Emilia García‐Martínez

Reaction of bromopentacarbonylrhenium(I) with ferrocenylcarbaldehyde thiosemicarbazones: the first X-ray diffraction studies of metal carbonyl complexes containing bidentate thiosemicarbazone ligands

Abstract The reactions of [ReBr(CO) 5 ] with ferrocenylcarbaldehyde thiosemicarbazones HL with different groups attached to the amide nitrogen (R=H, Me, Ph) yielded complexes [ReBr(CO) 3 (HL)] ( 1 ) in which, according to X-ray studies of 1a ·{(CH 3 ) 2 CO} and 1b ·1/2{CH 2 Cl 2 }, the thiosemicarbazone is N , S -bidentate and the geometry around the metal fac -octahedral. Compounds of formula [ReL(CO) 3 ] 2 ( 2 ) were then prepared by reaction of the corresponding adduct 1 with NaOMe in acetone. A complex of formula [ReL 2 (CO) 3 ] 2 ( 2b ′) was also obtained as a dissolvate by slow concentration of a solution of 1b in acetone. Single crystals of 2a and 2b obtained from the mother liquors are composed of centrosymmetric dimers formed by ReSRe bridges, where S is the thiolic sulfur of an N , S -bidentate thiosemicarbazonato ligand. Although 2b ·2{(CH 3 ) 2 CO} and 2b ′·2{(CH 3 ) 2 CO} have similar co-ordination spheres, they differ as regards the configuration of the thiosemicarbazonato ligand about the azomethine bond and certain bond lengths (notably ReN); it seems likely that the configuration of L 2− determines how close the rhenium can approach the N atom of the ligand, and hence the delocalization of the π electrons in the CNN fragment of the thiosemicarbazide chain. The mass, IR and UV–vis spectra of the complexes, and their electrochemical behavior, are also discussed.

Synthesis and structure–activity relationships of new arylpiperazines: para substitution with electron-withdrawing groups decrease binding to 5-HT1A and D2A receptors

Abstract Compounds in which N -phenylpiperazines were linked by a propyloxy chain to position 6 or 7 of a coumarin ring were designed and synthesised, and their affinities for 5-HT 1A and D 2A receptors were determined by radioligand binding assays. The influence of para substitution in the phenyl ring, substitution at position 4 of the coumarin system, and the coumarin position at which the piperazinylalkyl chain is linked was explored. Electron-withdrawing phenyl ring substituents para to the piperazine strongly reduced activity at both receptors. Binding at 5HT 1A was influenced by the bulk of substituents at position 4 of the coumarin system, and binding at D 2A by their electronic properties. Neither binding affinity was significantly affected by whether the piperazinylalkyl chain was inserted at position 6 or 7 of the coumarin system.

The Coordination Chemistry of the Versatile Ligand Bis(2‐pyridylthio)methane

Bis(2-pyridylthio)methane [bpytm, (pyS)2CH2] and complexes of this ligand with ZnII, HgII, CuI, and AgI have been prepared and characterised by elemental analysis, by IR, Raman and 1H and 13C NMR spectroscopy, and by X-ray diffractometry. The ligand is N, N′-didentate in the ZnII complexes; N-monodentate in one HgII complex and N, N′-bis(monodentate) in the other; N-mono-N′, S-didentate in the CuI complex; and N, S′-bis(mono)-N′, S-didentate in the AgI complex. The structural parameters of the ligand in each coordination mode are compared with those of the free ligand and those of the triiodide salt of the protonated ligand. Komplexchemie des vielseitigen Liganden Bis(2-pyridylthio)methan Bis(2-pyridylthio)methan, [bpytm, (pyS)2CH2], und Komplexe dieses Liganden mit ZnII, HgII, CuII und AgI wurden dargestellt und durch Elementarananalyse, IR-, Raman- sowie 1H- und 13C-NMR und Rontgenstrukturanalyse charakterisiert. Der Ligand ist N, N′-zweizahnig in den ZnII-Komplexen, N-einzahnig in einem und N, N′-bis(einzahnig) in den anderen HgII-Komplexen, N-mono-N′, S-zweizahnig im CuI-Komplex und N, S′-bis(mono)-N′, S-zweizahnig im AgI-Komplex. Die Strukturparameter des Liganden in jeder Koordinationsform werden mit denen des freien Liganden und denen des Triiodids des protonierten Liganden verglichen.

Bis(2-pyridylthio)methane complexes of cadmium(II) halides

Abstract The complexes [Cd2Cl4(bpytm)] (1), [CdBr2(bpytm)] (2), [Cd2Br4(bpytm)] (3) and [CdI2(bpytm)] (4) [bpytm=bis(2-pyridylthio)methane] were prepared and characterized by elemental chemical analysis, by IR, Raman and 1H and 13C NMR spectroscopy, and in the cases of 2 and 4 by X-ray diffractometry. In 2 and 4 the ligand is N,N′-bidentate, forming an eight-membered chelate ring.

Dimeric rhenium(I) thiosemicarbazone complexes: formation, crystal structures, and the role of N–H⋯π and C–H⋯O interactions

Dimeric complexes of composition [Re2X2(CO)6(HL)2] were obtained by reaction of fac-[ReX(CO)3(CH3CN)2] (X = Cl, Br) with 4-acetylpyridine thiosemicarbazone (HLH) and derivatives in which the thioamide nitrogen bore Me or Ph (HLMe and HLPh, respectively). In these complexes, which were characterized by X-ray crystallography and FAB, IR and 1H NMR spectroscopies, the thiosemicarbazone ligands bridge between two rhenium atoms by coordination of their Npyridine and S atoms. This coordination mode is unusual in that it does not involve any of the thiosemicarbazide nitrogen atoms. The isolation of dimeric complexes rather than monomers or polymers seems to have been due to their poor solubility and rapid precipitation from the reaction medium. [Re2Cl2(CO)6(HLH)2] (1a) was isolated in unsolvated form and as its acetone and acetonitrile solvates; [Re2Br2(CO)6(HLH)2] as its methanol solvate; and all the other complexes as acetone solvates. In all the solvated crystals except those of [Re2Cl2(CO)6(HLPh)2] (3a), all the solvent molecules are hydrogen-bonded to the complex, and in those of [Re2X2(CO)6(HLH)2] these hydrogen bonds contribute significantly to the cohesion of the structure (in particular, in [Re2Br2(CO)6(HLH)2]·2CH3OH there are no hydrogen bonds directly linking the dimers). In 3a·2(CH3)2CO the dimers are linked by N–H⋯π and C–H⋯O interactions, and the non-hydrogen-bonded solvent molecules occupy channels with interatomic long and short diameters of 8.5 and 5.6 A, respectively.

Supramolecular architectures of neutral and cationic complexes of transition metals with lactate and 1,10-phenanthroline

The following molecular complexes of transition metals MII with lactato (HL) and 1,10-phenanthroline (phen) ligands were prepared and characterized structurally: [M(HL)2(phen)]·nH2O, MII = Mn, Co, Ni, Cu, Zn; 1–6), [M(HL)(H2O)2(phen)]Cl, (MII = Mn, Co, Ni; 7–9), and [Ni(HL)(H2O)2(phen)]Br (10). These neutral and cationic octahedral complexes have 3-D supramolecular architectures due to weak noncovalent interactions. In the halide compounds, C–H⋯X− hydrogen bonds play a key role in the stabilization of the 3-D network.

The interaction of 2-methyllactic acid (H2mL) with divalent metal cations. The structures of (M(HmL)2(H2O)2), M /Mn(II), Zn(II)

Abstract The mononuclear complexes [M(HmL)2(H2O)2], where M=Mn(II) (1), Ni(II) (2) or Zn(II) (3) and HmL=2-methyllactato, were prepared and characterized by elemental analysis, FT-IR and UV/Vis spectroscopy and room temperature magnetic susceptibility measurements. Their thermal behaviour was also investigated, and compounds 1 and 3 were characterized by X-ray diffractometry. In both cases, the metal ion is hexacoordinated to two (O,O′)-bidentate monoanionic 2-methyllactato ligands and two aqua ligands in a distorted octahedral fashion. The [M(HmL)2(H2O)2] units are connected by hydrogen bonds, forming a two-dimensional network.

Metal coordination and in situ S–C bond cleavage of the bis(2-pyridylthio)methane ligand

The compound [2bpytmH](2)[I(3)](2)[I(2)], which contains protonated 2bpytm, and four neutral monomeric complexes [CoCl(2)(2bpytm)]·H(2)O (1), [CoBr(2)(2bpytm)] (2), [CoI(2)(2bpytm)]·1/2H(2)O (3) and [NiBr(2)(2bpytm)]·H(2)O (4) have been obtained during a study into the reactivity of the bis(2-pyridylthio)methane (2bpytm) ligand towards cobalt(II) and nickel(II) halides. Furthermore, a cyclic dimer [CuBr(2)(2bpytm)](2) (5) and a 1D polymer [CuBr(2)(2bpytm)](n)·CH(3)CN (6) have been obtained from copper(II)/(I) bromide salts. An unprecedented S-CH(2)-S activation and cleavage in 2bpytm has been observed on using copper(II) salts with organic and voluminous inorganic anions. The cleavage of 2bpytm enabled the isolation of copper(II) complexes containing the in situ generated ligands 2-pyridinethiolate, 2-pyridinesulfenate or 2-pyridinesulfonate.

Molecular metallocycles, acyclic metallodimers and 2D coordination polymers containing the twisted ligand bis(pyrimidin-2-ylthio)methane.

The versatile coordination chemistry of bis(pyrimidin-2-ylthio)methane (bptm) allows the synthesis of a series of different metal complexes with diverse structures. We describe here the synthesis and structural characterization of three kinds of compounds: four cyclic dimers, [Co(2)Cl(4)(bptm)(2)] (1), [Zn(2)I(4)(bptm)(2)] (2), [Cd(2)I(4)(bptm)(2)] (3), [Cu(2)(NO(3))(4)(bptm)(2)] (4); two acyclic dimers, [Cu(2)Br(4)(bptm)(3)] (5), [Cu(2)(AcO)(4)(bptm)(2)] (6); and two 2D coordination polymers, [CuBr(bptm)] (7) and [CuI(bptm)] (8). Different structural models are obtained on making small changes in the building units under different synthetic conditions. The effects of the weak interactions in the crystal packing were also analyzed.

Dichlorodiethylbis(pyridine-N)tin(IV)

In the title complex, [Sn(C2H5)2Cl2(C5H5N)2], the Sn atom lies on an inversion centre and is octahedrally coordinated by two Cl atoms, two ethyl C atoms and two pyridine N atoms in an all-trans configuration. The dihedral angle between the pyridine ring and the SnNCl plane is 22.4 (2)°.