13C and 119Sn NMR evidence of the presence and extent of σ-π conjugation in some benzyltin compounds and their complexes

1988 ◽  
Vol 53 (3) ◽  
pp. 571-580 ◽  
Author(s):  
Jaroslav Holeček ◽  
Antonín Lyčka ◽  
Karel Handlíř ◽  
Milan Nádvorník
Keyword(s):  
Nmr Spectroscopy ◽  
Coordination Number ◽  
Aromatic Ring ◽  
Electronic System ◽  
Methyl Groups ◽  
Chlorine Atoms ◽  
Nmr Data ◽  
Relative Extent ◽  
119Sn Nmr

The 13C and 119Sn NMR spectroscopy has been used to study the compounds types (C6H5CH2)4-nSn(CH3)n and (C6H5CH2)4-nSnCln (n = 0 - 3) in media of non-coordinating (deuteriochloroform) and coordinating (hexadeuteriomethyl sulphoxide) solvents. The analysis of the NMR data has confirmed the presence and established the relative extent of participation of the σ-π conjugative connection of the polarized σ(Sn-C) bond with the adjacent π electronic system of the aromatic ring in the Sn-CH2-C6H5 grouping. The extent of σ-π conjugation decreases with decreasing number of methyl groups in the compounds (C6H5CH2)4-nSn(CH3)n and with increasing number of chlorine atoms in the compounds (C6H5CH2)4-nSnCln and with increasing coordination number of the central tin atom in the complexes of the compounds (C6H5CH2)4-nSnCln.x(C2H3)2SO.

scholarly journals Organoborierung von Alkinylstannanen, XIV Organoborierung von Bis(alkinyl)stannanen: Mechanismus und Anwendung der 119Sn–NMR-Spektroskopie/ Organoboration of Alkynylstannanes, XIV Organoboration of Bis(alkynyl)stannanes: Mechanism and Application of 119Sn NMR Spectroscopy

1984 ◽  
Vol 39 (8) ◽  
pp. 1037-1041 ◽  
Author(s):  
Susanna Kerschl ◽  
Bernd Wrackmeyer
Keyword(s):  
Quantitative Analysis ◽  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Product Distribution ◽  
Reaction Products ◽  
Nmr Data ◽  
119Sn Nmr ◽  
119Sn Nmr Spectroscopy

AbstractDimethylbis(phenylethynyl)stannane (1) reacts with trialkylboranes, BR3 (2), to give bis(alkenyl stannanes (5) (R = C2H5), 1-bora-4-stanna-2,5-cyclohexadienes (6 ) (R = C2H5, C3H7i), 1- stanna-2,4-cyclopentadienes (7) (R = C2H5) and l-stanna-3-cyclopentenes (8 ) (R = CH3, C2H5). 13C and 119Sn NMR data prove the structure of the reaction products (5 to 8 ). 119Sn NMR is useful (i) for following the course of the reaction (mechanism!) and (ii) for quantitative analysis of the product distribution. Deorganoboration reactions play an important role in the formation of the various heterocyclic systems.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

IR and 13C, 17O, and 119Sn NMR spectra of some bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids

1991 ◽  
Vol 56 (9) ◽  
pp. 1908-1915 ◽  
Author(s):  
Jaroslav Holeček ◽  
Antonín Lyčka ◽  
Milan Nádvorník ◽  
Karel Handlíř
Keyword(s):  
Infrared Spectroscopy ◽  
Nmr Spectroscopy ◽  
Dicarboxylic Acid ◽  
Nmr Spectra ◽  
Dicarboxylic Acids ◽  
119Sn Nmr ◽  
Carboxylic Groups ◽  
Cyclic Oligomers ◽  
The Media ◽  
Oxygen Atoms

Infrared spectroscopy and multinuclear (13C, 17O, and 119Sn NMR spectroscopy have been used to study the structure of bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids (1-C4H9)2. Sn(X(COO)2), where X = (CH2)n (n = 0-8), CH=CH (cis and trans) and C6H4 (ortho and para).The crystalline compounds are formed by linear or cyclic oligomers or polymers whose basic building units represent a grouping composed of the central tin atom substituted by two 1-butyl groups and coordinated with both oxygen atoms of two anisobidentate carboxylic groups derived from different molecules of a dicarboxylic acid. The environment of the tin atom has a shape of a trapezoidal bipyramid. When dissolvet in non-coordinating solvents, the compounds retain the oligomeric character with unchanged structure of environment of the central tin atom. In the media of coordinating solvents the bis(1-butyl)tin(IV) carboxylates of dicarboxylic acids form complexes whose central hexacoordinated tin atom binds two molecules of the solvent trough their donor atoms. Carboxylic groups form monodenate linkages in these complexes.

Investigation by NMR spectroscopy of the structural characteristics of modified oligo-nucleotides with pendant porphyrins

2019 ◽  
Vol 23 (07n08) ◽  
pp. 797-812 ◽  
Author(s):  
Sonja Merkaš ◽  
Mladen Žinić ◽  
Régis Rein ◽  
Nathalie Solladié
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Characteristics ◽  
Strong Interactions ◽  
Light Harvesting Complexes ◽  
The Past ◽  
Naturally Occurring ◽  
Nmr Data ◽  
Intermolecular Distances ◽  
Uracil Base ◽  
Biopolymer Scaffolds

During the past years, we focused on exerting control over the position and distance of porphyrins along our specifically designed oligonucleotidic scaffold. Indeed, in naturally occurring light-harvesting complexes, biopolymer scaffolds hold pigments at intermolecular distances that optimize photon capture, electronic coupling, and energy transfer. To this end, four uridine-porphyrin conjugates (a monomer, a dimer, a tetramer and an octamer) were subjected to a comprehensive conformational analysis by using NMR spectroscopy. The collected NOE NMR data highlighted characteristic and strong interactions indicating that the glycosidic angle between the ribose and uracil base is anti. In order to further investigate the conformation of this family of molecules, NMR experiments were carried out at variable temperatures. At low temperature, the signals of the porphyrinic protons decoalesce, showing two sets of [Formula: see text]-pyrrolic protons. Similar observations are made for signals corresponding to sugar moieties and especially the H1′ protons, indicating molecular motions within our porphyrin-uridin arrays. These results testify in favor of the existence of a dynamic process between C3′-endo and C2′-endo conformations.

Dependence of the conversion of chlorophenols by rhodococci on the number and position of chlorine atoms in the aromatic ring

Microbiology ◽  
2000 ◽  
Vol 69 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Z. I. Finkel’shtein ◽  
B. P. Baskunov ◽  
E. L. Golovlev ◽  
O. V. Moiseeva ◽  
J. Vervoort ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Chlorine Atoms

Structure and stereochemistry in 'f-block' complexes of high coordination number. VII. The [M(unidentate X)2(unidentate Y)6] system: Crystal structure of hexaaquadichloroeuropium(III) chloride (a redetermination)

1983 ◽  
Vol 36 (3) ◽  
pp. 477 ◽  
Author(s):  
DL Kepert ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Coordination Number ◽  
Title Compound ◽  
Chlorine Atoms ◽  
Coordination Environment ◽  
Twofold Axis ◽  
High Coordination Number ◽  
Europium Atom ◽  
High Coordination

The crystal structure of the title compound [EuCl2(OH2)2]Cl ('europium trichloride hexahydrate') has been redetermined from single-crystal diffractometer data at 295 K and refined to a residual of 0.040 for 1094 independent 'observed' reflections. Crystals are monoclinic, P2/n, a 9.659(3), b 6.529(2), c 7.936(4) �, β 93.67(4)�, Z 2. The europium atom lies on a crystallographic twofold axis, which passes between the two planes of a square-antiprismatic coordination environment in which the two chlorine atoms, on opposite faces, lie cis to each other. Eu-O distances range from 2.401(6) to 2.431(5) �; Eu-Cl is 2.774(2) �.

Hexaethyl-2,4-dicarba-nido-hexaborane(8), Deprotonation and Complexation Studied by NMR Spectroscopy and Density Functional Theory (DFT) Calculations

2004 ◽  
Vol 59 (6) ◽  
pp. 685-691 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Jörg Schanz
Keyword(s):  
Density Functional Theory ◽  
Nmr Spectroscopy ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Analogous Reaction ◽  
Sandwich Complex ◽  
Dft Methods ◽  
Functional Theory ◽  
Nmr Data

Deprotonation of hexaethyl-2,4-dicarba-nido-borane(8) 2 leads first to the hexaethyl-2,4-dicarbanido- borate(1−) 3, and further deprotonation, using BuLi/KOtBu, gives the hexaethyl-2,4-dicarbanido- hexaborate(2−) 4. The reaction of 3 with FeCl2 affords the commo-ferracarborane [Fe(Et6-2,4- C2B4H)2] 5, and the analogous reaction of 4 leads to the anionic sandwich complex [Fe(Et6-2,4- C2B4)2]2− 6 which can be protonated to give 5. The complex 5 contains two hydrido ligands, each bridging the iron and two boron atoms. Reactions were monitored and the products were characterised by 11B NMR spectroscopy in solution. The geometries of the carboranes, the borates (all unsubstituted and permethyl-substituted) and the iron complexes (all unsubstituted) were optimised by DFT methods [B3LYP/6-311+G(d,p) or B3LYP/6-31+G(d)], and the relevant NMR data [chemical shifts δ11B, δ13C, δ57Fe, and coupling constants 1J(13C,1H), 1J(11B,1H), 1J(57Fe,1H), 1J(57Fe,11B)] were calculated at the same level of theory.

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