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Two new ligands, 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol (HL) and 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methyl-6-(methylthio)phenol (HSL), were synthesized and were used to prepare the trinuclear copper(II) complex {[CuSL(Cl)]2Cu}(PF6)2.H2O (1) and the corresponding binuclear complexes [Cu2(SL)2](PF6)2 (2) and [Cu2L2](PF6)2 (3). The crystal structure of 1 shows two different coordination environments: two square base pyramidal centers (Cu1 and Cu1a, related by a C2 axes), acting as ligands of a distorted square planar copper center (Cu2) by means of the sulfur atom of the SCH3 substituent and the bridging phenoxo oxygen atom of the ligand (Cu2-S = 2.294 A). Compounds 2 and 3 show two equivalent distorted square base pyramidal copper(II) centers, bridged in an axial-equatorial fashion by two phenoxo groups, thus defining an asymmetric Cu2O2 core. A long copper-sulfur distance measured in 2 (2.9261(18) A) suggests a weak bonding interaction. This interaction induces a torsion angle between the methylthio group and the phenoxo plane resulting in a dihedral angle of 41.4(5) degrees. A still larger distortion is observed in 1 with a dihedral angle of 74.0(6) degrees. DFT calculations for 1 gave a ferromagnetic exchange between first neighbors interaction, the calculated J value for this interaction being +11.7 cm-1. In addition, an antiferromagnetic exchange for 1 was obtained for the second neighbor interaction with a J value of -0.05 cm-1. The Bleaney-Bowers equation was used to fit the experimental magnetic susceptibility data for 2 and 3; the best fit was obtained with J values of +3.4 and -16.7 cm-1, respectively. DFT calculations for 2 and 3 confirm the nature and the values of the J constants obtained by the fit of the experimental data. ESR and magnetic studies on the reported compounds show a weak exchange interaction between the copper(II) centers. The low values obtained for the coupling constants can be explained in terms of a poor overlap between the magnetic orbitals, due to the axial-equatorial phenoxo bridging mode observed in these complexes.

The palladium(II) bis-chelate complexes of the type [Pd(TSC1-5)2] (6–10), with their corresponding ligands 4-phenyl-1-(acetone)-thiosemicarbazone, HTSC1 (1), 4-phenyl-1-(2′-chloro-benzaldehyde)-thiosemicarbazone, HTSC2 (2), 4-phenyl-1-(3′-hydroxy-benzaldehyde)-thiosemicarbazone, HTSC3 (3), 4-phenyl-1-(2′-naphthaldehyde)-thiosemicarbazone, HTSC4 (4), and 4-phenyl-1-(1′-nitro-2′-naphthaldehyde)-thiosemicarbazone, HTSC5 (5), were synthesized and characterized by elemental analysis and spectroscopic techniques (IR and 1H- and 13C-NMR). The molecular structure of HTSC3, HTSC4, and [Pd(TSC1)2] (6) have been determined by single crystal X-ray crystallography. Complex 6 shows a square planar geometry with two deprotonated ligands coordinated to PdII through the azomethine nitrogen and thione sulfur atoms in a cis arrangement. The in vitro cytotoxic activity measurements indicate that the palladium(II) complexes (IC50 = 0.01–9.87 μM) exhibited higher antiproliferative activity than their free ligands (IC50 = 23.48–70.86 and >250 μM) against different types of human tumor cell lines. Among all the studied palladium(II) complexes, the [Pd(TSC3)2] (8) complex exhibited high antitumor activity on the DU145 prostate carcinoma and K562 chronic myelogenous leukemia cells, with low values of the inhibitory concentration (0.01 and 0.02 μM, resp.).

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The compounds [L1Cu(μ‐OH)2CuL1](ClO4)2 (1), [L2Cu(μ‐OH)2CuL2](ClO4)2 (2), [L3Cu(μ‐OH)2CuL3](ClO4)2 (3), [L3Cu(μ‐OMe)2CuL3](ClO4)2 (4), [L3Cu(μ‐F)2CuL3](BF4)2 (5), [L4Cu(μ‐Cl)2CuL4](ClO4)2 (6), and [Cu(μ‐L5)2Cu](ClO4)2 (7), where L1 = bis(pyridin‐2‐ylmethyl)benzylamine, L2 = (6‐methylpyridin‐2‐ylmethyl)(pyridin‐2‐ylmethyl)benzylamine, L3 = bis(6‐methylpyridin‐2‐ylmethyl)benzylamine, L4 = (pyridin‐2‐ylethyl)(pyridin‐2‐ylmethyl)benzylamine, and L5 =(6‐oxidomethylpyridin‐2‐ylmethyl)(6‐methylpyridin‐2‐ylmethyl)benzylamine, were structurally characterized and studied by low‐temperature EPR spectroscopy. The formation of compound 5 involved fluoride abstraction from BF4– and that of 7 involved O2‐assisted C–H (methyl) activation/monooxygenation of L3. Whereas the dications of 1–4 and 7 possess a square‐pyramidal configuration at the copper(II) centers with hydroxide or alkoxide bridges in equatorial positions, the dications of 5 and 6 exhibit equatorial/axial arrangements for the bridging halide ions. In the dication of 5, the tridentate ligand binds in a meridional fashion and includes two adjacent five‐membered chelate rings. Such a situation has been observed previously only with chloride, alkoxide, or aqua bridges. In contrast to the syn configuration of the dication of 2, the dications of complexes 1, 3, 4, and 7 adopt an anti configuration with respect to the binding of Ln. The dications of 1, 2, and 7 have the pyridinyl or 6‐methylpyridinyl groups in the axial position, whereas those of 3 and 4 feature the tertiary amine N atom at that site. DFT calculations of various configurations of the dications of 1–6 reproduce the experimentally observed structural alternatives in complexes 1–4, but they do not predict the axial/equatorial structure of 5 as the lowest‐energy configuration. The systematic overestimation of repulsive forces and thus of distances by DFT may result in an underestimation of the π‐π interaction between the largely coplanar mer‐L3 ligands separated by about 3.6 Å in 5, which probably affects its structure. By incorporating these and previous results, the syn versus anti, equatorial/equatorial versus equatorial/axial, and axial pyridine versus axial amine structural alternatives are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

A new series of dinuclear dysprosium­(III) complexes, [Dy2(LCH3 )2(NO3)2(MeOH)2] (I), [Dy2(LCH3 )2(NO3)2(DMF)2]·2DMF (II), [Dy2(LCl)2(NO3)2(DMF)2]·2DMF (III), and [Dy2(LCH3O)2(NO3)2(DMF)2] (IV), with 2,2′-[[(2-pyridinylmethyl)­imino]­di­(methylene)]­bis­(4-R-phenol), where R = CH3, Cl, and CH3O, were investigated as potential white light emitters. All octacoordinated dysprosium­(III) are phenoxo-bridged species and have a similar coordination environment. Nevertheless, I has a MeOH ligand molecule, while for II–IV a DMF ligand replaces that of MeOH. The nature of the coordinated solvent molecule plays an important role in the behavior of the thermal dependence of the Y/B (yellow/blue) emission ratio of the DyIII complexes (Y: 4F9/2 → 6H13/2, yellow and B: 4F9/2 → 6H15/2, blue transitions),, since for I the variation of this ratio is significant, while for the other DyIII complexes with DMF as ligand the ratio remains constant within experimental error. At room temperature the CIE (Commission International d’Eclairage) color coordinates for the DyIII complexes, I (0.286, 0.317), III (0.302, 0.324), and IV (0.322, 0.348) are close to the NTSC (National Television System(s) Committee) standard value for white color. Varying the temperature from 16 to 300 K the CIE coordinates for I change from the blueish to white region of the chromaticity diagram, while those of II present an inverse thermal dependence as compared to I. The CCT (Correlated Color Temperature) values at room temperature for I (8384 K), II (17235 K), and IV (5948 K) permit us to consider these complexes as candidates for white cold light emitters, the high value of II being uncommon. For I and II the CCT values vary strongly with temperature, showing a decrease with increasing temperature for I, and an increase with increasing temperature for II, thus making evident the influence on the photophysical properties of the nature of the coordinated solvent molecule in these complexes.

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The crystal structures of [CuJbdpdz) Br,]-2CH3CN 1, [Cu,(bdpdz)C13(H,0)]CI~3.5H,0 2 and [Cu,(bdpdz),] [CIO,], 3 were determined by X-ray analysis, where bdpdz represents the binucleating ligand 3,6-bis(di-2-pyridylmethyl) pyridazine, formed by the reaction of 3.6-dichloropyridazine and di-2pyridylmethyllithium. Compounds 1 and 2 consist of discrete binuclear units, in which copper atoms are linked by the diazine bridge and two halide ions. The pyridazine acts as a hexadentate ligand. In complex 2 the two copper(ii) ions have a distorted octahedral co-ordination geometry, 4 + 2. Compound 3 also consists of discrete binuclear units, in which the copper centres are linked by two organic ligands. Here bdpdz acts as a pentadentate ligand, with one of the diazine nitrogen atoms not bonded. The two copper(i1) ions have a square pyramidal co-ordination geometry, 4 + 1. The magnetic susceptibility was investigated in the temperature range 300-5 K. These measurements reveal an antiferromagnetic interaction for all three compounds (-W = 98.1 for 1, 79.6 for 2 and 6.4 cm-' for 3). The lack of a diazine bridge, N-N, for the perchlorate salt 3 substantially reduces the antiferromagnetic interaction. 61 9( 17) Results Structural Description of [Cu2(bdpdz)Br,]-2CH3CN 1 .-* Supplementary data available (No. SUP 56923,4 pp.): phase diagram.