Multinuclear magnetic resonance studies of the aqueous products of the complexes cis- and trans-Pt(Ypy)2(NO3)2 where Ypy = pyridine derivative

2002 ◽  
Vol 80 (4) ◽  
pp. 379-387 ◽  
Author(s):  
Fernande D Rochon ◽  
Christian Tessier
Keyword(s):  
Nmr Spectroscopy ◽  
The Other ◽  
Basic Medium ◽  
Pyridine Derivative ◽  
Neutral Medium ◽  
Coupling Constant ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Cis And Trans ◽  
Ortho Substituent

The hydrolyis or the aquation reactions of compounds of the types cis- and trans-Pt(Ypy)2(NO3)2 (Ypy = pyridine derivative) were studied in D2O and characterized by multinuclear (195Pt, 13C, and 1H) NMR spectroscopy. In acidic pD, the product of the cis complexes is cis-[Pt(Ypy)2(D2O)2]2+, whereas in basic medium cis-Pt(Ypy)2(OD)2 is formed. The 195Pt NMR resonances of the products containing ligands with an ortho substituent were observed at lower fields than the other complexes. The average coupling constant (3J(195Pt–1H) and 3J(195Pt–13C)) is 44 Hz for the diaqua species and 42 Hz for the dihydroxo compounds. At neutral pD, several hydrolyzed species were observed, except for the 2-picoline and 2,4-lutidine complexes, which contained only one compound, cis-[Pt(Ypy)2(D2O)(OD)]+. The other hydrolyzed products for the ligands with no ortho substituent were identified as the dihydroxo-bridged dimer, the monohydroxo-bridged dimer, the trimer, and possibly the tetramer. The trans analogues have shown two signals in acidic pD corresponding to the diaqua monomer and the monohydroxo-bridged aqua dimer. Two species (the dihydroxo compound and the monohydroxo-bridged hydroxo dimer) were also observed in basic pD. In neutral medium, a third signal assigned to a longer chain hydroxo-bridged oligomer or polymer was detected.Key words: platinum, pyridine derivative, nitrato, hydrolysis, NMR, aquation.

Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XXXI [1]. Synthese und Dynamik von Acetyl-carbonyl-η5-cyclopentadienyl-η4-dien-wolfram-Komplexen / Hindered Ligand Movements in Transition Metal Complexes, XXXI [1]. Syntheses and Dynamics of Acetyl-carbonyl-η5-cyclopentadienyl-η4-diene-tungsten Complexes

1986 ◽  
Vol 41 (5) ◽  
pp. 599-605 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Kurt Nist ◽  
Joachim Kögler
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Conjugated Dienes ◽  
The Other ◽  
Molecular Plane ◽  
H Nmr ◽  
Tungsten Complexes ◽  
Diene Ligands

Tricarbonyl-η5-cyclopentadienyl-methyl-tungsten (1) reacts upon UV irradiation with conjugated dienes, like 1,3-butadiene (2), E-1,3-pentadiene (3), 2-methyl-1,3-butadiene (4), 2,3-dimethyl-1,3- butadiene (5), 1,3-cyclopentadiene (6) and 1,3-cyclohexadiene (7), to give the corresponding, quasisquare- pyramidal [(η5-C5H5)W(CO)(COCH3)(η4-diene)] complexes (8-13). With the unsymmetrically substituted dienes 3 and 4, only one of the possible diastereotopic complexes are obtained. At 200 to 230 K, 8-12 show two isomers, which are distinguished by the orientations (o or u) of the diene with respect to the other ligands. The interconversion of the o- and u-isomers was studied by dynamic 1H NMR spectroscopy and is explained by an intramolecular ±180° rotation of the diene ligands in the molecular plane. The barriers o f activation ⊿G* 300 are between 57.8 and 61.0 ± 1 kJ/mol.

High resolution nuclear magnetic resonance studies of platinum(II) – guanosine-5′-monophosphate interactions in aqueous solutions

1981 ◽  
Vol 59 (23) ◽  
pp. 3297-3302 ◽  
Author(s):  
Moschos Polissiou ◽  
Minh Tan Phan Viet ◽  
Maurice St-Jacques ◽  
Theophile Theophanides
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Aqueous Solutions ◽  
Conformational Changes ◽  
Coupling Constant ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Nmr Study ◽  
Ribose Moiety

A detailed 400 MHz 1H nmr study was carried out on platinum complexation products of GMP by K2PtCl4. Coupling constant values show that platination on N7 induces a conformational change on the ribose moiety: the 3E form of the ring and the gt conformer about the C(4′)—C(5′) bond are favoured upon complexation. The results are compared to the conformational changes induced by N7 protonation and methylation.

Molybdenum-95 nuclear magnetic resonance studies on disubstituted molybdenum(0) carbonyls

1988 ◽  
Vol 66 (3) ◽  
pp. 397-400 ◽  
Author(s):  
Elmer C. Alyea ◽  
Arpad Somogyvari
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Phosphine Ligands ◽  
Electronic Effects ◽  
Magnetic Resonance Studies ◽  
Nitrogen Ligands ◽  
Cis And Trans ◽  
Cyclic Nitrogen

Molybdenum-95 nmr spectral data are reported for 40 cis- and trans-Mo(CO)4LL′ compounds and the chemical shifts discussed in relation to a simplified Ramsey expression for the paramagnetic shielding term. The identification of mixtures of products of the type Mo(CO)6−nLn is shown to be easily accomplished by 95Mo nmr spectroscopy. The 95Mo chemical shifts provide a sensitive probe of structural and electronic effects, as illustrated for several cyclic nitrogen ligands as well as a range of phosphine ligands in the Mo(CO)4LL′ complexes.

Synthesis and properties of oxytocin analogues modified in the tripeptide side chain

1984 ◽  
Vol 49 (3) ◽  
pp. 642-652 ◽  
Author(s):  
Zdenko Procházka ◽  
Michal Lebl ◽  
Tomislav Barth ◽  
Jan Hlaváček ◽  
Antonín Trka ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Biological Activities ◽  
The Other ◽  
Side Chain ◽  
H Nmr ◽  
Fragment Condensation

Two oxytocin analogues were synthesized by fragment condensation (6 + 3) in the presence of dicyclohexylcarbodiimide and 1-hydroxybenzotriazole. In one of the analogues, proline in the position 7 and leucine in the position 8 were substituted by 2-[1-(2-oxo-3-aminopyrrolidinyl)]-4-methylpentanoic acid, in the other proline was replaced by 1-aminocyclopropane-1-carboxylic acid. Biological activities of the first analogue were strongly reduced and dissociation of the uterotonic and galoctogogic activities was observed with both the analogues. The structure of 2-(3-tert-butyloxycarbonylaminopyrrolidin-2-on-1-yl)-4-methylpentanoylglycine and its amide was confirmed by mass and 1 H NMR spectroscopy.

Assignment of cis-trans Geometry in Diastereomeric 2-Benzyl-4-methyl-1,3,2-dioxaphosphorinans and their 2-Oxo- and 2-Seleno-Derivatives

1975 ◽  
Vol 30 (9-10) ◽  
pp. 710-715 ◽  
Author(s):  
W. J. Stec ◽  
K. Lesiak ◽  
D. Mielczarek ◽  
B. Stec
Keyword(s):  
Nmr Spectroscopy ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Spin Coupling Constant ◽  
Geometrical Isomers ◽  
Benzyl Halides ◽  
New Compounds ◽  
Cis And Trans ◽  
Spin Spin Coupling ◽  
C Nmr

MICHAELIS-ARBUSOV reaction of diastereoisomeric 2-methoxy-4-methyl-1,3,2-dioxaphosphorinans with benzyl halides is non-stereospecific. Cis- and trans-2-benzyl-2-oxo-4-methyl-1,3,2-dioxaphosphorinans were separated and analysed by means of IR, 31P and 13C NMR spectroscopy. 2-Benzyl-2-seleno-4-methyl-1,3,2-dioxaphosphorinans were synthesized and stereospecifically converted to 2-oxo-analogues. Stereochemistries are assigned to the geometrical isomers of all new compounds described in this paper. Application of direct spin-spin coupling constant values for structural elucidation is emphasized.

Preparation of (Z)-3,4-didehydronorvaline, (E)- and (Z)-3,4-didehydroornithine and (E)- and (Z)-3,4-didehydro-2,6-diaminopimelic acid

1990 ◽  
Vol 55 (8) ◽  
pp. 2074-2085 ◽  
Author(s):  
Libor Havlíček ◽  
Jan Hanuš ◽  
Petr Sedmera ◽  
Jan Němeček
Keyword(s):  
Nmr Spectroscopy ◽  
Diaminopimelic Acid ◽  
Grignard Reagents ◽  
Basic Medium ◽  
H Nmr

(Z)-3,4-Didehydronorvaline (IIa), (E)- and (Z)-didehydroornithine (VIb and VIa, respectively) and (E)- and (Z)-3,4-didehydro-2,6-diaminopimelic acid (Xb and Xa, respectively) were prepared by addition of Grignard reagents to diethyl acetiminomalonate and subsequent reactions. The mechanism of cyclization of 2-acetamido-2-alkynylmalonate to the oxazoline derivative in a basic medium was studied by 1H NMR spectroscopy.

scholarly journals Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

2020 ◽  
Vol 16 ◽  
pp. 22-31
Author(s):  
Andreas H Heindl ◽  
Hermann A Wegner
Keyword(s):  
Nmr Spectroscopy ◽  
Smart Materials ◽  
Storage Capacity ◽  
Aryl Halides ◽  
Information Storage ◽  
The Other ◽  
Coupling Reactions ◽  
Efficient Synthesis ◽  
H Nmr ◽  
New Class

Multistate switches allow to drastically increase the information storage capacity and complexity of smart materials. In this context, unsymmetrical 1,3,5-tris(arylazo)benzenes – ‘starazos’ – which merge three photoswitches on one benzene ring, were successfully prepared. Two different synthetic strategies, one based on Baeyer–Mills reactions and the other based on Pd-catalyzed coupling reactions of arylhydrazides and aryl halides, followed by oxidation, were investigated. The Pd-catalyzed route efficiently led to the target compounds, unsymmetrical tris(arylazo)benzenes. These triple switches were preliminarily characterized in terms of their isomerization behavior using UV–vis and 1H NMR spectroscopy. The efficient synthesis of this new class of unsymmetrical tris(arylazo)benzenes opened new avenues to novel multistate switching materials.

scholarly journals Electron Release and Proton Acceptance Reactions of (dpp-BIAN)Mg(THF)3

2008 ◽  
Vol 63 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Igor L. Fedushkin ◽  
Valentina A. Chudakova ◽  
Markus Hummert ◽  
Herbert Schumann
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Ir Spectroscopy ◽  
The Other ◽  
X Ray ◽  
H Nmr ◽  
Trigonal Bipyramidal ◽  
Electron Release ◽  
Coordination Spheres ◽  
Centrosymmetric Dimers

(dpp-BIAN)Mg(THF)3 (1) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) and (PhCOO)2 react with splitting of the peroxide bridge and formation of the dimeric magnesium benzoate [(dpp-BIAN)MgOCOPh(THF)]2 (2). The reaction of 1 with PhCOOH yields the dimeric magnesium benzoate [(dpp-BIAN)(H)MgOCOPh(THF)]2 (3), whereas 1 and furanyl-2-carboxylic acid react with liberation of hydrogen and formation of (dpp-BIAN)Mg[OCO(2-C4H3O)]2 Mg(dpp-BIAN)(THF) (4). Compounds 2, 3, and 4 have been characterized by elemental analysis, IR spectroscopy, and X-ray structure analysis, compound 3 also by 1H NMR spectroscopy. The eightmembered metallacycles of the centrosymmetric dimers 2 and 3 are almost completely planar. The two magnesium atoms in 4 show different coordination spheres; one is surrounded by its ligands in a trigonal bipyramidal manner, the other one in a tetrahedral fashion. The Mg···Mg separations in 2, 3 and 4 are 4.236, 4.296, and 4.030 Å, respectively

Mixed behavior of p-phenylenediaminium guest binding with the inverted cucurbit[6]uril host

2015 ◽  
Vol 13 (30) ◽  
pp. 8330-8334 ◽  
Author(s):  
De-Qing Zhang ◽  
Rui-Lian Lin ◽  
Wen-Qi Sun ◽  
Zhu Tao ◽  
Qian-Jian Zhu ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Sandwich Structure ◽  
The Other ◽  
Binding Interaction ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Guest Binding ◽  
Different Types ◽  
Inclusion Structure

The binding interaction between inverted cucurbit[6]uril (iQ[6]) and p-phenylenediaminium has been investigated by X-ray crystallography, 1H NMR spectroscopy and ITC. Our data indicate that the host and the guest can form two different types of complexes: one is an inclusion structure and the other is a sandwich structure.

Novel mixed-ligand Pt(II) complexes: Synthesis, multinuclear magnetic resonance, and crystal structures of cis- and trans-Pt(R2SO)(pyrazine)Cl2

2004 ◽  
Vol 82 (5) ◽  
pp. 649-658 ◽  
Author(s):  
Fernande D Rochon ◽  
Julien RL Priqueler
Keyword(s):  
Crystal Structure ◽  
Magnetic Resonance ◽  
Ir Spectroscopy ◽  
Crystal Structures ◽  
Mixed Ligand ◽  
The Other ◽  
Coupling Constant ◽  
New Type ◽  
Cis And Trans ◽  
Multinuclear Magnetic Resonance

A new type of mixed-ligand Pt(II) complexes, Pt(R2SO)(pyrazine)Cl2, was synthesized from the aqueous reaction of K[Pt(R2SO)Cl3] with pyrazine. The compounds were characterized mainly by IR and multinuclear magnetic resonance spectroscopies (1H, 13C, and 195Pt) and crystallography. Compounds with dimethylsulfoxide, tetramethylenesulfoxide, di-n-propylsulfoxide, di-n-butylsulfoxide, dibenzylsulfoxide, and diphenylsulfoxide were studied. IR spectroscopy suggested a cis geometry for the di-n-propylsulfoxide complex and trans geometry for the other compounds. The 195Pt NMR resonances of the complexes were observed between –3042 and –3121 ppm, with that of the diphenylsulfoxide complex being at higher field than those of the others. The pyrazine 3J(195Pt-1H) coupling constant was observed for the DMSO compound (33 Hz), suggesting a trans geometry. No J(195Pt-13C) coupling could be detected. The crystal structures of trans-Pt(tetramethylenesulfoxide)(pyrazine)Cl2 and of cis-Pt(di-n-propylsulfoxide)(pyrazine)Cl2 were determined and confirmed the geometry suggested by IR and NMR spectroscopies. The compound with di-n-butylsulfoxide could not be isolated, because it rapidly formed the pyrazine-bridged dimer. Key words: platinum, sulfoxide, pyrazine, crystal structure, NMR, IR.

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