PYRIDINE N-OXIDE COMPLEXES OF ZIRCONYL, THORIUM, AND URANYL PERCHLORATES

1964 ◽  
Vol 42 (4) ◽  
pp. 856-860 ◽  
Author(s):  
P. Rama Murthy ◽  
C. C. Patel
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Visible Region ◽  
Lone Pair ◽  
Vibrational Structure ◽  
Uranyl Complexes ◽  
Bond Character

Pyridine N-oxide complexes having the composition ZrO(Py•O)6(ClO4)2, Th(Py•O)8(ClO4)4, and UO2(Py•O)5(ClO4)2 have been prepared. The infrared and electronic absorption spectra show that the bonding between the metal and pyridine N-oxide in the complexes has occurred by donation of the lone pair of p-electrons on oxygen to the metal, and that the π-bond character of NO group increases in the complexes as uranyl < thorium < zirconyl. The decrease in the vibrational structure of the UO22+ spectrum in the visible region indicates strong coordination of pyridine N-oxide to the uranyl group. The decomposition temperatures of zirconyl, thorium, and uranyl complexes are 307, 350, and 319 °C respectively.

Spectroelectrochemical Study of some μ3-Oxo-μ-acetato Trinuclear Rhodium(III) and Iridium(III) Complexes

1995 ◽  
Vol 50 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Kenta Takahashi ◽  
Keisuke Umakoshi ◽  
Akihiro Kikuchi ◽  
Yoichi Sasaki ◽  
Masato Tominaga ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Visible Region ◽  
Absorption Bands ◽  
Visible Absorption ◽  
The One ◽  
Species Being

New trinuclear rhodium(III) complexes, [Rh3(μ3-O)(μ-CH3COO)6(L)3]+ (L = imidazole (Him), 1-methylimidazole (Meim), and 4-methylpyridine (Mepy)) have been prepared. The Him, Meim, and Mepy complexes show reversible one-electron oxidation waves at E1/2 = +1.12, +1.12, and +1.28 V vs Ag/AgCl, respectively, in acetonitrile. Electronic absorption spectra of the one electron oxidized species of these complexes and [Rh3(μ3-O)(μ-CH3COO)6(py)3]+ (py = pyridine) (E1/2 = +1.32 V ) were obtained by spectroelectrochemical techniques. While the Rh3(III,III,III) states show no strong visible absorption, the Rh3(III,III,IV ) species give a band at ca. 700 nm (ε = 3390-5540 mol dm-3 cm-1). [Ir3(μ3-O)(μ-CH3COO)6(py)3]+ with no strong absorption in the visible region, shows two reversible one-electron oxidation waves at +0.68 and +1.86 V in acetonitrile. The electronic absorption spectrum of the one-electron oxidized species (Ir3(III,III,IV )) also shows some absorption bands (688 nm (ε, 5119), 1093 (2325) and 1400 (ca. 1800)). It is suggested that the oxidation removes an electron from the fully occupied anti-bonding orbital based on metal-dπ-μ3-O-pπ interactions, the absorption bands of the (III,III,IV ) species being assigned to transitions to the anti-bonding orbital.

Intracavity Electronic Absorption Spectra of MoO and WO Molecules in the Visible Region

1997 ◽  
Vol 30 (6) ◽  
pp. 1057-1066 ◽  
Author(s):  
Yu. Ya. Kuzyakov ◽  
E. N. Moskvitina ◽  
E. N. Filippova
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Visible Region

Die Schwingungsfeinstruktur der elektronischen Absorptionsspektren von [OsO2(ox)2]2 -und [OsO2(mal)2]2-/ Vibrational Fine Structure on the Electronic Absorption Spectra of [OsO2(ox)2]2-and [OsO2(mal)2]2-

1983 ◽  
Vol 38 (2) ◽  
pp. 183-189 ◽  
Author(s):  
W. Preetz ◽  
H. Schulz
Keyword(s):  
Fine Structure ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Absorption Spectra ◽  
Point Group ◽  
Visible Region ◽  
Site Symmetry ◽  
Singlet Ground State ◽  
Ct Transitions

AbstractThe complexes (TBA)2[OsO2(ox)2] and (TBA)2[OsO2(mal)2] have been prepared and characterized. The IR and Raman frequencies are assigned according to point group D2h. The electronic absorption spectra measured on thin films of the solid complex salts on silica discs at 10 K show well resolved vibrational fine structure. Two very weak bands (ε: 4-58) in the visible region are assigned to d-d transitions from the singlet ground state ag2 (dxy) to a triplet and singlet term of the equivalent π* orbitals b2g/b3g (dxz, dyz). The two more intense band systems (ε: 500-1500) in the UV region are attributed to CT transitions from b2u/b3u π orbitals of the oxo ligands to the lowest unoccupied orbitals b2g/b3g of the central ion. These electronic transitions couple with vs(Os = O) as indicated by the main progression of about 700 cm-1 . In comparison to the vibrational ground state this lowered frequency is caused by population of antibonding π levels. The loosening of the Os = O bonds in the excited state is demonstrated by high anharmonic constants (-2.5 to -10.5 cm-1) and the estimated bond lengthening of about 12 pm. Moreover the vibrational fine structure of the malonato complex shows many combination modes of vs(Os = O) with other symmetric fundamentals. Due to lower site symmetry in the solid state the CT transitions of the malonato compound are split into 2 components with a spacing of about 200 cm-1 .

Stereochemistry of [carbonato-bis((S)-prolinato)]cobaltate(III) anion

1984 ◽  
Vol 49 (3) ◽  
pp. 680-683 ◽  
Author(s):  
Bohumil Hájek ◽  
Dagmar Sýkorová ◽  
Jiří Chyba
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Cd Spectra

The λ-C1-cis(N), δ-C1-cis(N), λ-C2-cis(N) and δ-C2-cis(N) isomers of the complex K[Co((S)-Pro)2CO3] were chromatographically separated and characterized by their electronic absorption spectra and CD spectra.

Photocolouration of 2,4,4,6-Tetraaryl-4H-pyrans and Their Heteroanalogues: Importance of Hypervalent Photoisomers

1995 ◽  
Vol 60 (10) ◽  
pp. 1621-1633 ◽  
Author(s):  
Stanislav Böhm ◽  
Mojmír Adamec ◽  
Stanislav Nešpůrek ◽  
Josef Kuthan
Keyword(s):  
Reaction Kinetics ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Theoretical Data ◽  
Order Reaction ◽  
Bleaching Process ◽  
First Order ◽  
Photodegradation Products ◽  
Hypervalent Molecules

Molecular geometries of 2,4,4,6-tetraphenyl-4H-pyran (Ia), 4,4-(biphenyl-2,2e-diyl)-2,6-diphenyl-4H-pyran (Ib) and their heterocyclic isomers II-V were optimized by the PM3 method and used for the calculation of electronic absorption spectra by the CNDO/S-CI procedure. Comparison of the theoretical data with experimental UV-VIS absorption spectra made possible to select hypervalent molecules IIIa, IIIb, IVa and IVb being responsible for the photocolouration of 4H-pyrans Ia, Ib, while compounds Va, Vb, VI and VII come into account as possible photodegradation products. The bleaching process of the UV illuminated compound Ia is analyzed in terms of dispersive first-order reaction kinetics.

Niobocene Dichloride and Niobocene Diiodide: Electronic Absorption Spectra and Electron Spin Resonance

1998 ◽  
Vol 63 (5) ◽  
pp. 628-635 ◽  
Author(s):  
Jana Holubová ◽  
Zdeněk Černošek ◽  
Ivan Pavlík
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Point Group ◽  
Esr Spectra ◽  
Ligand Field ◽  
Orbital Interaction ◽  
Symmetry Point Group ◽  
Spin Orbital ◽  
Halide Ligands

The effect of the halide ligand on the bonding of niobium in niobocene dichloride and niobocene diiodide was investigated. The electronic absorption spectra of the two compounds in the range of d-d transitions were resolved into four bands corresponding to transitions of the d1 electron between five frontier orbitals in a molecule of symmetry point group C2v. The energies of the frontier molecular orbitals were determined relatively to the energy of the orbitals in the spherically symmetric ligand field formed by the appropriate halide ligands. The effect of the halide ligands on the spin-orbital interaction of the HOMO orbital is discussed qualitatively on the basis the ESR spectra.

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