Search results for "Denticity"
showing 10 items of 376 documents
Copper complexes modelling the interaction between benzolamide and Cu-substituted carbonic anhydrase. Crystal structure of Cu(bz)(NH3)4 complex
1998
New copper benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) complexes with ammonia, diethylentriamine (dien) and dipropylentriamine (dipn) have been prepared. The complex [Cu(bz)(NH 3 ) 4 ] crystallises in the monoclinic space group P 2 1 / n with a = 7.621(3), b = 19.91(5), c = 11.291(3) A, β = 93.17(4)° and Z = 4. The Cu(II) is five-coordinated with an almost regular square pyramidal geometry. The dideprotonated sulfonamide behaves as monodentate ligand interacting with the metal ion through the N atom of the unsubstituted sulfonamide group. In the EPR spectrum, exchange coupling between Cu(II) polyhedra of different orientations in the unit cell is observed. The …
Syntheses, crystal structures and magnetic properties of five new manganese(ii) complexes: Influence of the conformation of different alkyl/aryl subs…
2014
et al.
SEVERAL COORDINATION MODES OF 5-AMINO-1,3,4-THIADIAZOLE-2-SULFONAMIDE (HATS) WITH Cu(II), Ni(II) AND Zn(II): MIMETIC TERNARY COMPLEXES OF CARBONIC AN…
2001
Abstract The coordination properties of 5-amino-1,3,4-thiadiazole-2-sulfonamide (Hats) with Cu(II), Ni(II) and Zn(II) ions, are analyzed. Although the ligand presents several donor atoms, we have only observed three coordination behaviors: (i) as a monodentate ligand through the Nsulfonamido atom, (ii) as a bridging ligand linking the metal ions through the Nsulfonamido and Nthiadizole atoms and (iii) as a bridging ligand linking metal ions through the N and O atoms of the sulfonamidate group. It is noteworthy that coordination mode (iii) is observed for the first time in heterocyclic sulfonamides complexes. In addition, the conformation of the Hats as counter-ion is analyzed and compared w…
Functionalized Tri‐ and Tetraphosphine Ligands as a General Approach for Controlled Implantation of Phosphorus Donors with a High Local Density in Im…
2014
Supported phosphine ligands are auxiliaries of topical academic and industrial interest in catalysis promoted by transition metals. However, both controlled implantation and controlled conformation of ligands should be achieved to produce immobilized catalysts that are able to structurally “copy” efficient homogeneous systems. We provide herein a general synthetic strategy for assembling a new class of branched tetra- and triphosphine ligands with a unique controlled rigid conformation, and thus providing a high local density of phosphorus atoms for extended coordination to the metal center. We prepared new functionalized cyclopentadienyl (Cp) salts to design polyphosphines that were “ready…
Coordination chemistry of sulfamethizole: crystal structures of [Cu(sulfamethizolate)2(py)2(OH2)]·H2O, [M(sulfamethizolate)2(py)2(OH2)2] [M=Co and Ni…
2000
Abstract The synthesis and characterisation of copper, cobalt, nickel and zinc compounds with sulfamethizole (4-amino-N-(5-methyl-1,3,4-thiadiazole-2-yl)sulfanilamide) (Hsmtz) are described. The first crystal structures of ternary sulfamethizole complexes are reported. The crystal structures of Cu(smtz)2(py)2(OH2)·H2O (1), M(smtz)2(py)2(OH2)2 [M=Co (2), Ni (3)] and {Cu(smtz)2(dmf)2}∞ (5) were determined by X-ray diffraction. The Cu(II) ion exhibits a square pyramidal geometry in complex 1, while in the other compounds the metal ion presents a distorted octahedral environment. In compounds 1, 2 and 3 the deprotonated sulfamethizole acts as monodentate ligand coordinating through the thiadiaz…
Carbonylmolybdenum complexes with di(imino)pyridine and related ligands: Reduction of a di(imino)pyridine to an aminoiminopyridine system under mild …
2006
Abstract The reactions of [Mo(CO) 6 ] towards a 2,6-di(imino)pyridine L 1 and related ligands were studied. The reaction with L 1 afforded two new complexes, [Mo(CO) 4 L 1 ] ( 1 ) and [Mo(CO) 4 L 2 ] ( 2 ), where L 2 is the 2-amino-6-iminopyridine ligand arising from the hydrogenation of one imine function of L 1 ; similar reaction with a 2-acetyl-6-iminopyridine ligand L 3 afforded [Mo(CO) 4 L 3 ] ( 3 ). Compounds 1 , 2 and 3 have been fully characterised by IR, 1 H NMR and X-ray crystallography; they present a metal ion in a pseudo-octahedral environment, the three organic ligands acting with bidentate N 2 coordination modes. One of the imine functions in 1 , the amine function in 2 , and…
PCP-bridged chalcogen-centred anions: coordination chemistry and carbon-based reactivity.
2012
Since the discovery of the stabilising influence of thiophosphinoyl groups in methanediides by Le Floch et al. (Angew. Chem. Int. Ed., 2004, 43, 6382), numerous transition metal, lanthanide and actinide complexes of bis(thiophosphinoyl) carbene ligands have been investigated with an emphasis on the electronic structure and reactivity of the metal–carbon bonds. This Perspective begins by discussing main group (s- and p-block) complexes of this ligand and draws attention to differences compared to their d and f-block analogues. Investigations targeting the heavy chalcogen analogues of the Le Floch ligand have revealed an unusual carbon-based reactivity that led to the discovery of novel multi…
Synthesis and Structural Study of Tetravalent (Zr 4+ , Hf 4+ , Ce 4+ , Th 4+ , U 4+ ) Metal Complexes with Cyclic Hydroxamic Acids
2015
Six- and seven-membered cyclic hydroxamic acids, such as 1-hydroxypiperidine-2-one (1H, 1,2-PIPOH) and 1-hydroxyazepan-2-one (2H), have recently been identified in some mixed siderophores as one of their three chelating subunits. Compared to their ubiquitous noncyclic counterparts, cyclic hydroxamates are preorganized for metal binding. Surprisingly, the coordination chemistry of these bidentate, monoanionic ligands remains virtually unknown, even in the case of iron(III). We report herein the first structural study of the complexes of 1– and of 6–, an unsaturated seven-membered ring analog of 2–, with tetravalent cations of transition metals (zirconium and hafnium), lanthanide (cerium), an…
Synthesis, crystal structure and properties of two acetazolamide (5-acetamido-1,3,4-thiadiazole-2-sulfonamide) complexes: bis(5-acetamidato- 1,3,4-th…
1992
Abstract The diverse coordination chemistry exhibited by acetazolamide (H2acm), a potent inhibitor of the carbonic anhydrase metalloenzyme, is highlighted in two new copper(II) complexes of this ligand: [Cu(Hacm)2(en)2] (I) and [Cu(Hacm)2(tn)2] (II). The synthesis, crystal structure and spectroscopic properties of both compounds are reported in this paper. The structures of both compounds consist of discrete units of [Cu(Hacm)2(en)2] (I) and [Cu(Hacm)2(tn)2] (II), respectively, interacting through van der Waals contacts and hydrogen bonds only. Hacm, however, binds differently in each compound. In both cases, the Cu(II) ions, lying on the symmetry centers, show an elongated octahedral geome…
Synthesis of [5]Rotaxanes Containing Bi- and Tridentate Coordination Sites in the Axis
2010
A new example of a linear [5]rotaxane has been synthesized by using the traditional "gathering-and-threading" approach but based on an unusual axle incorporating a symmetrical bis(bidentate) chelating fragment built on a 4,7-phenanthroline core. The stoppering reaction is particularly noteworthy since, instead of using a trivial bulky stopper as precursor to the blocking group, two semistoppered copper-complexed [2]pseudorotaxanes (namely [2]semirotaxanes) are used, which leads to the desired [5]rotaxane in good yield. The efficiency of the method relies on the use of "click" chemistry, with its very mild conditions, and on the protection by a transition-metal (copper(I)) of the various coo…