Search

In order to test the possible presence of the intramolecular interactions O → M in the group 14 elements and its consequences on the geometry, the 2-methoxybenzyl chlorine was reacted with magnesium and subsequently with the group 14 chlorides, Ph3MCl, to produce the organometallic compounds (2-CH3OC6H4)CH2MPh3 [M = Si (1), Ge (2) and Pb (3)]. The compounds were fully characterized by elemental analysis, infrared spectroscopy, mass spectrometry (FAB+), and multinuclear (1H, 13C, 29Si, 207Pb) NMR spectroscopy. The compounds 1 and 2 also were investigated by single crystal X-ray diffraction analysis, they are isostructural with a triclinic crystal system and P-1 space group, exhibiting a distorted tetrahedral environment. The possible intramolecular O → M distances in 1 and 2 are 3.810 A and 3.802 A respectively, and represent more than the 100% of the sum of the appropriate Van der Waal’s radii. By comparison, in the previously reported tin analogous compound, that is not part of this work, the intramolecular distance O → Sn is ∼80% of the sum of the Van der Waal’s radii. The molecular structures of the four organometallic complexes were fully studied within the Density Functional Theory formalism.

The synthesis of five new complexes involving the ephedrinedithiocarbamate ligand (ephedtc) with group 13 and 15 metals (III) is reported. Complexes [As(ephedtc) 3 ] ( 1 ), [Sb(ephedtc) 3 ] ( 2 ), [Bi(ephedtc) 3 ] ( 3 ), and [In(ephedtc) 3 ] ( 5) were obtained from the ephedrinedithiocarbamate sodium salt [Na(ephedtc)] and the corresponding trichlorides MCl 3 , whereas for [Ga(ephedtc) 3 ], ( 4 ) Ga(NO 3 ) 3 was used. All compounds were characterized by elemental analyses, IR, mass spectrometry (FAB + ) and 1 H and 13 C NMR. In addition, single crystal structures of 2 and 5 were obtained showing two different coordination modes for the dithiocarbamate moiety, an anisobidentate coordination mode for 2 and an isobidentate coordination for 5 that generates a propeller-type structure. Compound 2 shows a distorted trigonal antiprismatic geometry around the metal atom while in 5 a distorted octahedral geometry is observed. Additionally, the crystalline structure of the ionic pair [ephedrinium] [ephedrinedithiocarbamate] ( 6 ) was determined. Antibacterial assay showed that 5 was the most active against ATCC bacterial strains and clinical isolate E. coli BLE (MIC 14.6–29.9 µM), and 3 against MRS strains (MIC 1.7 and 13.4 µM). The chemical hardness concept and the location of the HOMO and LUMO frontier orbitals on the molecular structures of 1 – 5 were employed to explain its particular antibacterial activity, using the DFT calculations.

Eighteen mononuclear diorganotin(IV) complexes derived from tridentate Schiff bases and R2SnO (IV) oxides (R = Me, n-Bu, Ph) were synthetized by multicomponent reactions in moderate yields. Complexes were characterized by common spectroscopic techniques such as FT-IR, UV–vis, mass spectrometry and NMR (1H, 13C and 119Sn) spectroscopy analysis. Nine complexes were characterized by single crystal X-ray diffraction analysis (1c, 1d, 1g, 1k, 1n, 1o, 1p, 1q and 1r). 119Sn NMR spectra showed signals at δ = 135–145, 175–185 and 319–323 ppm for Me, n-Bu and Ph derivatives respectively, indicating the pentacoordination of the tin atoms. In solid state, for compounds 1c, 1d, and 1g a distorted octahedral geometry for tin atoms was observed owing the presence of intermolecular Sn⋯O interactions, while for compounds 1k, 1n-1r, the pentacoordinate environment for tin atoms is observed. At supramolecular level the presence of O H⋯O, C H⋯O, C H⋯X (X = Cl, Br), C H⋯π and π⋯π interactions allow the formation of 1D and 2D polymeric chains.

The possibility of using less expensive and nontoxic metals, such as copper, as substitutes for more expensive heavy metals in the synthesis of new transition-metal complexes to be used as sensitizers in dye-sensitized solar cells (DSSCs) has stimulated research in this field. The novel photoluminescent copper(I) complex bis(triphenylphosphane-κP)[trans-(±)-2,4,5-tris(pyridin-2-yl)-2-imidazoline-κ2 N 2,N 3]copper(I) hexafluorophosphate, [CuI(C18H15N5)(C18H15P)2]PF6, has been successfully synthesized and characterized by IR and 1H NMR spectroscopy, as well as by single-crystal X-ray diffraction and thermogravimetric analysis. The complex showed interesting photophysical properties, which were studied experimentally in solution and in the solid state by UV–Vis and fluorescence spectroscopy. Density functional theory (DFT) calculations with dichloromethane as solvent reproduced reasonably well the HOMO and LUMO orbitals of the title compound.

The synthesis and characterization of six new O-cholesteryl-dithiophosphonates containing thio-metalloheterocycles of As(III) and Sb(III); (CH2S)2As[S2P(cholesteryl)(4-MeOC6H5)] (2), (CH2S)2Sb[S2P(cholesteryl)(4-MeOC6H5)] (3), O(CH2CH2S)2As[S2P(cholesteryl)(4-MeOC6H5)] (4), O(CH2CH2S)2Sb[S2P(cholesteryl)(4-MeOC6H5)] (5), S(CH2CH2S)2As [S2P(cholesteryl)(4-MeOC6H5)] (6), and S(CH2CH2S)2Sb[S2P(cholesteryl)(4-MeOC6H5)] (7) are reported. 2–7 have been prepared from the reaction between the triethylammonium salt of O-3β-cholest-5-en-3-yl (4-methoxyphenyl) dithiophosphonate (1) and five and eight membered chloro-metalloheterocycles of As(III) and Sb(III). The obtained compounds have been characterized by elemental analyses, IR and NMR (1H, 13C, and 31P) spectroscopy. The 31P NMR data suggest that the dithiophosphonate ligand presents, in solution, a bidentate coordination. The structures of 3 and 4 were determined by X-ray single crystal analysis, that correspond to the first examples of such determinations in Group 15 dithiophosphonates, showing an anisobidentate coordination mode of the dithiophosphonate moiety. Sb(III) and As(III) in compounds 3 and 4 present tetracoordination and pentacoordination, respectively. The pentacoordination in 4 is achieved through a 1,5 transannular As⋯O interaction. Antibacterial assays were performed and the activity was correlated with the electronic distribution and molecular shape, employing their geometrical structures, Mulliken partial charges, dipole moments and Molecular Electrostatic Potential maps from DFT calculations.

Sodium tetraphenylimidodiphosphinochalcogenide salts Na[(Ph2P(X)NP(X)Ph2)] (X = S, Se), react with 15-crown-5 ether to give two complexes [Na(15C5)][(Ph2P(X)NP(X)Ph2)] (X = S, Se), 1 and 2 respectively. The crystal and molecular structures of the resulting compounds were determined by X-ray diffractometry. The compounds are isostructural showing sodium–sulfur and sodium–selenium interactions, respectively, forming discrete inorganic (carbon free) chelate rings. These are different from the complex from the oxygen homolog which is an aggregated poly-ion, containing sodium ions with different coordination environments.

Four new stibocanes substituted with cyclic dithiophosphate ligands O(CH2CH2S)2SbS2P(OCH2)2CEt2 (1), O(CH2CH2S)2SbS2P(OCH2)2C(Me)Pr (2), S(CH2CH2S)2SbS2P(OCH2)2CEt2 (3) and S(CH2CH2S)2SbS2P(OCH2)2C(Me)Pr (4) were prepared from the corresponding chloro oxa- and thia-stibocanes and the sodium salt of the dithiophosphoric acids 5,5-diethyl-(2-mercapto-2-thiono-1,3,2-dioxaphosphinane) and 5-methyl-5-propyl-(2-mercapto-2-thiono-1,3,2-dioxaphosphinane) in ethanol. The compounds obtained were characterized by IR, EI-MS and multinuclear NMR (1H, 13C, 31P) spectroscopies. The single-crystal structures of 1 and 2 were determined which show the presence of three types of secondary bonding: i.e. strong Sb- - -O transannular interactions of 2.607(4) and 2.600(4) A, respectively, anisobidentate coordination of the ligand (exocyclic chelation) average Sb- - -S distance 3.355 A and intermolecular interactions that lead to supramolecular associations. The coordination geometry around antimony atom in both 1 and 2 can be described as Ψ tricapped trigonal bipyramidal AB4CD2E. The eight membered ring presents a boat-chair conformation in both compounds and the 1,3,2-dioxaphosphinane ring has the chair conformation, with the stibocane in the axial position.

Five new chlorodiorganotin(IV) complexes derived from dithiocarbamate ligands have been prepared and structurally characterized. The complexes 1–5 with the general formula {(Ph2SnCl)dtc} (dtc = R1R2NCS2−; 1, R1 = Bn, R2 = 9-anthrylmethyl; 2, R1 = Bn, R2 = 9-phenanthrylmethyl; 3, R1 = Bn, R2 = 1-pyrenylmethyl; 4, R1 = 1-naphthylmethyl, R2 = 1-pyrenylmethyl; 5, R1 = R2 = 1-pyrenylmethyl) have been obtained from Ph2SnCl2 and the sodium dithiocarbamate salts of benzyl(9-anthrylmethyl)amine, benzyl(9-phenanthrylmethyl)amine, benzyl(1-pyrenylmethyl)amine, 1-naphthylmethyl(1-pyrenylmethyl)amine and di(1-pyrenylmethyl)amine. Compounds 1–5 have been analyzed as far as possible by elemental analysis, FAB+ mass spectrometry, IR, UV–Vis, fluorescence and NMR (1H, 13C, 119Sn) spectroscopy, and single-crystal X-ray diffraction analysis (1–3). The solid-state and solution studies showed that the dtc ligands are coordinated to the tin atoms in the anisobidentate manner. In all cases the metal centers are five-coordinate. The coordination geometry is intermediate between square-pyramidal and trigonal-bipyramidal coordination polyhedra with τ-values in the range of 0.49–0.55. The crystal structures show the presence of C–H···Cl, C–H···S, C–H···π, offset π–π and S···π contacts. The stability of the (Ph2SnCl)dtc complexes in the presence of the acetate anion has been examined in acetonitrile solutions. For all of these organotin(IV) complexes the displacement of the coordinated ligands (i.e., chloride and dtc) by the acetate anion was observed. The lability, as well as their intrinsic fluorescent properties of the polyaromatic moieties in these (Ph2SnCl)dtc compounds make them interesting candidates to detect the presence of O-donor anions at very low concentrations by displacement of the metal-coordinated dtc.

Thirteen new stannacyclododecane dithiocarbamate complexes have been prepared by reacting 12-chloro-12-n-butyl-1,11-dioxa-4,8-dithia-12-stannacyclododecane (1) and 12-chloro-12-n-butyl-1,4,8,11-tetrathia-12-stannacyclododecane (2) with pyrrolidine-, morpholine-, thiomorpholine-, piperidine-, piperazinebis-, and 3-pyrroline-carbodithioates, respectively, as well as with diethyl-dithiocarbamate. All complexes were characterized by elemental analyses, IR, EI-MS, and NMR (1H, 13C, and 119Sn) studies. The spectroscopic data suggest the replacement of the chlorides by the corresponding dithiocarbamates with monodentate coordination, leading to six-coordinate tin atoms in all the cases.

One dinuclear chlorodiphenyltin (IV) dithiocarbamate complex (1) and four mononuclear complexes of general formula Ph2Sn(S2CNR)Cl (2, 3, 5, and 6) have been synthesized and characterized both in solidstate and solution. X-ray structures for complexes 1, 3 and 6 demonstrated a five-coordination geometry around of tin atoms, in which dithiocarbamate ligand chelates asymmetrically the metal center. As shown by 119 Sn NMR spectroscopy, five-coordination geometry observed in the solid-state remains in solution. The stability of these chlorodiphenyltin(IV) dithiocarbamate complexes in the presence of biologically relevant anions such as acetate, dicarboxylates of general formula � OOC-(CH2)n-COO � (n = 2–8), dihydrogenphosphate, hydrogensulfate, and halides has been examined in acetonitrile solutions. For all of these organotin(IV) complexes the displacement of the coordinated ligands (i.e., chloride and dithiocarbamate) from the organotin(IV) moiety occurred in the presence of monoanions like acetate, dihydrogenphosphate, hydrogensulfate and fluoride. A stepwise mechanism for ligand exchange is proposed based on UV–Vis, 1

An efficient synthesis of enantiomerically-pure β-aryl-γ-lactams is described. The principal feature of this synthesis is the practical resolution of β-aryl-γ-lactams with (S)-Naproxen. The procedure is based on the Michael addition of nitromethane to benzylidenemalonates, which was easily obtained, followed by the reduction of the γ-nitroester in the presence of Raney nickel and the subsequent saponification/decarboxylation reaction. The utility of this methodology was highlighted by the preparation of enantiomerically-pure (R)- and (S)-Baclofen hydrochloride.