Otilia Costisor

Metal mediated template synthesis of ligands

Template Effect Self-Condensation of Nitriles Schiff Condensation Mannich Condensation Alkylation Reactions Self-Assembled Systems

Synthesis, crystal structure and magnetic properties of [Cu(bipy)2(CH3COO)][Cu(bipy)2(Cr(C2O4)3)]·∼10.5H2O, the first compound containing the [Cr(C2O4)3]3− building block acting as a monodentate ligand

Abstract The reaction between copper(II) acetate with 2,2′-bipyridine and K3[Cr(C2O4)3] leads to the novel salt [Cu(bipy)2(CH3COO)][Cu(bipy)2(Cr(C2O4)3)]·∼10.5H2O, 1 (bipy=2,2′-bipyridine). The crystal structure of 1 consists of mononuclear cationic species [Cu(bipy)2(CH3COO)]+ and heterobinuclear anionic units, [Cu(bipy)2(Cr(C2O4)3)]−. The tris-oxalato-chromium entity behaves as a monodentate ligand toward the copper(II) ion within the complex anion. The distance between Cr(III) and Cu(II) across the bridging oxalato group is 5.056(2) A. The copper(II) ions exhibit a distorted trigonal bipyramidal surrounding in both cationic and anionic species. The π–π stacking interaction between bipy ligands of the neighboring [Cu(bipy)2(CH3COO)]+ mononuclear entities leads to chains of copper atoms running along the b axis. Magnetic susceptibility measurements of 1 in the temperature range of 1.9–290 K reveal a quasi-Curie law behavior, the magnetic coupling between Cr(III) and Cu(II) through the bridging oxalato group with the bidentate/monodentate coordination mode being negligible.

METAL DIRECTED MANNICH SYNTHESIS OF LIGANDS

This paper reviews ligands obtained by metal directed Mannich condensation. The condensation of the c/s-disposed coordinated amines with formaldehyde and an acid component, like ammonia, alkyl amine, nitroalkanes, malonic acid esters, phosphine, or arsine give rise to acyclic, cyclic or polycyclic cage ligands depending strongly on the nature of the metal ion, on the stability of the metal ion precursor as well as on the experimental condition. The changes induced by this capping reaction comparing to their parent precursors are discussed in detail. ABSTRACT

Recent Developments in the Coordination Chemistry Of Antipyrine and Antipyrine Derivatives

This paper reviews the coordination architectures obtained when antipyrine and their derivatives act as ligands towards metal ions along with a description of their general particularities. The work is organised roughly by along the ligands nature. The sStructural particularities as well as some specific properties are discussed in detail.

ON VANADIUM SULFUR CHEMISTRY

This paper reviews the compounds containing vanadium-sulfur bonds: binary and ternary vanadium sulfides, as well as mononuclear and polynuclear vanadium complexes with ligands containing sulfur atoms as donors. The structural and spectral particularities as well as some specific properties are discussed in detail.

Mixed-Ligand Complexes of Co(II) and Cu(II) with Pyrazoeon1C Mannich Bases and 2-aminobenzothiazole

Abstract Mixed-ligand complexes of the type M2L(TAB)nX4 [L = N,N′-bis(4-antipyryl-methyl)piperazine (BAMP), or N,N′-tetra(4-antipyrylmethyl)-l,2-diaminoethane (TAMEN) and 2-aminobenzothiazole (TAB), X - NCS or CIO4, M - Co, n - 2, or M - Cu, n = 4] were synthesized and investigated. The IR and Raman spectra revealed that the ligands L are coordinated through the carbonyl oxygen atom of the antipyrine and the nitrogen atom of the piperazine or 1,2-ethanediaminc bridge, except in Cu2(TAMEN)(TAB)4(ClO4)4, in which case TAMKN is coordinated to the metal only through the carbonyl oxygen. Steric considerations explain the bonding of TAB through the exocyclic or endocyclic nitrogen.

Chemistry and Photochemistry of 2,6-Bis(2-hydroxybenzilidene)cyclohexanone. An Example of a Compound Following the Anthocyanins Network of Chemical Reactions

The kinetics and thermodynamics of the 2,6-bis(2-hydroxybenzilidene)cyclohexanone chemical reactions network was studied at different pH values using NMR, UV-vis, continuous irradiation, and flash photolysis. The chemical behavior of the system partially resembles anthocyanins and their analogue compounds. 2,6-Bis(2-hydroxybenzilidene)cyclohexanone exhibits a slow color change from yellow to red styrylflavylium under extreme acidic conditions. The rate constant for this process (5 × 10(-5) s(-1)) is pH independent and controlled by the cis-trans isomerization barrier. However, the interesting feature is the appearance of the colorless compound, 7,8-dihydro-6H-chromeno[3,2-d]xanthene, isolated from solutions of acid to neutral range, characterized by (1)H NMR and single crystal X-ray diffraction. Light absorption by 2,6-bis(2-hydroxybenzilidene)cyclohexanone solutions immediately after preparation exclusively results in cis-isomer as photoproduct, which via hemiketal formation yields (i) red styrylflavylium by dehydration under extremely acidic solutions (pH < 1) and (ii) colorless 7,8-dihydro-6H-chromeno[3,2-d]xanthene by cyclization in solutions of acid to neutral range.

4f AND 5f METAL ION DIRECTED SCHIFF CONDENSATION

The paper reviews the ability of 4f and 5f metal ions to direct Schiff base condensation. The structural particularities as well as some particularities of the resulted systems are discussed in detail. K e y w o r d s : Lanthanide, actinide, template; complexes; Schiff bases.

Mixed-ligand complexes of iron(II), iron(III), copper(II), and cobalt(II) with pyrazolonic and 2,2′-bipyridine ligands

New mixed-ligand complexes, [M2(BAMP)(bipy)2][MCl4]2, M=Co+2(1), Cu+2(2), [M2(TAMEN)(bipy)2][MCl4]2, M=Fe+2(3), Co2+(4), and [Fe2(TAMEN)(bipy)2][FeCl6]2 (5), where BAMP and TAMEN stand for the Mannich bases N,N′-bis(antipyryl-4-methylene)-piperazine and N,N′-tetra(antipyryl-4-methylene)-1,2-ethane-diamine, respectively, have been obtained and characterized by elemental analyses, conductometric and magnetic susceptibility measurements at room temperature, mass spectrometry, UV-Vis, infrared, and mass spectroscopy, and 1H NMR spectra for the ligands.

New Compounds with Potential Liquid Crystal Properties. Copper(II) and Nickel(II) Complexes of N,N′-bis(4-decyloxysalicyliden-N-n-propyl)-Piperazine. Synthesis and Characterization

The new Schiff base N,N′-bis(4-decyloxysalicyliden-N-n-propyl)-piperazine (ZOPP) was designed and synthesized. Structures were confirmed by elemental analysis and IR, 1H-NMR spectroscopy. ZOPP can act as ligand through the two set of donor atoms (one set: two nitrogen atoms and one oxygen) situated on each side of the piperazine bridge. The nature of the complexes depends strongly on the metal to ligand molar ratio. Thus, starting from metal to ligand of 1 to 1 ratio, where M=Cu(II), Ni(II), binuclear complexes with a polymeric structure have been obtained, whereas at metal to ligand molar ratio of 2 to 1, discrete binuclear complexes were formed.