PROTONATED CARBONYL GROUPS II. γ-PYRIDONE SALTS

1963 ◽  
Vol 41 (10) ◽  
pp. 2575-2584 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Nitrogen Atom ◽  
Oxygen Atom ◽  
Organic Cation ◽  
Deformation Mode ◽  
Carbonyl Oxygen ◽  
Carbonyl Groups ◽  
Hydrated Form ◽  
Strong Band ◽  
Mineral Acids ◽  
Hydrogen Bonded

The salts of 1,2,6-trimethyl-4-pyridone and 1-ethyl-2,6-dimethyl-4-pyridone and mineral acids and their deuterated analogues have been prepared and their spectra recorded. The spectra are consistent with protonation at the carbonyl oxygen atom, not the nitrogen atom. Many similarities with the spectra of γ-pyrone salts (D. Cook. Can. J. Chem. 41, 505 (1963)) have been observed, voh varies from 2495 cm−1 in the HCl salt to 3470 cm−1 in the HPF6 salt. The deformation mode, vOH, is much more constant in frequency and is doubled, near 1300 and 1230 cm−1, probably due to correlation field splitting. A few of the more strongly hydrogen-bonded salts have torsional modes around 800 cm−1.Many of the salts can also be prepared in a hydrated form which contains the same organic cation, probably hydrogen bonded to chains of water molecules.In one case a salt containing 2 molecules of the base to 1 of acid (HAsF6) has been prepared. The spectrum contains a very broad, strong band, near 1300 cm−1, probably due to the species [Formula: see text].

An electron spin resonance and CIDNP study of the structure and reactivity of some excited triplet biphenyl ketones

1977 ◽  
Vol 55 (7) ◽  
pp. 1175-1180 ◽  
Author(s):  
Harish M. Vyas ◽  
Jeffrey K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperature ◽  
Light Intensity ◽  
Oxygen Atom ◽  
Carbonyl Oxygen ◽  
Zero Field ◽  
Carbonyl Groups ◽  
Excited Triplet ◽  
Spin Resonance ◽  
Unpaired Spin

The correlation of structure and reactivity of some excited triplet biphenyl ketones was approached by a combined esr and CIDNP study. The low temperature esr study confirmed the assignment of the triplet π,π* as the lowest triplet state in these biphenyl ketones. An analysis of the zero-field energies suggests that these π,π* triplets have a structure with both the biphenyl and the carbonyl groups being coplanar. Consequently a substantial unpaired spin density may result at the carbonyl oxygen atom which could lead to abstraction reactions. The CIDNP results are consistent with the triplet photoreduction mechanism. The polarization is mainly due to the cage products and the polarization magnitude is therefore dependent upon the light intensity

The Phenomenon of Intramolecular Attractive S---O Interactions: Synthesis and Structure of (1,10-Phenanthroline)copper(II) Complexes with Isonitroso-(4-methylthiazol-2-yl)acetamide and Isonitroso-(4-methylthiazol-2-yl)-(benzothiazol-2-yl)methanide

1997 ◽  
Vol 52 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Konstantin V. Domasevitch ◽  
Vera V. Ponomareva ◽  
Andrey A. Mokhir ◽  
Eduard B. Rusanov ◽  
Joachim Sieler ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Oxygen Atom ◽  
Chlorine Atom ◽  
Carbonyl Oxygen ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
Trigonal Bipyramidal ◽  
Bidentate Chelate

Abstract Isonitroso-(4-methylthiazol-2-yl)acetamide H (L1), isonitroso-(4-methylthiazol-2-yl)(benzo-thiazol-2-yl)methanide H(L2) and their copper(II) complexes of composition [Cu(Phen){L1}(ClO4)] (1) and [Cu(Phen){L2}Cl]*C2H5OH (2) have been prepared. Crystal and molecular structures of the complexes have been determined from X-ray diffractioon data (1: monoclinic, space group P21/c, with a = 11.611(2), b = 10.259(2), c = 17.869(4) Å, β = 104.67(3)°, V = 2059.1(7) Å3, Z = 4; R1 = 0.046 for the 2522 unique reflections with I > 2σ(I). 2: triclinic, space group P1̄, with a = 8.351(1), b = 10.876(1), c = 14.891(2) Å, a = 96.170(8)°, β = 94.201(9)°, γ = 106.721(9)°, V = 1280.1(2) Å3, Z = 2; R1 = 0.034 for the 4038 unique reflections with I > 2σ(I)). In the structure of 1 the coordination polyhedron of Cu2+ is a distorted square pyramid with an oxygen atom of the CIO4 counter anion in the apex (C u -O 2.505(3) Å); in complex 2 the copper atom adopts fivefold coordination of a slightly distorted trigonal-bipyramidal geometry with a chlorine atom in the equatorial plane (Cu-Cl 2.3504(9) A). Ethanol of crystallization gives rise to a hydrogen bond at the chlorine atom. In both structures the oximic anions are coordinated to the metal center in a bidentate chelate manner via the nitrogen atom of the nitroso group and the carbonyl oxygen atom (1) or via the benzothiazole nitrogen atom (2) (Cu-O, Cu-N in the range 1.963(2) -2.031 (2) Å). The thiazole group of the ligands takes no part in the coordination. The nitroso oxygen atoms possess short intramolecular contacts with thiazole sulphur atoms, with d(S--- O) at 2.605(3) (1) and 2.676(3) A (2), which may be attributed to a strong intraligand interaction.

PROTONATED CARBONYL GROUPS: IV. N,N-DIMETHYLACETAMIDE SALTS

1964 ◽  
Vol 42 (12) ◽  
pp. 2721-2727 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Oxygen Atom ◽  
Infrared Spectra ◽  
Deformation Mode ◽  
Carbonyl Groups ◽  
Broad Absorption ◽  
Average Value ◽  
Correlation Field ◽  
Bending Mode ◽  
Out Of Plane ◽  
Transmission Windows

The infrared spectra of N,N-dimethylacelamide salts have been recorded and are consistent with protonation at the oxygen atom, vOH is between 2 095 and 3 360 cm−1 depending on the anion. The average value of the two components of the OH in-plane hydrogen-bending mode, δOH, is 1 253 cm−1 (splitting of about 147 cm−1 due to correlation field effects). The out-of-plane hydrogen-deformation mode occurs at 928 to 761 cm−1 depending on the salt. The 1 680 and 1 400 cm−1 bands which are present in all the salts are associated chiefly with stretching the CN and CO bonds respectively, in the OCN group, though it is likely that the vibrations are somewhat mixed.Some salts of complex acids are of the 2 base: 1 acid variety with very strong broad absorption centered near 900 cm−1, containing sharp transmission windows.

Conformation and electronic structure of aromatic chloroformates

1987 ◽  
Vol 52 (4) ◽  
pp. 970-979 ◽  
Author(s):  
Otto Exner ◽  
Pavel Fiedler
Keyword(s):  
Electronic Structure ◽  
Oxygen Atom ◽  
Strong Interaction ◽  
Electron Distribution ◽  
Room Temperature ◽  
Functional Group ◽  
Dipole Moments ◽  
Carbonyl Oxygen ◽  
Nonpolar Solvents ◽  
Single Method

Aromatic chloroformates Ib-Ie were shown to exist in the ap conformation, in agreement with aliphatic chloroformates, i.e. the alkyl group is situated cis to the carbonyl oxygen atom as it is the case in all esters. While 4-nitrophenyl chloroformate (Ie) is in this conformation in crystal, in solution at most several tenths of percent of the sp conformation may be populated at room temperature and in nonpolar solvents only. A new analysis of dipole moments explained the previous puzzling results and demonstrated the impossibility to determine the conformation by this single method, in consequence of the strong interaction of adjoining bonds. If, however, the ap conformation is once proven, the dipole moments reveal some features of the electron distribution on the functional group, characterized by the enhanced polarity of the C-Cl bond and reduced polarity of the C=O bond. This is in agreement with the observed bond lengths and angles.

Chemistry of Aminochromes. Part XVIII. The Effects of pH and Substituents on some Aminochrome–Thiol Reactions

1974 ◽  
Vol 52 (6) ◽  
pp. 1019-1026 ◽  
Author(s):  
W. S. Powell ◽  
R. A. Heacock
Keyword(s):  
Addition Product ◽  
Carbonyl Oxygen ◽  
Carbonyl Groups ◽  
Effects Of Ph ◽  
Acidic Conditions ◽  
Ph Range

Aminochromes react with thiols in the pH range ca. 3–4 to give mainly 4-thiosubstituted-5,6-dihydroxyindoles (or the corresponding 5,6-dihydroxyindolines) along with reduction products (5,6-dihydroxyindoles or 5,6-dihydroxyindolines). There is also some evidence, in this pH range, for the formation of an addition product involving one of the aminochrome carbonyl groups directly. Under somewhat less acidic conditions (pH 5–6), however, the major products formed initially are, in general, 3a-thiosubstituted-3a, 4-dihydroaminochromes. These products, which are formed reversibly, are gradually replaced in the reaction mixture by the indolic products, which are formed irreversibly. The increased rate of formation of the 4-thiosubstituted-5,6-dihydroxyindoles at lower pH's is probably due to the increased protonation of the C-6 carbonyl oxygen. The 3a-thiosubstituted-3a, 4-dihydroaminochromes may be formed more readily at higher pH's due to the increased ionization of the thiol.

A New Binuclear Lutetium(III) Dimethyl-N-trichloroacetylamidophosphate Complex with a γ, γ'-Dipyridyl Bridge, {Lu[CCl3C(O)NP(O)(OCH3)2]3}2-μ(γ,γ'-dipy)

2001 ◽  
Vol 56 (3) ◽  
pp. 249-254 ◽  
Author(s):  
Victor A. Trush ◽  
Jolanta Swiatek-Kozlowska ◽  
Victor V. Skopenko ◽  
Vladimir M. Amyrkhanov
Keyword(s):  
Crystal And Molecular Structure ◽  
Carbonyl Oxygen ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Metal Centers ◽  
X Ray ◽  
Heterocyclic Ligand ◽  
New Type ◽  
Ir Spectroscopic

Abstract A new type of binuclear coordination compound of lutetium, {Lu2L6 · μ-(γ,γ '-dipy)} (where L = dimethyl-N-trichloroacetylamidophosphate anion and γ,γ '-dipy = 4,4'-dipyridyl), has been obtained. The IR spectroscopic data reveal that the ambidentate phosphoryl ligand is coordinated to the metal center in a bidentate manner via the phosphoryl and carbonyl oxygen atoms. The crystal and molecular structure of {Ln2L6-μ-(γ ,γ '-dipy)} has been determined by means of X-ray diffraction (triclinic, space group P i with parameters: a = 9.259(2), b = 12.530(3), c = 16.548(3) Å, α = 85.44(3)°, β = 75.64(3)°, γ = 70.56(3)°, Z = 1). The structure is made up of centrosymmetric binuclear molecules, in which the neutral heterocyclic ligand is coordinated to the metal centers in a bidentate bridging manner via its nitrogen atoms. The coordination number of each Lu(III) atom is 7 [60(L-) + N((γ ,γ '-dipy)]. Phosphoryl and carbonyl groups of the L- ligands are disposed in syn-position and are included in the six-membered chelate metallocycles. The coordination polyhedron of lutetium can be described as distorted mono-capped octahedron.

INFRARED SPECTRA OF 2,6-DIMETHYL-4-PYRONE COMPLEXES

1961 ◽  
Vol 39 (6) ◽  
pp. 1184-1189 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Complex Formation ◽  
Oxygen Atom ◽  
Carbonyl Group ◽  
Lewis Acid ◽  
Frequency Band ◽  
Infrared Spectra ◽  
Donor Site ◽  
Carbonyl Oxygen ◽  
Acid Strength ◽  
Group A

The infrared spectra of 2,6-dimethyl-4-pyrone in solution, and in complexes with HgCl2, ZnCl2, BF3, SbCl5, and HBr have been recorded. A band at 1639 cm−1 in the free pyrone moves to progressively lower frequencies in the complexes as the Lewis acid strength increases, identifying this band as the carbonyl stretching frequency and the donor site as the carbonyl group. A higher-frequency band, at 1678 cm−1 in the free pyrone, moves to lower frequency on complex formation, but to a much smaller extent, and is to be identified with a stretching mode of the ring. The site of protonation in 2,6-dimethyl-4-pyrone salts has been unequivocally shown to be the carbonyl oxygen atom.

Synthesis and Crystal Structure of [(CH2)6N4CH3]2[CoCl4]

2002 ◽  
Vol 55 (9) ◽  
pp. 561 ◽  
Author(s):  
W. Li ◽  
S.-L. Zheng ◽  
C.-R. Zhu ◽  
Y.-X. Tong ◽  
X.-M. Chen
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Title Complex ◽  
Chlorine Atoms ◽  
Synthesis And Crystal Structure ◽  
Methylene Groups ◽  
Self Assembled ◽  
Hydrogen Bonded

The interesting three-dimensional hydrogen-bonded self-assembled network of [(CH2)6N4CH3]+ cations and [CoCl4]2– anions has been prepared and structurally characterized. In the title complex, the quaternization of one hexamethylenetetramine nitrogen atom has been trapped, and further stabilized by the large [CoCl4]2– anions, featuring C–H���Cl hydrogen bonds (3.497–3.709 �) between the methylene groups of [(CH2)6N4CH3]+ cations and the chlorine atoms of the [CoCl4]2– anions.

A NUCLEAR MAGNETIC RESONANCE INVESTIGATION OF THE PROTONATION OF AMIDES IN FLUOROSULPHURIC ACID

1963 ◽  
Vol 41 (1) ◽  
pp. 148-155 ◽  
Author(s):  
R. J. Gillespie ◽  
T. Birchall
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Carbonyl Oxygen ◽  
Proton Resonance ◽  
Resonance Investigation ◽  
Nuclear Magnetic Resonance Investigation ◽  
Peak Areas ◽  
Magnetic Resonance Investigation

The proton resonance spectra of solutions of acetamide, N,N-dimethylacetamide, formamide, and N,N-dimethylformamide in fluorosulphuric acid have been studied at temperatures between 25° and −98°. At low temperatures a new peak appears in the spectra of solutions of all four compounds which is not present at room temperatures and which, from peak areas and other consideration, may be assigned with certainty to the [Formula: see text] group. It is thereby unambiguously established that these amides protonate on the carbonyl oxygen and not on the nitrogen atom.

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