Mozaffar Asadi

ABSTRACT Substitution reactions of a Cl− ligand in [SnCl2(tpp)] (tpp=5,10,15,20-tetraphenyl-21H,23H-porphinato(2−)) by five organic bases i.e., butylamine (BuNH2), sec-butylamine (sBuNH2), tert-butylamine (tBuNH2), dibutylamine (Bu2NH), and tributylamine (Bu3N), as entering nucleophile in dimethylformamide at I=0.1M (NaNO3) and 30–55° were studied. The second-order rate constants for the substitution of a Cl− ligand were found to be (36.86±1.14)⋅10−3, (32.91±0.79)⋅10−3, (22.21±0.58)⋅10−3, (19.09±0.66)⋅10−3, and (1.36±0.08)⋅10−3 M−1s−1 at 40° for BuNH2, tBuNH2, sBuNH2, Bu2NH, and Bu3N, respectively. In a temperature-dependence study, the activation parameters ΔH≠ and ΔS≠ for the reaction of [SnCl2(tpp)] with the organic bases were determined as 38.61±4.79 kJ mol−1 and −150.40±15.46 J K−1mol−1 for BuNH2, 40.95±4.79 kJ mol−1 and −143.75±15.46 J K−1mol−1 for tBuNH2, 30.88±2.43 kJ mol−1 and −179.00±7.82 J K−1mol−1 for sBuNH2, 26.56±2.97 kJ mol−1 and −194.05±9.39 J K−1mol−1 for Bu2NH, and 39.37±2.25 kJ mol−1 and −174.68±7.07 J K−1 mol−1 for Bu3N. From the linear rate dependence on the concentration of the bases, the span of k2 values, and the large negative values of the activation entropy, an associative (A) mechanism is deduced for the ligand substitution.

Some oxovanadium(IV) complexes, namely bis(1,1,1-trifluro-2,4-pentanedionato-O,O′) oxovanadium (IV), [VO(tfac)2(H2O)], bis(1-phenyl-2,4-pentanedionato-O,O′)oxovanadium(IV), [VO(phac)2(H2O)], bis(1,3-diphenyl-2,4-pentanedionato-O,O′)oxovanadium(IV), [VO(dphac)2 (H2O)], of the type [VO(O4)] and bis(pyrolidineaniline)oxovanadium(IV), [VO(pyran)2(H2O)], bis(p-hydroxypyrolidineaniline) oxovanadium(IV), [VO(p-hydroxypyran)2(H2O)], bis(p-methoxypyrolidineaniline) oxovanadium(IV), [VO(p-MeOpyran)2 (H2O)], bis(p-chloropyrolidineaniline)oxovanadium(IV), [VO(p-chloropyran)2(H2O)], bis(p-bromopyrolidineaniline)oxovanadium(IV), [VO(p-bromopyran)2(H2O)], bis(p-cyano pyrolidineaniline)oxovanadium(IV), [VO(p-cyanopyran)2(H2O)], and bis(pyrolidinebenzylamine) oxovanadium(IV), [VO(pyrbz)2(H2O)], of the type [VO(N4)] were synthesized and characterized by IR, UV-Vis, mass spectrometry, elemental analysis, magnetic moment and thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. The number of steps and, in particular, the starting temperature of decomposition of these complexes depends on the equatorial ligand. Also, formation constants of the complexes have been determined by UV-Vis absorption spectroscopy through titration of the ligands with the metal ions at constant ionic strength (0.1 M NaClO4) and at 25°C. According to the thermodynamic studies, as the steric character of the ligand increases, the complexation tendency to VO(IV) center decreases. Also, the ab initio calculations were carried out to determine the structural and the geometrical properties of the complexes.

ABSTRACT A set of two Cu(II) complexes, [Cu(cdXsalen)] and [Cu(cdXsalMeen)] derived from Schiff base ligands (H2cdXsalen: methyl-2-{[2-(2-X-phenyl)methylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate and H2cdXsalMeen: methyl-2-{[1-methyl-2-(2-X-phenyl)methylidynenitrilo]ethyl}amino-1-cyclopenteneithiocarb-oxylate where X = hydroxyl, methoxy, nitro, sodiumsulfite, chloro, bromo and H2cdMesalen: methyl-2-{[2-(2-hydroxyphenyl)ethylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H2cdPhsalen: methyl-2-{[2-(2-hydroxyphenyl)phenylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H2cdMesalMeen: methyl-2-{[1-methyl-2-(2-hydroxyphenyl)ethylidynenitrilo]ethyl}amino-1-cyclopentenedithiocarboxylate; H2cdPhsalMeen: methyl-2-{[1-methyl-2-(2-hydroxyphenyl)phenylidynenitrilo]ethyl}amino-1-cyclopentenedi-thiocarboxylate) with an unsymmetric NNOS coordination sphere have been synthesized and characterized by elemental analysis, IR, UV-Vis and mass spectrometry. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at constant ionic strength 0.1 M (NaClO4), at 25 °C in DMF solvent. The trend of the complex formation for copper is as follow: [Cu(cdMesalen)] > [Cu(cdsalen)] > [Cu(cdPhsalen)] [Cu(cdMesalMeen)] > [Cu(cdsalMeen)] > [Cu(cdPhsalMeen)] and [Cu(cd5OMesalen)] > [Cu(cd3OMesalen)] > [Cu(cd4OMesalen)] [Cu(cd5OMesalMeen)] > [Cu(cd3OMesalMeen)] > [Cu(cd4OMesalMeen)] and [Cu(cd5OMesalen)] > [Cu(cdsalen)] > [Cu(cd5Brsalen)] > [Cu(cd5Clsalen)] > [Cu(cd5NO2 salen)] > [Cu(cd5SO3 Nasalen)] [Cu(cd5OMesalMeen)] > [Cu(cdsalMeen)] > [Cu(cd5BrsalMeen)] > [Cu(cd5ClsalMeen)] > [Cu(cd5NO2 salMeen)] > [Cu(cd5SO3 NasalMeen)] and [Cu (cdXsalMeen > [Cu (cdXsalen)] . The structure of {methyl-2-[N-[2-(5-chloro-2-phenolate)methylidynenitrilo]ethyl}aminato(-1)-1-cyclopentene-dithiocarboxylatecopper(II), [Cu(cd5Clsalen)], has been determined by X-ray crystallography. The complex shows normal planar geometry around the copper center.

ABSTRACT The equilibrium quotient of the adduct formation of [Co(Salen)PPh3]ClO4.H2O and [Co(7,7'-dimethylSalen)PPh3]ClO4.H2O, as acceptor with amines donors are studied by spectrophotometer. Thermodynamics of these pentacoordinate cobalt(III) Schiff-base complexes have been examined with n-butylamine, sec-butylamine, tert-butylamine, benzylamine and diethylamine in constant ionic strength of 0.1 M sodium perchlorate and acetonitrile solvent at room temperature. We aimed to investigate the effects of different electronic and steric situations of donor and acceptor by comparing their equilibrium quotient for any adduct.

A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L(1)-L(4)), were synthesized and characterized by FT-IR, UV-vis and elemental analysis. The structure of the complex VOL(1)⋅DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the "-yl" oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO<H<Br<Cl. We also studied the thermodynamics of formation of the complexes and kinetic aspects of their thermal decomposition. The formation constants with various substituents on the aldehyde ring follow the trend 5-OMe>5-H>5-Br>5-Cl. Furthermore, the kinetic paramet...

... 1157 Abedien Zabardasti †*, Mozaffar Asadi †† and Ali Kakanejadifard † ... Pyrrole (10 mmoles) was added and the mixture was kept at 120°C during 1 hour. On cooling, the porphyrin precipitated directly from the reaction mixture and was isolated by filtration. Adduct Formations. ...

... CHEN, Jingtaoa,b(陈经涛) HE, Donghuab(何东华) DI, Youying*,b(邸友莹) KONG, Yuxiab(孔玉霞) YANG, Weiweib(杨伟伟) DAN, Wenyanb(淡文彦) TAN ... A new third adiabatic shield was added, the sample cell was surrounded in turn by inner, middle and outer adia-batic shields ...

Page 1. Archive of SID J. Iran. Chem. Soc., Vol. 7, No. 4, December 2010, pp. ... EXPERIMENTAL Materials All solvents and chemicals were purchased from Merck, Fluka or Aldrich and used without further purification. www.SID.ir Page 2. Archive of SID Asadi et al. 1022 ...