The reaction of Pb(CH3COO)2·3H2O with N-benzesulfonyl-L-glutamic acid in the presence of 2, 2′-bipyridine (bipy) or 1,10-phenanthroline (phen) produced two novel complexes [Pb2(Bs-glu)2(bipy)2] (1) and [Pb2(Bs-glu)2(phen)2] (2) (Bs-glu = N-benzesulfonyl-L-glutamic acid dianion). In 1 chains bearing alternative 16-membered rings and Pb2O3 nodes are constructed from the interactions of PbII ions with the carboxylates of Bs-glu ligands. To the best of our knowledge, this is the first lead(II) complex of carboxylates with the formation of chains of Pb2O3. In 2 the 16-membered ring units are connected by centrosymmetric Pb2O2 nodes to form chains. Complexes 1 and 2 construct the 3-D supramolecular architectures through versatile hydrogen bonds and π-π stacking interactions.

Two Novel Three-Dimensional Lead(II) Coordination Polymers Involving 16-Membered Rings: [Pb2(Bs-glu)2(bipy)2] and [Pb2(Bs-glu)2(phen)2]

Synthesis, crystal structure, spectral and DFT studies of potent isatin derived metal complexes

Two new Schiff and Mannich bases, namely, 1-Morpholinomethyl-3(1′ -N-dithiooxamide)iminoisatin (LIH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)iminoisatin (LIIH), were prepared from condensation reaction of new Schiff base 3-(1′-N-dithiooxamide)iminoisatin (SBH) with morpholine or diphenylamine respectively in presence of formaldehyde . The structures were characterized by IR, 1HNMR, mass spectrometry, and CHN analyses. Metal complexes of the two ligands were synthesized, and their structures were characterized by elemental analyses, atomic absorption, IR and UV-visible spectra, molar conductivity, and magnetic moment determination. All complexes showed octahedral geometries except palladium complexes which were square planar. The biological activity of the prepared compounds and some selected metal complexes was tested against three types of bacteria and against cell line of human epidermoid larynx carcinoma (Hep-2).

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Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide

A series of 1D coordination polymers [Co(m-dtab)Cl2]n (1), [Co(m-dtab)Br2]n (2) and [Ni(m-dtab)2(Br)2]n (3), where m-dtab = the dithioamide of 1,3-benzenedicarboxylic acid, were prepared. The structures of all complexes were determined by X-ray diffraction. Magnetic properties of the compounds were characterized by molecular susceptibility vs. T dependence in the temperature range from 2 to 300 K. All compounds possess antiferromagnetic exchange interactions, and antiferromagnetic ordering was found in [Co(m-dtab)Br2]n and [Ni(m-dtab)2Br2]n at TN = 2.9 K and 2.6 K, respectively. DFT calculations showed that exchange interactions in [Co(m-dtab)(Hal)2]n could be transferred through two pathways: m-dtab between metal ions or interchain π–π stacking of aromatic rings, so the systems are not 1D from the viewpoint of magnetochemistry. The results of DFT calculations are consistent with the existence of magnetic ordering.

Antiferromagnetic ordering in cobalt(II) and nickel(II) 1D coordination polymers with the dithioamide of 1,3-benzenedicarboxylic acid

The reaction of [Rh(2-phenylpyridine) 2 Cl] 2 with secondary dithiooxamides H 2 R 2 C 2 N 2 S 2 (R = isoamyl, isopropyl, {S}-phenylethyl, meso-phenylethyl) affords the contact ion pair [Rh(2-phenylpyridine) 2 (H 2 R 2 C 2 N 2 S 2 κ-S,S-Rh)] + Cl ― , which can be transformed into the neutral complexes [Rh(2-phenylpyridine) 2 (HR 2 C 2 N 2 S 2 κ-S,S-Rh)]. The HCl exchange between the ion pairs and the corresponding neutral complexes has been studied by means of dynamic NMR spectroscopy techniques, and a mechanism for this exchange has been proposed. [Rh(2-phenylpyridine) 2 {H(isoamyl) 2 C 2 N 2 S 2 κ-S,S-Rh}] reacts with chlorido-bridged dimers [ML n Cl] 2 {ML n = Pd(η 3 -allyl), Rh(cyclooctadiene), (n-propyl) 3 PClPd} and provides the heterobimetallic complexes [Rh(2-phenylpyridine) 2 -{μ-(isoamyl)C 2 N 2 S 2 }ML n ]. Heterobimetallic complexes having the same formula and the same structure are obtained by reaction of [ML n {H(isoamyl) 2 C 2 N 2 S 2 κ-S,S-M}] species [ML n = Rh(1,5-cyclooctadiene), Pd(η 3 -allyl), PdCl(tri-n-propyl-phosphane), PtCl(diphenyl-2-pyridylphosphane)] with [Rh(2-phenylpyridine) 2 Cl] 2 . The connectivity of the binucleating ligand diisoamyldithiooxamidate within the bimetallic complexes has been assessed. The linkage isomer obtained is [Rh(2-phenylpyridine) 2 {μ-(isoamyl)C 2 N 2 S 2 }ML n ] (κ-N,N-Rh III , κ-S,S-M).

Metalloligands: Rhodium(III) Cyclometallated Compounds Containing Multitopological Binucleating Ligands

New dinuclear complexes of the types [Ni2(L)-(H2O)2] and [Ni2(L)(H2O)6] [H4L = N,N′-bis(carboxymethyl) dithiooxamide (H4GLYDTO), N,N′-bis(1-carboxyethyl) dithiooxamide (H4ALADTO), N,N′-bis(1-carboxy-2-methylpropyl) dithiooxamide (H4VALDTO) and N,N′-bis-(1-carboxy-3-methylbutyl) dithiooxamide (H4LEUDTO)] have been prepared and characterized by IR and electronic absorption spectroscopy, and the structure of [Ni2(ALADTO)-(H2O)6] crystals has been determined by single crystal X-ray analysis. This compound is composed of discrete dinuclear units in which two NiII atoms with NO4S kernels are linked by a single [ALADTO]4- group that coordinates through its carboxylato oxygen, amino nitrogen and thiolato sulphur atoms. In each dimer unit the two nickel(II) ions in distorted octahedral coordination are separated by 5.863(2) A The temperature dependence of the magnetic susceptibility of the new compounds was measured over the range 2 to 300 K. In the complexes of [GLYDTO]4- and [ALADTO]4- the two Ni atoms are antiferromagnetically coupled, with J = -23.51(4) and -20.95(8) cm-1, respectively. By constrast, [Ni2(VALDTO)(H2O)2], [Ni2(VALDTO)(H2O)6] and [Ni2-(LEUDTO)(H2O)2] remain paramagnetic down to 2 K, with magnetic moment values between 2.8 and 3.3 M.B. © WILEY-VCH Verlag GmbH, 2001.

J. M. Tercero

Papers

Synthesis, characterization, and magnetic behaviour of dinuclear nickel(II) complexes of N,N′-substituted dithiooxamides derived from α-amino acids