E.M. Nour

Electronic spectral studies and solvent effects on the reaction of iodine with 1,4,8,11-tetraazacyclotetradecane

Abstract The reaction between iodine and 1,4,8,11-tetraazacyclotetradecane (TACTD) is studied photometrically in various solvents like CCl 4 , CHCl 3 , CH 2 Cl 2 and 1,2-dichloroethane. The results reveal that in each solvent the (TACTD):I 2 ratio is 1:2 and the iodine complex is formulated as (TACTD)I + ·I 3 − . The obtained values of the formation constant ( K ), extinction coefficient (e) and oscillator strength (ƒ) for the iodine complex are shown to be strongly dependent on the polarity of the solvent. A linear correlation is obtained between either (ƒ) or (e) and the dielectric constant ( D ) of the solvent. The important role of the solvent is mainly suggested to be due to the interaction of the ionic iodine complex with the solvent.

Resonance Raman study of the polyiodide complex formed in the reaction of iodine with the polysulphur cyclic base 1,4,7,10,13,16-hexathiacyclooctadecane.

Resonance Raman spectroscopy has been used to study the reaction of iodine with the interesting polysulphur cyclic base, 1,4,7,10,13,16,-haxathiacyclootadecane (HTCOD). The results indicate that the complex [(HTCOD)2]+ x I5- is formed. The I5- unit exists in the form of distorted I2 linked to I3- unit which has two unequivalent I-I bonds. The v(I-I) for I2 occurs at 194 cm(-1) while for I-I, inner and outer bonds in I3- at 143 and 160 cm(-1), respectively.

Spectroscopic studies on the reaction of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane

Abstract The interaction of iodine with the nitrogen cyclic base 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMTACTD) is studied spectrophotometrically in CHCl 3 and the resonance Raman spectrum of the solid product is recorded. The results indicate the formation of the polyiodide species with the formula [(TMTACTD)I] + . I 9 − . The resonance Raman spectrum of the product suggests that the enneaiodide, I 9 − , does indeed contain the I 5 unit and this implies that I 9 − exists as (I 5 − ) (2I 2 ) where the I 5 − portion has a bent configuration with C 2 ν symmetry. All bond vibrations for the I 5 and I 2 units are observed and assigned.

Spectroscopic Studies of the Reactions of π-Electron Acceptors with the Cyclic Polyamine 1,4,8,11-Tetraazacyclotetradecane

Abstract The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7,7′,8,8′-tetracyanoquino-dimethane (TCNQ), tetrachloro-p-benzoquinone (chloranil) and tetra-cyanoethylene (TCNE) with the cyclic polyamine base 1,4,8,11-tetraazacyclotetradecane (TACTD) have been investigated in CHCl3 solvent. The data indicate the formation of the CT-complexes with the general formula [(TACTD) (acceptor)2]. The 1: 2 stoichiometry of the (TACTD)-acceptor was based on elemental analysis and infrared spectra of the solid CT-complexes along with the photometric titration curves for the reactions in CHCl3. The formation constants (K) for the CT-complexes are shown to be strongly dependent on the type and structure of the acceptor.

Preparation and infrared spectrum of the bridged diacetato complex [Cu2(O)(H2O)2(OOCCH3)2 formed by the reaction of urea with copper (II) acetate

Abstract The bridged diacetato complex [Cu2(O)(H2O)2(OOCCH3)2] has been obtained by reacting aqueous solutions of Cu(OOCCH3)2 · H2O and urea at about 70°C. The reaction product was characterized through elemental analysis and i.r. measurements. The i.r. spectrum shows the characteristic bands of coordinated acetate ions and water, and was interpreted on the basis of C2v symmetry for the complex. A general mechanism describing the formation of [Cu2(O)(H2O)2(OOCCH3)2] is proposed.

Synthesis and Vibrational Studies of Oxovanadium (IV) - Tetradentate Schiff Base Complexes

Abstract The two new Schiff base complexes of oxovanadium (IV) [VO(acac-en)] (acac-en = bisacetylactone-ethylenediimino) and [VO(sal-o-phdn)] (sal-o-phdn = N,N′-o-phenylenebis (salicylideneiminato) have been prepared. The infrared spectra of the solid complexes have been obtained and assigned on the bases of Cs symmetry. A polymeric chain structure with V-O-V bridge has been adopted for the both complexes.

Raman and infrared studies of the NbF5O2−2 ion

Abstract The Raman and i.r. spectra of the NbF 5 O 2− 2 ion have been investigated. The observed bands are assigned on the basis of C 2ν symmetry. The ν(OO), ν s (NbO) and ν as (NbO) stretching frequencies are observed at 955, 880 and 900 cm −1 , respectively.

Spectroscopic and thermal studies on the diperoxo-citrato complex K2[MoO(O2)2(O7C6H6)] · 12H2O2 · 3H2O

Abstract The i.r. spectrum of the diperoxo-citrato complex K 2 [MoO(O 2 ) 2 (O 7 C 6 H 6 )] · 1 2 H 2 O 2 · 3H 2 O has been recorded and the observed bands are assigned on the basis that the ion (MoO(O 2 )(O 7 C 6 H 6 )) 2− has C 1 symmetry while the oxo-diperoxo unit, MoO(O 2 ) 2 , has local symmetry C 2 . The v s (O-O) and v as (O-O) frequencies are observed to be 910 and 875 cm −1 , respectively, while v as (Mo-O) and v s (Mo-O) (O of O 2− 2 ) are assigned at 585 and 560 cm −1 , respectively. The corresponding v (Mo-O) for the O of the citrate group are assigned at 520 and 498 cm −1 , and v (Mo=O) is observed at 945cm −1 . The electronic absorption spectrum of the diperoxo-citrato complex shows one band at 320 nm assigned to a charge-transfer of the type O 2− 2 → Mo 6+ . Thermogravimetric (TG) and differential thermal analysis (DTA) measurements on the complex were also carried out. The data obtained agree quite well with its expected structure and show that the complex finally decomposes to form K 2 MoO 4 . A detailed mechanism for the complex thermal decomposition is given and the activation energies for the bonds are calculated.