Effect of ring size on properties of technetium amine oxime complexes. X-ray structures of TcO2Pent(AO)2, which contains an unusual eight-membered chelate ring, and of TcOEn(AO)2

1987 ◽  
Vol 26 (21) ◽  
pp. 3576-3582 ◽  
Author(s):  
Silvia Jurisson ◽  
Karl Aston ◽  
C. Kay Fair ◽  
Elmer O. Schlemper ◽  
Paul R. Sharp ◽  
...  
Keyword(s):  
Chelate Ring ◽  
Ring Size ◽  
X Ray ◽  
Membered Chelate Ring

Boron Chelates and Boron-Metal Chelates, X [1]. 3-(2-Hydroxyphenyl)-2,2-diphenyl-1-oxa-3-azonia-2-borata-naphthalene-methanol (1/1): Synthesis, Spectroscopic Investigations and Crystal Structure

1982 ◽  
Vol 37 (11) ◽  
pp. 1450-1455 ◽  
Author(s):  
Rudolf Allmann ◽  
Eberhard Hohaus ◽  
Stanislaw Olejnik
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Analysis ◽  
Title Compound ◽  
Chelate Ring ◽  
Boron Chelates ◽  
X Ray ◽  
Membered Chelate Ring ◽  
Compound C ◽  
Overall Ratio

The title compound, C25H20BNO2 · CH3OH, was examined by UV, IR, 1H, and 13C NMK spectroscopy as well as by thermogravimetry and X-ray structure analysis (Pbnb, a = 8.815, b = 17.309, c=28.992 Å, R= 5.5%). These investigations show the six-membered chelate ring (chelate A) to exist as formulated in [2] and not as a five-membered chelate ring B. One methanol molecule connects two chelate molecules by hydrogen bonds, resulting in an overall ratio of chelate to methanol of 1 : 1.

Induction of Λ-helicity in a zinc complex with an alanine-appended aminopyridine ligand

2021 ◽  
Vol 77 (8) ◽  
Author(s):  
Berislav Perić ◽  
Zoran Kokan ◽  
Srećko I. Kirin
Keyword(s):  
Zinc Complex ◽  
Chelate Ring ◽  
Ionic Interactions ◽  
Stacking Interactions ◽  
Neutral Ligand ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Third ◽  
Membered Chelate Ring ◽  
The Stability

The crystal structure of tris[dimethyl 5-({1-[(pyridin-2-yl-κN)carbamoyl-κO]ethyl}carbamoyl)benzene-1,3-dicarboxylate]zinc(II) dinitrate acetonitrile trisolvate, [Zn(C19H19N3O6)3](NO3)2·3CH3CN or [Zn(L)3](NO3)2·3CH3CN, (1), has been determined by single-crystal X-ray diffraction. The neutral ligand L coordinates to the Zn2+ cation in a bidentate fashion via the pyridine N atom and an amide O atom, forming a six-membered chelate ring. The Λ-helical chirality of the Zn2+ coordination sphere is induced by pendant L-alanine residues through stacking interactions between the arene groups of two coordinated ligands, assisted by a hydrogen bond between amide groups bonded to the stacked arene rings. The third ligand is coordinated to the Zn2+ cation by the same six-membered chelate ring, but in the opposite direction with respect to the analogous chelate rings of the first two coordinated ligands. Besides ionic interactions between [ZnL 3]2+ complexes and NO3 − anions, several types of hydrogen bonds and intermolecular stacking interactions contribute to the stability of the solid-state phase.

Trifluoromethylaryl-Substituted Quinoxalines: Unusual Ruthenium- Amidininate Complexes and their Suitability for Anellation Reactions

2005 ◽  
Vol 60 (8) ◽  
pp. 843-852 ◽  
Author(s):  
Frank Schramm ◽  
Dirk Walther ◽  
Helmar Görls ◽  
Christian Käpplinger ◽  
Rainer Beckert
Keyword(s):  
Boron Trifluoride ◽  
Chelate Ring ◽  
Ruthenium Complex ◽  
Structural Motif ◽  
X Ray Diffraction ◽  
Quinoxaline Derivative ◽  
Imidazolium Salt ◽  
X Ray ◽  
Membered Chelate Ring ◽  
Complex Fragment

The reaction of the 2,3-dianilino-quinoxaline 1 with an equivalent of triethyl orthoformiate results in a cyclic aminalester 2. An excess of triethyl orthoformate results in the carbene dimer 4. With the help of boron trifluoride, 2 can be transformed into the imidazolium salt 3. Reaction of 1 with KOtC4H9 leads to a quinoxaline derivative 5 under anellation of a benzene ring whereas the related pyrazino-quinoxaline 6 (formed from tetraaminobenzene tetrahydrochloride and bis-(3- trifluoromethylphenyl) oxalimidoyl chloride) does not react under similar conditions. However, 6 can be activated towards anellation by employing the complex fragment [(tbbpy)2Ru]2+, tbbpy: bis(4,4’-di-tert-butyl-2,2’-bipyridine). This generates an unusual ruthenium complex 9 which could be characterised by X-ray diffraction. Complex 9 contains a pentacene derivative and coordinates the ruthenium fragment at the amidinate moiety thus forming a four-membered chelate ring. Isolation of a second ruthenium complex 8 which contains an intact pyrazino-quinoxaline 6 in which the metal is also coordinated to an amidinato group supports the assumption that the anellation reaction occurs only after metal complexation at the amidinate group. In contrast to this, the smaller [(tmeda)2Pd]2+ fragment reacts with the pyrazino-quinoxaline 6 to form the mononuclear Pd complex 10. Its structural motif (X-ray diffraction) shows that the palladium centre coordinates at the 1,4-diamino group of the intact pyrazino-quinoxaline to form a five-membered chelate ring. This suggests that the bulkiness of the complex fragment determines whether or not an anellation reaction can take place.

Synthesis and X-Ray Structure of a Heterovalent, Cycloaurated Pentafluorophenylgold(I)/Pentafluorophenylgold(III) Complex

2002 ◽  
Vol 55 (4) ◽  
pp. 267 ◽  
Author(s):  
M. A. Bennett ◽  
S. K. Bhargava ◽  
F. Mohr ◽  
L. L. Welling ◽  
A. C. Willis
Keyword(s):  
Chelate Ring ◽  
Gold Atom ◽  
Linear Arrangement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Membered Chelate Ring ◽  
Square Planar

The heterovalent gold(I)/gold(III) complex [(C6F5)AuI(μ-2-Ph2PC6H3-6-Me)AuIII(C6F5){η2-(6-MeC6H3-2-PPh2)}] has been prepared and structurally characterized by X-ray crystallography. It shows square planar stereochemistry at AuIII incorporating a four-membered chelate ring and linear arrangement at AuI. The compound is a rare example of a heterovalent complex containing an aryl ligand on each gold atom.

Complexes of Tris(N-piperidinomethyl)phosphine Oxide with Zinc and Cadmium

1996 ◽  
Vol 61 (9) ◽  
pp. 1321-1334 ◽  
Author(s):  
Pavel Vojtíšek ◽  
Ivana Císařová
Keyword(s):  
Coordination Sphere ◽  
Phosphine Oxide ◽  
Chelate Ring ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Membered Chelate Ring ◽  
Other Hand ◽  
Ring Structures ◽  
The Way

A number of compounds which can by their stoichiometry be classified into several groups have been prepared by reaction of tris(N-piperidinomethyl)phosphine oxide (tppo) with Zn(II) and Cd(II) salts. The structure of two Zn(II) complexes differing by their Zn : tppo ratio and of one Cd(II) complex has been determined by the X-ray diffraction technique. The results show that in all the cases tppo is bound as divalent chelate N,O-donor, but the geometry of coordination sphere of M(II) decisively affects the steric arrangement of the five-membered chelate ring. Structures of the compounds studied are entirely different from those of Zn(II) complexes of sterically less demanding P,P-dimethyl-P-aminomethylphosphine oxide (dmao). On the other hand, the way of coordination of tppo is the same as that found in the case of the Co(II) complex of tris(N,N-dimethylaminomethyl)phosphine oxide.

Sign in / Sign up

Export Citation Format

Share Document