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.

Effects of methoxy-substituted metalloporphyrins in catalytic alkene epoxidation by n-Bu4NHSO5

2010 ◽  
Vol 14 (04) ◽  
pp. 335-342 ◽  
Author(s):  
Amineh Aghabali ◽  
Nasser Safari
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic Activity ◽  
High Activity ◽  
Solvent Mixture ◽  
Steric Effects ◽  
Reaction Condition ◽  
Reaction Solution ◽  
Phenyl Rings ◽  
Active Intermediate ◽  
The Stability

TPPMnOAc and four different kinds of manganese tetraphenylporphyrin acetates were synthesized using different numbers of methoxy substituents in various positions of the phenyl rings. These porphyrins were used as catalysts in the epoxidation of various alkenes with tetra-n-butylammonium hydrogen monopersulfate (n- Bu 4 NHSO 5) as the oxidant and imidazole as the axial base. The following order of catalytic activity was obtained: TPPMnOAc ≥ T (2,3- OMeP ) PMnOAc > T (4- OMeP ) PMnOAc > T (3,4- OMeP ) PMnOAc > T (2,4,6- OMeP ) PMnOAc . By studying the UV-vis spectra in the reaction solution, the stability of the applied methoxy porphyrins and the effect of this factor on obtained yields were investigated. Lower catalytic activity in some of the methoxy porphyrins emphasized steric effects and special hydrogen bonding among the reaction elements. However, the stability of T (2,3- OMeP ) PMnOAc under our reaction condition was considerable and high activity was observed. By adding small amounts of alcohol to the reaction solution, the effect of the solvent mixture was previewed and steps were taken to identify the active intermediate of the catalyst in these conditions.

The coordination of β-amino ketoximes with divalent iron, cobalt, nickel and zinc

1978 ◽  
Vol 31 (11) ◽  
pp. 2409 ◽  
Author(s):  
HKJ Powell ◽  
JM Russell
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Stability Constant ◽  
Methyl Ether ◽  
Infrared Spectra ◽  
Iron Cobalt ◽  
Divalent Iron ◽  
Cobalt Nickel ◽  
Stability Order ◽  
The Stability

The iron(II), nickel(II) and zinc(II) complexes of the diamine dioxime ligand 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dioxime (H2dddo) and the cobalt(II), nickel(II) and zinc(II) complexes of its O-methyl ether (Hddmo) have been studied potentiometrically at 25°C, I 0.10M NaCl. Stability constant data are compared with those obtained for the copper(II) and cobalt(II) complexes of H2dddo and the copper(II) complexes of Hddmo. H2dddo coordinates in the oxime-oximato form [M(Hdddo)]+ with iron(II), cobalt(II), nickel(II) and zinc(II) Hddmo forms complexes with the ligand coordinated in the oxime form [M(Hddmo)]2+ and the oximato form [M(ddmo)]+. The complexes [Zn(Hddmo)2]2+, [Zn(Hddmo)(ddmo)]+ and [Co(ddmo)(OH)] were also characterized in aqueous solution. The stability order FeII < CoII < NiII < CuII > ZnII was observed for the formation of 1 : 1 complexes with the ligands Hdddo- (log K = 8.8, 11.7, 15.2, 23.3, 12.0 for Fe to Zn respectively) and Hddmo (5.7, 6.6, 12.1, 5.3 for Co to Zn). The infrared spectra of the complexes [Ni(Hdddo)] ClO4,H2O and [Zn(Hdddo)] ClO4 are discussed in terms of oxime-oximato hydrogen bonding.

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.

scholarly journals Hydrogen bonding-based 3D supramolecular architecture of [Cu(CHA)2][TCM]·11H2O

2014 ◽  
Vol 12 (1) ◽  
pp. 14-24
Author(s):  
Mihaela Vlassa ◽  
Gheorghe Borodi ◽  
Cristian Silvestru ◽  
Mircea Vlassa
Keyword(s):  
Hydrogen Bonding ◽  
Supramolecular Network ◽  
Water Mixture ◽  
Coordination Geometry ◽  
Supramolecular Architecture ◽  
X Ray Diffraction ◽  
Apical Position ◽  
X Ray ◽  
Anionic Ligand ◽  
Carboxylate Groups

AbstractReaction of Na4TCM (1) (H4TCM = tetra[4-(carboxyphenyl)oxamethyl]methane) with [Cu(CHA)](ClO4)2 (2)(CHA = 1,3,6,8,11,14-hexaaz atricyclo[12.2.1.1.8,11] octadecane) in a DMF-water mixture yields [Cu(CHA)]2[TCM] (3). Structural analysis of [Cu(CHA)]2[TCM]·11H2O (3·11H2O) by single crystal X-ray diffraction reveals strong copper-oxygen bonds between two complex cations and the tetraanion leading to a 3D coordination network (zwitterionic structure), consolidated through additional NH...O=C hydrogen bonding within the cation/anion association. The resulting coordination geometry around a copper atom is a distorted square pyramidal with an oxygen atom of the anionic ligand in the apical position. A 3D supramolecular network is developed in the crystal based only on NH...OC hydrogen bonds between the macrocyclic metallic tecton and the carboxylate groups of neighboring 3D coordinated (zwitterionic) moieties. The pseudotetrahedral TCM4− tetraanionic ligand induces a diamondoid architecture formed of large distorted adamantanoid cages.

scholarly journals Design of new anti-Alzheimer drugs: ring-expansion synthesis and synchrotron X-ray diffraction study of dimethyl 4-ethyl-11-fluoro-1,4,5,6,7,8-hexahydroazonino[5,6-b]indole-2,3-dicarboxylate

2018 ◽  
Vol 74 (3) ◽  
pp. 298-301
Author(s):  
Flavien A. A. Toze ◽  
Anna V. Listratova ◽  
Leonid G. Voskressensky ◽  
Natalia Yu. Chernikova ◽  
Nikolai N. Lobanov ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ring Expansion ◽  
Steric Effects ◽  
X Ray Diffraction ◽  
Interplanar Angle ◽  
X Ray ◽  
Compound C ◽  
Hydrogen Bonding Interactions ◽  
Pyramidal Configuration ◽  
Ring Expansion Reaction

The title compound, C20H23FN2O4, is the product of a ring-expansion reaction from a seven-membered fluorinated hexahydroazepine to a nine-membered azonine. The nine-membered azonine ring of the molecule adopts achair–boatconformation. The C=C and C—N bond lengths [1.366 (3) and 1.407 (3) Å, respectively] indicate the presence of conjugation within the enamine CH2—C=C—N—CH2fragment. The substituent planes at the C=C double bond of this fragment are twisted by 16.0 (3)° as a result of steric effects. The amine N(Et) N atom has a trigonal–pyramidal configuration (sum of the bond angles = 346.3°). The interplanar angle between the two carboxylate substituents is 60.39 (8)°. In the crystal, molecules form zigzag chains along [010] by intermolecular N—H...O hydrogen-bonding interactions, which are further packed in stacks toward [100]. The title azoninoindole might be considered as a candidate for the design of new Alzheimer drugs.

Synthesis and crystal structure of a cyanido-bridged copper(II)–silver(I) bimetallic complex containing a trimeric {[Ag(CN)2]−}3 anion, [Cu(Dach)2-Ag(CN)2-Cu(Dach)2][Ag(CN)2]3 (Dach=cis-1,2-diaminocyclohexane)

2017 ◽  
Vol 72 (1) ◽  
pp. 43-47 ◽  
Author(s):  
Sidra Nawaz ◽  
Abdul Ghaffar ◽  
Muhammad Monim-ul-Mehboob ◽  
Muhammad Nawaz Tahir ◽  
Mshari A. Alotaibi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Ir Spectroscopy ◽  
Bimetallic Complex ◽  
Apical Position ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Pyramidal Geometry ◽  
Square Pyramidal Geometry ◽  
Complex Ion

AbstractA new cyanido-bridged bimetallic copper(II)–silver(I) complex, [Cu(Dach)2-Ag(CN)2-Cu(Dach)2][Ag(CN)2]3 (1) (Dach=cis-1,2-diaminocyclohexane), has been prepared and characterized by IR spectroscopy and single crystal X-ray analysis. The crystal structure of complex 1 consists of a centrosymmetric trinuclear cation and three non-coordinated [Ag(CN)2]− ions assembled in the form of a trimer, {[Ag(CN)2]−}3. The complex ion is made up of two [Cu(Dach)2]2+ units connected by a bridging [Ag(CN)2]− anion. The copper atom in the complex ion assumes a distorted square pyramidal geometry with CN− nitrogen atoms occupying the apical position. The trinuclear units are joined by hydrogen bonding to form irregular chains.

Palladium(II) Complexes of Tridentate Ligands. The Crystal Structure of Chloro[2,6-di(2-imidazolin-2-yl)pyridine]palladium(II) Chloride

1991 ◽  
Vol 44 (12) ◽  
pp. 1659 ◽  
Author(s):  
AT Baker ◽  
DC Craig ◽  
P Singh
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Water Molecule ◽  
Complex Cation ◽  
Chloride Ions ◽  
Orthorhombic Space Group ◽  
Tridentate Ligands ◽  
X Ray ◽  
Square Planar ◽  
Bonding Scheme

Mono(ligand) palladium(II) complexes of 2,6-di-(thiazol-2-yl)pyridine (1a), 2,6-di(4-methylthia-zol-2-yl)pyridine (1b), 2,6-di(thiazol-4-yl)pyridine (2a), 2,6-di(imidazolin-2-yl]pyridine (3) and 2,6-di(benzimidazol-2-yl)pyridine (4a) of the general formula [ PdLCl ] Cl have been prepared. Stoichiometries have been confirmed by C, H, N and Pd analyses; the presence of solvate molecules has been confirmed by thermogravimetry . The crystal structure of [ PdLCl ]Cl.H2O, L = (3), has been determined by single-crystal X-ray diffractometry. The compound crystallizes in an orthorhombic space group, Pna21, a 7.427(2), b 21.932(3), c 8.935(1)Ǻ. The geometry of the complex cation is approximately square planar. The imidazolinyl rings closely approach planarity which is imposed by the delocalization of π-density in the NCN moiety. A hydrogen-bonding scheme involving the imino hydrogens of the ligand, chloride ions and the water molecule is present. The structure was refined by least-squares methods to a residual of 0.018 for 1273 reflections.

The oxidation of stannous halides by tetrahalogeno-ortho-quinones, and the crystal structure of bis[2-(dimethylamino)ethyldimethylammonium] tris(tetrachlorocatecholato)tin(IV), (Me2NC2H4NMe2H)2[Sn(O2C6Cl4)3]

1987 ◽  
Vol 65 (11) ◽  
pp. 2670-2676 ◽  
Author(s):  
Theodore A. Annan ◽  
Raj K. Chadha ◽  
Dennis G. Tuck ◽  
Katherine D. Watson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
X Ray ◽  
Crystallographic Study ◽  
The Stability

The reaction between SnX2 (X = Cl, Br, I), 1,10-phenanthroline (phen) and Y4C6O2 (Y = Cl, Br) yields Y4C6O2SnX2•phen with the o-quinone being converted to the corresponding catecholate anion. Reactions in which phen is replaced by Me2NC2H4NMe2 (tmen) are more complex, and the products depend in part on the solvent. These products include Cl4C6O2SnCl2•tmen, and products arising from solvation by ROH (R = CH3, C2H5). An X-ray crystallographic study of (tmenH)2[Sn(O2C6Cl4)3] shows that the anion contains a six-coordinate tin atom bonded to substituted catecholate anions. Hydrogen-bonding between cation and anion appears to be an important factor in the stability of the lattice.

Fractionation of polymethylene chains: An electron crystallographic investigation

1986 ◽  
Vol 44 ◽  
pp. 794-795
Author(s):  
Douglas L. Dorset
Keyword(s):  
Cross Section ◽  
Binary Systems ◽  
Linear Chain ◽  
Pure Component ◽  
Organic Substrates ◽  
Crystallographic Investigation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Sizes ◽  
The Stability

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.

Interactions of Ge Atoms with High- ê Oxide Dielectric Surfaces

2005 ◽  
Vol 879 ◽  
Author(s):  
Scott K. Stanley ◽  
John G. Ekerdt
Keyword(s):  
Oxide Layer ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Programmed Desorption ◽  
Tungsten Filament ◽  
X Ray ◽  
Dielectric Surfaces ◽  
Temperature Programmed ◽  
The Stability ◽  
Ge Nanocrystals

AbstractGe is deposited on HfO2 surfaces by chemical vapor deposition (CVD) with GeH4. 0.7-1.0 ML GeHx (x = 0-3) is deposited by thermally cracking GeH4 on a hot tungsten filament. Ge oxidation and bonding are studied at 300-1000 K with X-ray photoelectron spectroscopy (XPS). Ge, GeH, GeO, and GeO2 desorption are measured with temperature programmed desorption (TPD) at 400-1000 K. Ge initially reacts with the dielectric forming an oxide layer followed by Ge deposition and formation of nanocrystals in CVD at 870 K. 0.7-1.0 ML GeHx deposited by cracking rapidly forms a contacting oxide layer on HfO2 that is stable from 300-800 K. Ge is fully removed from the HfO2 surface after annealing to 1000 K. These results help explain the stability of Ge nanocrystals in contact with HfO2.

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