethyl thiocyanate, CH2ClSCN, in gas and crystalline phases

2015 ◽  
Vol 17 (24) ◽  
pp. 15805-15812 ◽  
Author(s):  
Y. Berrueta Martínez ◽  
L. S. Rodríguez Pirani ◽  
M. F. Erben ◽  
C. G. Reuter ◽  
Y. V. Vishnevskiy ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Low Temperature ◽  
Single Crystal ◽  
Gas Phase ◽  
Solid Phase ◽  
Gas Electron Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conformational Properties

The structural and conformational properties of chloromethyl thiocyanate, CH2ClSCN, were studied in the solid phase and in the gas phase usingin situlow-temperature single-crystal X-ray diffraction experiments (XRD) and gas electron diffraction (GED), respectively.

scholarly journals Low-Temperature Crystal Chemistry of Hingganite-(Y), from the Wanni Glacier, Switzerland

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 322 ◽  
Author(s):  
Liudmila Gorelova ◽  
Oleg Vereshchagin ◽  
Stéphane Cuchet ◽  
Vladimir Shilovskikh ◽  
Dmitrii Pankin
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Single Crystal ◽  
Layer Plane ◽  
X Ray Diffraction ◽  
Wavelength Dispersive Spectroscopy ◽  
X Ray ◽  
Thermal Expansion Anisotropy ◽  
High Thermal Expansion

Hingganite from the Wanni glacier (Switzerland) was studied by means of energy dispersive and wavelength-dispersive spectroscopy, Raman spectroscopy, and low-temperature single-crystal X-ray diffraction. According to its chemical composition, the investigated mineral should be considered as hingganite-(Y). It showed a relatively high content of Gd, Dy, and Er and had limited content of lighter rare-earth element (REE), which is typical for Alpine gadolinite group minerals. The most intense Raman bands were 116, 186, 268, 328, 423, 541, 584, 725, 923, 983, 3383, and 3541 cm−1. Based on data of low-temperature [(−173)–(+7) °C] in situ single-crystal X-ray diffraction, it was shown that the hingganite-(Y) crystal structure was stable in the studied temperature range and no phase transitions occurred. Hingganite-(Y) demonstrated low volumetric thermal expansion (αV = 9(2) × 10−6 °C−1) and had a high thermal expansion anisotropy up to compression along one of the directions in the layer plane. Such behavior is caused by the shear deformations of its monoclinic unit cell.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

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