Cage Precursor Ligands: A Sexidentate Triamine Trioxime and Its Complexes With Cobalt(III)

1990 ◽  
Vol 43 (11) ◽  
pp. 1803 ◽  
Author(s):  
LM Engelhardt ◽  
JM Harrowfield ◽  
SJ Mcniven ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Structure Determination ◽  
Complex Cation ◽  
Cobalt Complex ◽  
Side Reaction ◽  
Chloride Anion ◽  
X Ray ◽  
Nitrogen Donor ◽  
Deep Yellow ◽  
A Minor ◽  
Hydroxyl Protons

The ligand ' tamox ' (CH3C{CH2NHC(CH3)2C(CH3)=NOH}3) has been synthesized from 1,1,1-tris ( aminomethyl )ethane and 2-chloro-2-methyl-3-nitrosobutane. The ligand forms a deep yellow cobalt(III) complex which crystallizes readily from acidic solution as a monohydrated chloride diperchlorate salt. An X-ray structure determination on the monoclinic crystals, space group P21/c, a 10.254(4), b 22.30(1), c 15.375(8) Ǻ, β 117.16(4)°, Z 4, was refined to conventional R= 0.048 for 4573 'observed' reflections. The ligand is sexidentate with distinctly different bonding interactions of the two types of nitrogen-donor atoms ({Co- Namine } 1.97, {Co- Noxime } 1.92 Ǻ). The chloride anion interacts strongly with the complex cation through symmetrical hydrogen bonding to all three oxime hydroxyl protons. From neutral solution, the complex can be crystallized as an approximately trihydrated dichloride, the ligand having lost one proton ( pKa ≈ 3, I= 1.0, at 298 K). An X-ray structure determination for these crystals, monoclinic, P21/c, a 12.565(3), b 14.686(12), c 18.524(16) Ǻ, β 123.88(2)°, Z 4, R 0.054 for 3900 'observed' reflections, shows that neither chloride anion has any special mode of association with the cation. Attempts to 'cap' the [Co( tamox )]3+ complex by reactions with aqueous borate and phenyl boronate were unsuccessful. There is apparently a minor side reaction in the formation of the cobalt complex, a reaction which leads to the hydrolysis of one of the oxime groups of the ligand and the generation of a trans- dichlorocobalt (III) complex of this hydrolysed ligand in a quadridentate form. The nature of this green material has been established by an X-ray structure determination of its perchlorate salt, monoclinic, P21/c, a 14.38(2), b 18.20(1), c 14.71(2)Ǻ, β 118.80(7)°, Z 4, R 0.070 for 2120 'observed' reflections.

An assessment of oxime-oximato hydrogen bonding: A structural and thermodynamic study of copper(II) complexes

1978 ◽  
Vol 31 (4) ◽  
pp. 723 ◽  
Author(s):  
EA Daniel ◽  
FC March ◽  
HKJ Powell ◽  
WT Robinson ◽  
JM Russell
Keyword(s):  
Hydrogen Bonding ◽  
Methyl Ether ◽  
Complex Cation ◽  
Steric Effects ◽  
Apical Position ◽  
X Ray ◽  
Methyl Substitution ◽  
Perchlorate Ion ◽  
Nitrogen Donor ◽  
The Stability

Copper(II) complexes formed by the diamine dioxime ligand 4,4,9,9- tetramethyl-5,8-diazadodecane-2,11-dione dioxime (H2dddo) and its O-methyl ether (Hddmo) and bis-O-methyl ether (dddm) have been studied. The log K (potentiometric) and ΔH (calorimetric) values are reported for formation of the four-coordinate complexes [Cu(Hddmo)]2+ and [Cu(dddm)]2+ and for the deprotonation of [Cu(Hddmo)]2+ to give [Cu(ddmo)]+ at 25°C, I = 0.1 M NaCl. (log K = 12.11 � 0.04, 9.10�0.02 and -6.76�0.09; ΔH= -43�2, -17.9�0.4 and +21.9�0.9 kJ mol-1 respectively.) Comparison with data for [Cu(H2dddo)]2+ and [Cu(Hdddo)]+ affords information about the relative contributions of (i) oxime deprotonation (c. 105.6), and (ii) oxime oximato hydrogen bonding (c. 103.5), to the stability of these (non-conjugated) dioxime complexes. The formation of intramolecular (oxime-oximato) hydrogen bonds is favoured by a positive ΔS; intermolecular bonds (oximato-solvent) give rise to a negative ΔS. ��� A single-crystal X-ray molecular structure determination is reported for the complex Cu(dddm)-(ClO4)2. In the solid state the complex cation is square pyramidal with one perchlorate ion weakly coordinated in the apical position and the four nitrogen donor atoms forming a distorted square plane about the copper atom. Steric effects associated with O-methyl substitution are assessed. Steric hindrance between adjacent =NOR groups does not increase measurably when =NOH is replaced by =NOMe.

The Anion [Co(C8H12)2]–. A Comparative Study of the Crystal Structures of [{K(18-crown-6)}2(C5H5)][Co(C8H12)2] and Co(C8H12)(C8H13)

2009 ◽  
Vol 64 (8) ◽  
pp. 985-988 ◽  
Author(s):  
Jian-Qiang Wang ◽  
Thomas F. Fässler
Keyword(s):  
Crystal Structure ◽  
Crown Ether ◽  
Comparative Study ◽  
Single Crystal ◽  
Crystal Structures ◽  
Structure Determination ◽  
Cobalt Complex ◽  
Crystal Structure Determination ◽  
X Ray ◽  
Cyclopentadienyl Anion

The cobalt complex [{K(18-crown-6)}2(C5H5)]- [Co(C8H12)2]・(THF)2 (3) has been synthesized and characterized by X-ray single-crystal structure determination. The crystal structure of Co(C8H12)(C8H13) (2) has been reinvestigated and compared with the structure of 3. The 1,5-cyclooctadiene (C8H12) and C8H13 ligands are coordinated in an η4 and η3 fashion, respectively. The cyclopentadienyl anion in [{K(18-crown-6)}2(C5H5)]+ in 3 is η5-coordinated to the two crown ether-encapsulated potassium cations

Methyleneketenes and methylenecarbenes. XVI. The formation of Diphenylfuran-2-ones and 3-Phenylphthalide as minor products of the pyrolysis of diphenylmethyl propiolate

1981 ◽  
Vol 34 (7) ◽  
pp. 1467 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
N Chaichit ◽  
BM Gatehouse ◽  
JM Pfeiffer ◽  
...  
Keyword(s):  
Structure Determination ◽  
Phenyl Ring ◽  
Diels Alder ◽  
Insertion Reaction ◽  
X Ray ◽  
Flash Vacuum Pyrolysis ◽  
Methyl Propiolate ◽  
Vacuum Pyrolysis ◽  
Labelling Experiment ◽  
A Minor

The formation of a mixture of lactones as a minor product of the flash vacuum pyrolysis of diphenyl-methyl propiolate (1) has been investigated further. ��� The diphenylfuran-2-ones (3), (4), and (5) are shown to be formed through an intramolecular insertion reaction of the methylenecarbene (2), formed from (1) at 640°, which leads to 5,5-diphenyl-furan-2(5H)- one (3) as the primary product. ��� 3-Phenylphthalide (8) is apparently formed by intramolecular Diels-Alder addition of the C≡C bond of (1) to one phenyl ring which acts as the diene component, followed by loss of acetylene from an intermediate barrelene derivative (10). This is confirmed by a deuterium labelling experiment. ��� 1-Phenyl-2-benzoxepin-3(1H)-one (7), considered at first as a possible intermediate in the pyrolysis of (1), is synthesized in six steps from 2-aminobenzophenone, and its X-ray structure determination is reported. On pyrolysis at 640°/0.07 mm (7) decarbonylates smoothly to give 2-vinylbenzophenone.

Intramolecular reactions of dialkoxycarbenes with a carbonyl group

2003 ◽  
Vol 81 (6) ◽  
pp. 598-606 ◽  
Author(s):  
Malgorzata Dawid ◽  
John Warkentin
Keyword(s):  
Carbonyl Group ◽  
Side Reaction ◽  
Bimolecular Reaction ◽  
Major Product ◽  
Dipolar Cycloaddition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intramolecular Reactions ◽  
A Minor ◽  
Hydrolysis Of

Thermolysis of 5,5-dimethyl-2-methoxy-2-(2-oxocyclohexylmethoxy)-Δ3-1,3,4-oxadiazoline (3a) in benzene at 110°C generated a carbonyl ylide intermediate that gave, in a minor side reaction, a product of 1,3-dipolar cycloaddition to the carbonyl group. The major fate of the ylide was fragmentation to acetone and a dialkoxycarbene, MeO (RCH2O)C:, where R = 2-oxocyclohexyl. The carbene, in turn, underwent overall [2 + 1] cycloaddition to the carbonyl group, presumably to afford diastereomeric dialkoxyoxiranes that could not be isolated. A product of methanolysis of the presumed oxiranes was isolated by GC and its structure was determined by means of X-ray diffraction. Methanol is believed to result from reaction of an intermediate or product with adventitious water. Deliberate hydrolysis of the product of methanolysis gave a hydroxy lactone, the structure of which was also secured by means of single crystal X-ray diffraction. Those structures indicated the likely structures of the oxirane precursors. A second, and major, product from the carbene was a bicyclic ketone. Similar products were obtained from intramolecular reactions of a carbene tethered to cyclopentanone through a two-carbon or a one-carbon tether. Some compounds that are apparently "dimers" of the oxiranes were also isolated and identified by means of X-ray diffraction. These dimers are thought to originate from the reaction of a ring-opened oxirane (a dipole or a cation from electrophilic opening of the oxirane) with a molecule of the oxirane rather than from bimolecular reaction between two oxirane molecules. The oxiranes open by cleavage of the (RO)2C—O bond rather than the oxirane C—C bond, the normally observed sense of thermal ring opening. The properties of the carbenes and the presumed oxiranes serve to point out the options available to such intermediates and suggest that some new, synthetically useful reactions may become possible.Key words: bicyclic ketone, dialkoxycarbene, dialkoxyoxirane, hydroxylactone, "oxirane dimers".

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

From ensemble average to single (nano-) objects properties by X-ray microdiffraction: a short review on structure determination (local strain, composition, ...) and objects manipulation (AFM-coupled)

2010 ◽  
Vol 107 (10-11) ◽  
pp. 433-439
Author(s):  
C. Mocuta ◽  
K. Mundboth ◽  
J. Stangl ◽  
B. Krause ◽  
A. Malachias ◽  
...  
Keyword(s):  
Structure Determination ◽  
Local Strain ◽  
Short Review ◽  
Ensemble Average ◽  
X Ray
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