scholarly journals Group 11 Pincer Oxazoline Complexes

2021 ◽  
Author(s):  
Mahroo T. Seighalani
Keyword(s):  
Point Group ◽  
Diffraction Method ◽  
Binding Mode ◽  
Group Symmetry ◽  
Pincer Complexes ◽  
Pincer Ligands ◽  
Henry Reaction ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Nitroaldol Reaction

The synthesis and characterization of new copper pincer complexes via cyclometallation of potentially anionic pincer ligands with C1 point group symmetry is reported. All of these complexes have been characterized by single crystal X-ray diffraction method, which confirms the proposed tridentate binding mode of pincer ligand and the formation of an amido N-Cu bond. The reactivity of two of the complexes was investigated towards C-C bond formation reaction, notably the Henry reaction. One of the complexes, which was derived from the achiral pincer ligand, is shown to be a suitable catalyst for the Henry reaction under the standard conditions. The Henry or nitroaldol reaction is one of the organic reactions which affords a C-C bond. The product of this reaction is a β-nitro alcohol which is formed by addition of a nitroalkane to a carbonyl compound.

scholarly journals Group 11 Pincer Oxazoline Complexes

2021 ◽  
Author(s):  
Mahroo T. Seighalani
Keyword(s):  
Point Group ◽  
Diffraction Method ◽  
Binding Mode ◽  
Group Symmetry ◽  
Pincer Complexes ◽  
Pincer Ligands ◽  
Henry Reaction ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Nitroaldol Reaction

The synthesis and characterization of new copper pincer complexes via cyclometallation of potentially anionic pincer ligands with C1 point group symmetry is reported. All of these complexes have been characterized by single crystal X-ray diffraction method, which confirms the proposed tridentate binding mode of pincer ligand and the formation of an amido N-Cu bond. The reactivity of two of the complexes was investigated towards C-C bond formation reaction, notably the Henry reaction. One of the complexes, which was derived from the achiral pincer ligand, is shown to be a suitable catalyst for the Henry reaction under the standard conditions. The Henry or nitroaldol reaction is one of the organic reactions which affords a C-C bond. The product of this reaction is a β-nitro alcohol which is formed by addition of a nitroalkane to a carbonyl compound.

scholarly journals Formazanate Complexes of Bis-Cyclometalated Iridium

2019 ◽  
Author(s):  
Evanta Kabir ◽  
Ge Mu ◽  
David A. Momtaz ◽  
Noah A. Bryce ◽  
Thomas Teets
Keyword(s):  
Point Group ◽  
Binding Mode ◽  
Group Symmetry ◽  
Binding Modes ◽  
X Ray Diffraction ◽  
Substitution Pattern ◽  
X Ray ◽  
Redox Active ◽  
Symmetric Geometry ◽  
New Compounds

<div>In this work we describe a series of bis-cyclometalated iridium(III) formazanate complexes, expanding the coordination chemistry of the redox-active formazanate class to iridium. A total of 18 new complexes are described, varying the substituent pattern on the formazanate and the identity of the cyclometalating ligand on iridium. Eight of the new compounds are structurally characterized by single-crystal X-ray diffraction, which along with NMR spectroscopy evinces two binding modes of the formazanate. Two of the compounds are isolated in a C2-symmetric geometry where the formazanate is bound in a six-member chelate “closed” conformation, involving the 1- and 5-positions of the 1,2,4,5-tetraazapentadienyl formazanate core. In most of the examples, the major isomer that forms and is exclusively isolated involves the formazanate bound in a five-member chelate “open” form, coordinating through the 1- and 4-positions of the formazanate core and resulting in C1 point-group symmetry. All complexes are characterized by UV-vis absorption spectroscopy and cyclic voltammetry, with these features depending primarily on the substitution pattern on the formazanate, and to a lesser extent on the identity of the cyclometalating ligand and formazanate binding mode.</div>

Formazanate Complexes of Bis-Cyclometalated Iridium

2019 ◽  
Author(s):  
Evanta Kabir ◽  
Ge Mu ◽  
David A. Momtaz ◽  
Noah A. Bryce ◽  
Thomas Teets
Keyword(s):  
Point Group ◽  
Binding Mode ◽  
Group Symmetry ◽  
Binding Modes ◽  
X Ray Diffraction ◽  
Substitution Pattern ◽  
X Ray ◽  
Redox Active ◽  
Symmetric Geometry ◽  
New Compounds

<div>In this work we describe a series of bis-cyclometalated iridium(III) formazanate complexes, expanding the coordination chemistry of the redox-active formazanate class to iridium. A total of 18 new complexes are described, varying the substituent pattern on the formazanate and the identity of the cyclometalating ligand on iridium. Eight of the new compounds are structurally characterized by single-crystal X-ray diffraction, which along with NMR spectroscopy evinces two binding modes of the formazanate. Two of the compounds are isolated in a C2-symmetric geometry where the formazanate is bound in a six-member chelate “closed” conformation, involving the 1- and 5-positions of the 1,2,4,5-tetraazapentadienyl formazanate core. In most of the examples, the major isomer that forms and is exclusively isolated involves the formazanate bound in a five-member chelate “open” form, coordinating through the 1- and 4-positions of the formazanate core and resulting in C1 point-group symmetry. All complexes are characterized by UV-vis absorption spectroscopy and cyclic voltammetry, with these features depending primarily on the substitution pattern on the formazanate, and to a lesser extent on the identity of the cyclometalating ligand and formazanate binding mode.</div>

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

Structural Investigations of Colloidal Semiconductor Nanocrystal Heterostructures: Faceting and Epitaxy

1996 ◽  
Vol 452 ◽  
Author(s):  
A. V. Kadavanich ◽  
A. Mews ◽  
S. H. Tolbert ◽  
X. Peng ◽  
M. C. Schlamp ◽  
...  
Keyword(s):  
Point Group ◽  
Group Symmetry ◽  
X Ray Diffraction ◽  
Structural Investigations ◽  
Transmission Microscopy ◽  
Cds Quantum Dot ◽  
Show Evidence ◽  
Multi Wavelength ◽  
Heterogeneous Phase ◽  
Phase Proceeds

AbstractWe use High Resolution Transmission Microscopy (HRTEM) to study CdSe, CdS/HgS/CdS quantum-dot quantum well (QDQW), and CdSe/CdS core-shell nanocrystals, grown by wet-chemical techniques. The nanocrystals have faceted Wulff polyhedron shapes.In addition to HRTEM, we employ multi-wavelength anomalous dispersion (MAD) x-ray diffraction. We use computer modeling to help interpret the experimental data.Growth of a heterogeneous phase proceeds epitaxially preserving the overall shape and point-group symmetry of the original seed nanocrystals, both for wurtzite (CdSe/CdS) and zincblende (CdS/HgS/CdS) type structures.Recently prepared InAs nanocrystals also show evidence of faceting as observed by HRTEM and may lend themselves equally well to epitaxy.

scholarly journals Darstellung und Kristallstruktur von [(NH3)5Rh(H7O4)Rh(NH3)5](S2O6)2,5 · H2O (1). Ein gemischtes Aquopentamminrhodium(III)-hydroxopentamminrhodium(III)- dithionat mit einer neuartigen μ-H7O4-Struktureinheit / Preparation and Crystal Structure of [(NH3)5Rh(H7O4)Rh(NH3)5](S2O6)2,5 · H2O (1). A Mixed Aquopentaamminerhodium(III)-hydroxopentaamminerhodium(III) Dithionate with a Novel μ-H7O4 Structural Unit

1988 ◽  
Vol 43 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Walter Frank ◽  
Thomas Stetzer ◽  
Ludwig Heck
Keyword(s):  
Crystal Structure ◽  
Structural Unit ◽  
Small Difference ◽  
Point Group ◽  
Group Symmetry ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray

The title compound 1 can be obtained from an aqueous solution of aquopentaammine rhodium(III) dithionate and hydroxopentaammine rhodium(III) dithionate. The crystal structure has been determined from single crystal X-ray diffraction data and refined to R = 0.035 for 4390 unique reflections. Crystal data: monoclinic, space group P21/c, a = 1300.9(5) pm. b = 1472.3(6) pm. c = 1478.8(9) pm, β = 106.20(4)°, Z = 4.In the crystal dinuclear rhodium cations with point group symmetry 1 (C1) are found. A central μ-H3O2-bridge is formed by strong hydrogen bonding between aquo and hydroxo ligands; this bridge is additionally coordinated by two molecules of water. The entire bridging system is therefore H7O4-(H3O2- · 2 H2O). O-O distances characterizing the strength of the three hydrogen bonds within this new kind of structural unit are O(H2O-Rh 1)-O(HO-Rh2): 248 pm. O(H2O-Rh 1)-O(H2Oa): 273 pm, O(HO-Rh2)-O(H2Ob): 287 pm. The hydrogen atoms involved in these bridges have been located. The small difference in the Rh 1-O(H2O) - (205.4(3) pm) and Rh2-O(OH)- (204.3(3) pm) distances indicates that the entire H7O4-- moiety serves as a μ-bridging unit between Rh 1 and Rh 2

scholarly journals Redetermination of the crystal structure of caesium tetrafluoridobromate(III) from single-crystal X-ray diffraction data

IUCrData ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Artem V. Malin ◽  
Sergei I. Ivlev ◽  
Roman V. Ostvald ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Point Group ◽  
Group Symmetry ◽  
Site Symmetry ◽  
X Ray Diffraction ◽  
Cation Site ◽  
X Ray ◽  
Square Planar

Caesium tetrafluoridobromate(III), CsBrF4, was crystallized in form of small blocks by melting and recrystallization. The crystal structure of CsBrF4 was redetermined from single-crystal X-ray diffraction data. In comparison with a previous study based on powder X-ray diffraction data [Ivlev et al. (2013). Z. Anorg. Allg. Chem. 639, 2846–2850], bond lengths and angles were determined with higher precision, and all atoms were refined with anisotropic displacement parameters. It was confirmed that the structure of CsBrF4 contains two square-planar [BrF4]− anions each with point group symmetry mmm, and a caesium cation (site symmetry mm2) that is coordinated by twelve fluorine atoms, forming an anticuboctahedron. CsBrF4 is isotypic with CsAuF4.

scholarly journals catena-Poly[barium(II)-μ2-(dimethyl sulfoxide)-κ2 O:O-bis(μ2-2,4,6-trinitrophenolato-κ4 O 2,O 1:O 1,O 6)]

IUCrData ◽  
2020 ◽  
Vol 5 (11) ◽  
Author(s):  
Bikshandarkoil R. Srinivasan ◽  
Neha U. Parsekar ◽  
Kedar U. Narvekar
Keyword(s):  
Coordination Polymer ◽  
Oxygen Atom ◽  
Dimethyl Sulfoxide ◽  
Point Group ◽  
Binding Mode ◽  
Group Symmetry ◽  
Site Symmetry ◽  
Cation Site ◽  
A Chain ◽  
The One

The asymmetric unit of the title barium coordination polymer, [Ba(C6H2N3O7)2(C2H6OS)] n , consists of a barium cation (site symmetry m) and a dimethyl sulfoxide (DMSO) ligand (point group symmetry m) and a 2,4,6-trinitrophenolate anion located in general positions. The S atom and the methyl group of DMSO are disordered over two sets of sites. The DMSO ligand bridges a pair of BaII atoms resulting in a chain extending parallel to the a axis. The unique 2,4,6-trinitrophenolate anion also bridges a pair of BaII ions via the phenolic oxygen atom, with each BaII being additionally bonded to an oxygen atom of an adjacent nitro group. The μ 2-monoatomic bridging binding mode of both types of ligands results in the formation of an infinite chain of face-sharing {BaO10} polyhedra flanked by the remaining parts of the 2,4,6-trinitrophenolato and DMSO ligands. In the one-dimensional coordination polymer, parallel chains are interlinked with the aid of C—H...O hydrogen bonds.

scholarly journals Phase transition sequences in tetramethylammonium tetrachlorometallates by X-ray diffraction and spectroscopic measurements

2017 ◽  
Vol 73 (5) ◽  
pp. 844-855 ◽  
Author(s):  
Jack Binns ◽  
Garry J McIntyre ◽  
José A. Barreda-Argüeso ◽  
Jesús González ◽  
Fernando Aguado ◽  
...  
Keyword(s):  
Phase Transition ◽  
Point Group ◽  
Lone Pair ◽  
Group Symmetry ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Intermediate Phases ◽  
Increasing Temperature ◽  
First Time ◽  
Prototype Phase

The phase transition sequences of two members of the tetramethylammonium tetrachlorometallate(III) family of hybrid organic–inorganic salts have been determined and structurally characterized as a function of temperature for the first time. Unusually, a reduction in point-group symmetry with increasing temperature until reaching a cubic prototype phase is observed. Two additional intermediate phases are observed for Fe3+. First-principles calculations and the presence of short Cl...Cl contacts for Ga3+suggest the [GaCl4]−anion to be conformationally hindered due to stronger lone-pair–σ-hole interactions. The conformationally more flexible Fe3+structures show sublattice melting with the onset of rotational disorder in the [NMe4]+cations occurring 40 K below the corresponding onset of rotational disorder in the [FeCl4]−sublattice.

Oxazoline chemistry. Part VIII. Synthesis and characterization of a new class of pincer ligands derived from the 2-(o-anilinyl)-2-oxazoline skeleton — Applications to the synthesis of group X transition metal catalysts

2005 ◽  
Vol 83 (8) ◽  
pp. 1185-1189 ◽  
Author(s):  
Andreas Decken ◽  
Robert A Gossage ◽  
Paras N Yadav
Keyword(s):  
Heck Reaction ◽  
Picolinic Acid ◽  
Point Group ◽  
Binding Mode ◽  
Transition Metal Catalysts ◽  
Synthesis And Characterization ◽  
Pincer Ligands ◽  
Bond Forming ◽  
Pd Complexes

The synthesis and characterization of a new and readily synthesized class of potentially anionic pincer ligands with C1 point group symmetries is described. These materials can be made via amide coupling of a 2-(2′-anilinyl)-2-oxazoline unit with picolinic acid; the incorporation of enantiopure oxazoline fragments facilitates the construction of chiral C1 pincers. Treatment of the free ligands with Pd metal sources leads to the formation of amido–Pd pincer complexes in good yield. One of these Pd complexes has been characterized by single crystal X-ray diffraction methods, which confirms the proposed tridentate binding mode of the ligand and the formation of an amido N—Pd bond. The metal complexes have been shown to be suitable precusors for catalytically active Pd species that are useful for C—C bond forming reactions, notably the Heck reaction under standard conditions. Key words: oxazoline, 4,5-dihydro-2-oxazole, palladium, pincer ligand, amido, Heck reaction.

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