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.

INFRARED SPECTRA OF COMPLEXES OF 4-PYRIDONES

1963 ◽  
Vol 41 (2) ◽  
pp. 515-521 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Lewis Acid ◽  
Infrared Spectra ◽  
Lewis Acids ◽  
Donor Site ◽  
Acid Strength ◽  
Ring Mode ◽  
Lower Frequencies

The infrared spectra of many complexes of Lewis acids with some 4-pyridones have been recorded. Large shifts to lower frequencies of about 100 cm−1 have been observed in a band near 1560 cm−1 as the Lewis acid strength increased. Much smaller shifts of about 5 to 10 cm−1 in a band near 1640 cm−1 were noted. The former band has therefore been designated as the carbonyl frequency, and the latter as a ring mode involving CC stretching.The donor site of 4-pyridones is therefore the carbonyl group, and not the nitrogen atom. Protonated 4-pyridones have similar spectra, and are consistent with O-, not N-protonation.

INFRARED SPECTRA OF XANTHONE: LEWIS ACID COMPLEXES

1963 ◽  
Vol 41 (2) ◽  
pp. 522-526 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Lewis Acid ◽  
Lewis Acids ◽  
Quantitative Estimate ◽  
Donor Site ◽  
Carbonyl Oxygen ◽  
Acid Strength ◽  
Carbonyl Groups ◽  
Wide Range ◽  
Stretching Vibration ◽  
Solid Complexes

Xanthone, a member of the γ-pyrone species, which have basic carbonyl groups, forms an excellent series of solid complexes with Lewis acids. In these complexes the carbonyl oxygen atom is the donor site, and the carbonyl stretching vibration moves to progressively lower frequency as the Lewis acid strength increases. The carbonyl frequency in the BI3 complex, 1400 cm−1, is one of the lowest encountered in complexes of this type.The wide range of Lewis acids used to form these complexes has enabled a quantitative estimate of the Lewis acid strength to be made, which compares reasonably well with previous estimates.

2-Aminothiazole, acetylaminothiazole, dimethylhydantoin and thiohydantoin complexes of tin(IV) and titanium(IV) halides

1974 ◽  
Vol 27 (8) ◽  
pp. 1827 ◽  
Author(s):  
PP Singh ◽  
UP Shukla
Keyword(s):  
Infrared Spectra ◽  
Donor Site ◽  
Far Infrared ◽  
Carbonyl Oxygen ◽  
Spectral Studies ◽  
Infrared Spectral ◽  
Far Infrared Spectra

Complexes of the type MX4L2 (M = Sn, Ti; X = Cl, Br, I; L = dimethylhydantoin, thiohydantoin, 2-aminothiazole and 2-acetylaminothiazole) have been prepared and characterized. Infrared spectral studies indicate exocyclic nitrogen of 2:aminothiazole and carbonyl oxygen of all other ligands as the donor site. Far-infrared spectra suggest that dimethylhydantoin and 2-acetylaminothiazole complexes are trans, and 2-aminothiazole and thiohydantoin complexes are cis octahedral.

Host−Guest Chemistry of 1,2-Bis(chloromercurio)tetrafluorobenzene. Chelation of the Carbonyl Oxygen Atom of Acetone by a Bidentate Lewis Acid

1999 ◽  
Vol 18 (9) ◽  
pp. 1747-1753 ◽  
Author(s):  
Martin Tschinkl ◽  
Annette Schier ◽  
Jürgen Riede ◽  
François P. Gabbaï
Keyword(s):  
Oxygen Atom ◽  
Lewis Acid ◽  
Carbonyl Oxygen ◽  
Carbonyl Oxygen Atom ◽  
Guest Chemistry

Structure of donor-acceptor complexes. X. Complexes of cyanoacetamide with Lewis acids

1969 ◽  
Vol 22 (7) ◽  
pp. 1381 ◽  
Author(s):  
RC Paul ◽  
SL Chadha
Keyword(s):  
Oxygen Atom ◽  
Spectral Data ◽  
Infrared Spectra ◽  
Lewis Acids ◽  
Far Infrared ◽  
Carbonyl Oxygen ◽  
Aluminium Chloride ◽  
Infrared Spectral ◽  
Donor Acceptor ◽  
Ionic Nature

Complexes of cyanoacetamide with aluminium chloride and bromide, anti- mony(V) chloride, boron(III) bromide, tin(IV) chloride and bromide, titanium(IV) chloride and bromide, and zirconium(IV) chloride have been prepared. The molar conductances of the complexes in nitrobenzene indicate their non-ionic nature. The infrared spectra indicate bonding of the metal halides to the carbonyl oxygen atom of the ligand. Metal- to-oxygen bonding also gets support from the far-infrared spectral data.

Quadruple Coordination of the Carbonyl Oxygen Atom of an Amide by a Cyclic Tetradentate Lewis Acid

1998 ◽  
Vol 17 (6) ◽  
pp. 1215-1219 ◽  
Author(s):  
Jean Vaugeois ◽  
Michel Simard ◽  
James D. Wuest
Keyword(s):  
Oxygen Atom ◽  
Lewis Acid ◽  
Carbonyl Oxygen ◽  
Carbonyl Oxygen Atom

α-PYRIDONE COMPLEXES AND THEIR INFRARED SPECTRA

1965 ◽  
Vol 43 (4) ◽  
pp. 741-748 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Complex Formation ◽  
Carbonyl Group ◽  
Infrared Spectra ◽  
Lewis Acids ◽  
Lewis Acidity

The infrared spectra of complexes of 1-methyl-2-pyridone and 1-methyl-2-quinolone with Lewis acids are consistent with interaction at the carbonyl group. The stretching frequency of this group, vco, is lowered on complex formation, the change being proportional to the Lewis acidity. Two other bands, at 1 670 and 1 380 cm−1 move to lower frequency in much smaller steps and are associated with ring modes.

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.

Beta—tricalcium phosphate as a substitute for autograft in interbody fusion cages in the canine lumbar spine

2002 ◽  
Vol 97 (3) ◽  
pp. 350-354 ◽  
Author(s):  
Takashiro Ohyama ◽  
Yoshichika Kubo ◽  
Hiroo Iwata ◽  
Waro Taki
Keyword(s):  
Lumbar Spine ◽  
Tricalcium Phosphate ◽  
Interbody Fusion ◽  
Donor Site ◽  
Posterolateral Approach ◽  
Content Type ◽  
Spine Model ◽  
Group A ◽  
Group B ◽  
Fine Print

Object. An interbody fusion cage has been introduced for cervical anterior interbody fusion. Autogenetic bone is packed into the cage to increase the rate of union between adjacent vertebral bodies. Thus, donor site—related complications can still occur. In this study a synthetic ceramic, β—tricalcium phosphate (TCP), was examined as a substitute for autograft bone in a canine lumbar spine model. Methods. In 12 dogs L-1 to L-4 vertebrae were exposed via a posterolateral approach, and discectomy and placement of interbody fusion cages were performed at two intervertebral disc spaces. One cage was filled with autograft (Group A) and the other with TCP (Group B). The lumbar spine was excised at 16 weeks postsurgery, and biomechanical, microradiographic, and histological examinations were performed. Both the microradiographic and histological examinations revealed that fusion occurred in five (41.7%) of 12 operations performed in Group A and in six (50%) of 12 operations performed in Group B. The mean percentage of trabecular bone area in the cages was 54.6% in Group A and 53.8% in Group B. There were no significant intergroup differences in functional unit stiffness. Conclusions. Good histological and biomechanical results were obtained for TCP-filled interbody fusion cages. The results were comparable with those obtained using autograft-filled cages, suggesting that there is no need to harvest iliac bone or to use allo- or xenografts to increase the interlocking strength between the cage and vertebral bone to achieve anterior cervical interbody fusion.

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