Atif Fazal

Direct Access to Parent Amido Complexes of Rhodium and Iridium through NH Activation of Ammonia

Financial support from CONSOLIDER INGENIO-2010 program under the projects MULTICAT (CSD2009-00050) and Factoria de Cristalizacion (CSD2006-0015). P.G.O. acknowledges financial support from the CSIC “JAE-Doc” program.

Effective palladium(II)-bis(oxazoline) catalysts: synthesis, crystal structure, and catalytic coupling reactions

New bis(oxazoline) ligands and their palladium complexes were synthesized and characterized. X-ray crystal structures of the two new complexes showed distorted square planar geometry with the palladium ion bonded to nitrogens of two bidentate heterocycles in addition to two bromides and two acetate ions for Pd-BOX-1 and Pd-BOX-2, respectively. The complexes adopt a chair structure with a rigid curvature inducing an inherent chirality. The complexes were effective catalysts for Suzuki–Miyaura, Mizoroki–Heck, and copper-free Sonogashira coupling reactions in aqueous dimethylformamide and under aerobic conditions. The reaction conditions were optimized for best solvent, base, and temperature. The substrate scope of the new catalytic system was evaluated for coupling reactions of a variety of aryl halides with aryl boronic acids, alkenes, and alkynes.

Mercury(II) cyanide complexes of thioureas and the crystal structure of [(N-methylthiourea) 2 Hg(CN) 2 ]

Mercury(II) cyanide complexes of thioureas (Tu), N-methylthiourea (MeTu), and N,N′-dimethylthiourea (DmTu)) have been prepared and characterized by IR and NMR (1H and 13C) spectroscopy, and the crystal structure of one of them was determined by X-ray crystallography. An upfield shift in 13C NMR and downfield shifts in 1H NMR are consistent with the sulfur coordination to mercury(II). The appearance of a band around 2200 cm−1 in IR and a resonance around 145 ppm in 13C NMR indicates the binding of cyanide to mercury(II). The NMR data show that the [(Thione)2Hg(CN)2] complexes are stable in solution and undergo no redistribution reactions. In the crystal structure of the title complex, mercury atom is coordinated to two thione sulfur atoms of MeTu and to two cyanide carbon atoms in a distorted tetrahedral mode with the bond angles in the range of 90.2(2)°–169.3(3)°.

Dibromidobis(N,N,N',N'-tetra-methyl-thio-urea-κS)cadmium(II).

In the title compound, [CdBr2(C5H12N2S)2], the CdII atom lies on a twofold rotation axis. It exhibits a distorted tetrahedral coordination environment defined by two S atoms of two tetramethylthiourea (tmtu) ligands and two bromide ions. The crystal structure is consolidated by C—H⋯N and C—H⋯S hydrogen bonds.

Diiodidobis(N,N,N',N'-tetra-methyl-thio-urea-κS)cadmium(II).

In the title compound, [CdI2(C5H12N2S)2], the CdII ion is located on a twofold rotation axis and is coordinated in a distorted tetrahedral mode by two iodide ions and by two tetramethylthiourea (tmtu) ligands through their S atoms. The crystal structure is stabilized by C—H⋯N and C—H⋯S hydrogen bonds.

Structural characterization of tetrakis(1,3-diazinane-2-thione)cadmium(II) sulfate

A cadmium(II) complex tetrakis(1,3-diazinane-2-thione)cadmium(II) sulfate [Cd(Diaz)4]SO4 (1) is prepared and its crystal structure is determined by X-ray crystallography. The crystal structure of 1 consists of [Cd(Diaz)4]2+ and SO42− ions. In the complex ion, the central cadmium atom is coordinated by four Diaz molecules through sulfur atoms adopting a distorted tetrahedral geometry. The molecular structure is stabilized by N-H…O and N-H…S hydrogen bonding interactions. The complex is also characterized by IR and NMR spectroscopy and the spectroscopic data are discussed in terms of the nature of bonding.

Dichloridobis(N,N,N′,N′-tetra­methyl­thio­urea-κS)mercury(II)

In the title compound, [HgCl2(C5H12N2S)2], the HgII atom is located on a twofold rotation axis and is bonded in a distorted tetrahedral coordination mode to two chloride ions and to two tetramethylthiourea (tmtu) molecules through their S atoms. The crystal structure is stabilized by C—H⋯N and C—H⋯S hydrogen bonds.

Synthesis, crystal structures and catalytic activities of new palladium(II)–bis(oxazoline) complexes

Abstract Palladium–bis(oxazoline) complexes (Pd-BOX-A and Pd-BOX-B) were synthesized and characterized by 1H, 13C NMR, IR and elemental analysis. The molecular structures of the complexes were confirmed by single-crystal X-ray analysis. In both cases, the palladium center is coordinated by the nitrogen atoms of the two oxazoline rings and two chloride ligands in a distorted square planar geometry. Despite the fact that the bis(oxazoline) ligand is achiral, the asymmetrical substitution on the phenyl spacer and the rigid backbone of the complex Pd-BOX-A induce inherent chirality and the compound crystallizes as a racemic mixture. Both complexes were found to be highly effective catalysts for Suzuki–Miyaura, Mizoroki–Heck and Sonogashira cross-coupling reactions. They also show excellent catalytic activities toward carbonylative coupling reactions.

Bimetallic bis(diphenylphosphino)acetylene bridged copper(I) complexes with 1,10-phenanthroline derivatives: synthesis, crystal structure, and spectroscopic characterization

A new series of bimetallic bis(diphenylphosphino)acetylene-bridged copper(I) 1,10-phenanthroline complexes, [Cu2(dppa)2(L)2](BF4)2; L = 1,10-phenanthroline (1); 4-methyl-1,10-phenanthroline (2); 4,7-dimethyl-1,10-phenanthroline (3); and 2,9-dimethyl-1,10-phenanthroline (4), have been prepared and characterized by spectroscopic methods. The X-ray structures of 1 and 4 were determined. The structures consist of centrosymmetric bimetallic 10-membered chair-like dimetallacycles. In 1, intermolecular C–H⋯π interactions result in bending of the phenanthroline ligand and sterically induced lengthening of one Cu–P bond. In 1–4, the 31P NMR downfield coordination shift, relative to the free ligand, correlates with the basic strength of the 1,10-phenanthroline ligands. Graphical Abstract

A new water stable zinc metal organic framework as an electrode material for hydrazine sensing

Metal–organic frameworks (MOFs) are an emerging class of materials exhibiting high surface areas, controlled pore sizes, open metal sites and organic linkers. Utilizing MOFs as direct electrode materials for electrochemical sensing can offer inherent advantages such as containing a sensing element and a redox mediator in a single molecule; however, the direct use of MOFs as electrode materials is hindered because of their insulating nature and less stability in an aqueous medium. In this study, a new water stable Zn-MOF was synthesized and used directly as an electrode material. The Zn-MOF possesses good ability to electrocatalyze the hydrazine oxidation reaction. The Zn-MOFs inherent poor conductivity was overcome by including a hydrophobic electrolyte, tetrakis(4-chlorophenyl)borate tetradodecylammonium salt (ETH 500), during the fabrication of the Zn-MOF membrane. After coating a thin film of the nafion-ETH500 supported Zn-MOF over a glassy carbon electrode (GCE), the response for hydrazine oxidation was substantially improved. Linear sweep voltammetry (LSV) demonstrated a wide linear range from 20 to 350 μM (R2 = 0.9922) for hydrazine. A detection limit of 2 μM (n = 3) was observed. The electrochemical behavior of the ZnMOF/ETH500/nafion modified GCE revealed that MOFs have a promising future as electrode materials for direct electrochemical sensing.