Search results for "helat"

( E )‐ und ( Z )‐Enole von β‐Ketocarbonsäureamiden

1990

(E)- and (Z)-Enols of β-Ketocarboxylic Acid Amides Reaction of dimesitoyldiazomethane (1) with ammonia (3a), primary and secondary amines (3b – o and 3p – v, respectively) leads to the completely enolized amides 4a – v. Besides the chelated Z configuration the unusual E isomer exists in the most cases, too. The Z/E distribution in the equilibrium depends on the steric and electronic effects present in the amide group CONR2R3 and on the solvent.

Cavitands incorporating a Lewis acid dinickel chelate function as receptors for halide anions.

2015

The halide binding properties of the cavitand [Ni2(L(Me2H4))](2+) (4) are reported. Cavitand 4 exhibits a chelating N3Ni(μ-S)2NiN3 moiety with two square-pyramidal Ni(II)N3S2 units situated in an anion binding pocket of ∼4 Å diameter formed by the organic backbone of the (L(Me2H4))(2-) macrocycle. The receptor reacts with fluoride, chloride (in MeCN/MeOH), and bromide (in MeCN) ions to afford an isostructural series of halogenido-bridged complexes [Ni2(L(Me2H4))(μ-Hal)](+) (Hal = F(-) (5), Cl(-) (6), and Br(-) (7)) featuring a N3Ni(μ-S)2(μ-Hal)NiN3 core structure. No reaction occurs with iodide or other polyatomic anions (ClO4(-), NO3(-), HCO3(-), H2PO4(-), HSO4(-), SO4(2-)). The binding ev…

Structural diversity within analogous compounds: syntheses and studies of M(SCH2CH2NH2)Cl (M = Zn, Cd, Hg).

2006

The novel complexes [Zn(L)Cl] (1), [Cd(L)Cl] (2), [Hg(L)Cl] (3), {[Hg(L)Cl]·NaOH·2H 2 O} (3·NaOH·2H 2 O), and {[Hg 3 (HL) 2 Cl 6 ]·2H 2 O} (4) (L = -SCH 2 CH 2 NH 2 ) were prepared and investigated by means of IR spectroscopy and single-crystal X-ray diffraction. The crystal structures of 1, 2, and 3·NaOH·2H 2 O show chelating N,S-coordination of the cysteaminate ligand, bridging S, and terminally coordinating Cl. Apart from these common features, the coordination geometries and modes of intermolecular association are different. 1 forms a cyclic tetramer with a Zn 4 S 4 ring, and 3·NaOH·2H 2 O contains one-dimensional [Hg(L)Cl] n chains with S-bridged Hg atoms. Zn and Hg atoms in 1 and 3·Na…

The tris(hexasulphido)platinate(IV) ion: Seven-membered chelate rings

1988

Le sel complexe [[(C 6 H 5 ) 4 P] 2 Pt(S 6 ) 3 ] a l'etat cristallin est prepare a partir de [N(C 2 H 5 ) 4 ] 2 PtS 17 ou (NH 4 ) 2 PtS 17 •H 2 O en solution dans l'acetone. Caracterisation structurale et configuration geometrique de l'anion Pt(S 6 ) 3 2−

Activation of C−H Bonds in Five-Membered Heterocycles by a Half-Sandwich Yttrium Alkyl Complex

2001

(Ni2), (Ni3), and (Ni2 + Ni3): A Unique Example of Isolated and Cocrystallized Ni2 and Ni3 Complexes

2009

Structural and magnetic characterization of compound {[Ni(2)(L)(2)(OAc)(2)][Ni(3)(L)(2)(OAc)(4)]}.2CH(3)CN (3) (HL = the tridentate Schiff base ligand, 2-[(3-methylamino-propylimino)-methyl]-phenol) shows that it is a rare example of a crystal incorporating a dinuclear Ni(II) compound, [Ni(2)(L)(2)(OAc)(2)], and a trinuclear one, [Ni(3)(L)(2)(OAc)(4)]. Even more unusual is the fact that both Ni(II) complexes, [Ni(2)(L)(2)(OAc)(2)] (1) and [Ni(3)(L)(2)(OAc)(4)(H(2)O)(2)].CH(2)Cl(2).2CH(3)OH (2), have also been isolated and structurally and magnetically characterized. The structural analysis reveals that the dimeric complexes [Ni(2)(L)(2)(OAc)(2)] in cocrystal 3 and in compound 1 are almost i…

Highly diastereoselective additions of organometallic reagents to 1-O-silylated 3,4-Di-O-benzyl-L-erythrulose derivatives

1993

Abstract The diastereoselectivity of the addition of several organometallic reagents to the carbonyl group of the title compounds has been investigated. Some organomagnesium reagents display high diastereoselectivities (90–99%) and the major products are those predicted by the α-chelation model.

Imidotungsten(VI) complexes with chelating amino and imino phenolates

2011

The reaction of WOCl(4) with 2,4-di-tert-butyl-6-((isopropylamino)methyl)phenol followed by the reaction with phenyl isocyanate leads to the formation of imidotungsten(VI) complex [W(NPh)Cl(3)(OC(6)H(3)(CH(2)NH-i-Pr)-2-t-Bu(2)-4,6)] 4 with a chelating aminophenolate ligand. When the same procedure was applied using aminophenols with bulkier substituents in the amino group, the final product was an unexpected Schiff-base complex [W(NPh)Cl(3)(OC(6)H(3)(CH=NPh)-2-t-Bu(2)-4,6)] 5, where the ligand is derived from 2,4-di-tert-butyl-6-((phenylimino)methyl)phenol. Complex 5 is also formed in the thermal degradation of 4. On the whole, 5 appears to be formed by a disproportionation of intermediate …

Synthesis and Complexation of the Metalloligand {(η5-C5H5)[η5-C5Me3-1,2-(PPh2)2]TiCl2} (TiPHOS): The First Example of a 1,2-Bis(diphenylphosphanyl)ti…

2001

The reaction of lithium 1,2-bis(diphenylphosphanyl)trimethylcyclopentadienide (1) with CpTiCl3 leads to the formation of the titanocene diphosphane {(η5-C5H5)[η5-C5Me3-1,2-(PPh2)2]TiCl2} (TiPHOS, 2). This metalloligand reacts readily with (NBD)Cr(CO)4 and W(CO)5(THF) to give, in both cases, the bimetallic chelate complexes (TiPHOS)Cr(CO)4 (3) and (TiPHOS)W(CO)4 (4). The structure of 4 has been determined by X-ray diffraction. The synthesis of a new early-late heterobimetallic complex (TiPHOS)Rh(CO)Cl (5) is reported.

Sequestering ability of some chelating agents towards methylmercury(II).

2013

A study on the interactions between CH3Hg+ and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H2 TLA)), 3-mercaptopropanoic acid (H2 MPA), 2-mercaptosuccinic acid (thiomalic acid (H3 TMA)), d,l-penicillamine (H2 PSH), l-cysteine (H2 CYS), glutathione (H3 GSH), N,N′-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H6 MLT)) and ethylenediaminetetraacetic acid (H4 EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For t…