Search results for "Adduct"
showing 10 items of 320 documents
Preparation of trichloro- and tribromocyclopentadienyltungsten(IV)
2000
International audience; The thermal decarbonylation of (Ring)WX3(CO)2 in refluxing toluene has led to the preparation of the CO-free compounds [(Ring)WX3]2 [Ring=η5-C5H5 (Cp) and X=Cl (1a) or Br (1b); Ring=η5-C5H4Me (Cp′), X=Cl (2a) or Br (2b); Ring=η5-C5Me5 (Cp*), X=Cl (3)]. The NMR properties of these molecules are consistent with diamagnetism and thereby indicate a different structure from that of the paramagnetic molybdenum analogues. Compounds 1a and 2a react with dppe to afford mononuclear 18-electron adducts, (Ring)WCl3(dppe) (Ring=Cp (4) or Cp′ (5)). The X-ray structure of 5 shows a pseudo-fac-octahedral geometry with the dppe ligand occupying two equatorial (e.g. cis relative to Cp…
Adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine II. Crystal and molecular structure of SnMe2Br2AZP and further mössbauer and p…
1990
Abstract A series of adducts of tin(IV) derivatives with 2,2′-azopyridine, AZP, has been studied by Mossbauer and X-ray photoelectronic spectroscopies and the crystal and molecular structure of SnMe2Br2- AZP has been determined. The linear correlation of the Mossbauer parameter isomer shift with partial atomic charge on tin suggests the occurrence of a single homologous series of isostructural adducts. The correlation of the Mossbauer parameter quadrupole splitting and C-Sn-C bond angle permits their calculation in SnMe2X2AZP adducts (X = Cl, Br). The N1s binding energies, obtained by XPS data, pointed out two slightly different values for both pyridinic and azo-group nitrogens. The crystal…
Straightforward Synthesis of Donor‐Stabilised Phosphenium Adducts from Imidazolium‐2‐carboxylate and Their Electronic Properties (Eur. J. Inorg. Chem…
2007
The cover picture shows one of donor-stabilized phosphenium compounds which have been obtained by direct addition of chlorophosphanes to the 1,3-dimethylimidazolium-2-carboxylate without any further purification step. Their stronger κ-acceptor character similar to phosphites and their ionic nature render these ligands very promising in the development of new continuous-flow catalytic processes. Details of phosphorylation mechanisms of imidazolium-2-carboxylate as well as the electronic and steric properties of these adducts are discussed in the article by J. Andrieu et al. on p. 4877 ff.
Zinc-salophen complexes as selective receptors for tertiary amines
2007
Zinc-salophen compounds 1-3 incorporating in the given order 1,2-diaminobenzene, 2,3-diaminonaphthalene, and 9,10-diaminophenantrene moieties were synthesised. Their binding properties toward a series of tertiary amines were assessed by UV-Vis and fluorescence spectroscopy in chloroform solution. Unprecedented selectivities of quinuclidine vs. triethylamine higher than 105 were recorded, thereby revealing the dramatic influence of steric effects on axial coordination of tertiary amines. X-Ray diffraction analyses showed that in the solid state compound 2 is dimeric, but its 1 : 1 quinuclidine complex is monomeric. Strong indications were obtained that both free receptors and their amine add…
Structure elucidation of the adducts formed by fjord region Dibenzo[a,l]pyrene-11,12-dihydrodiol 13,14-epoxides with deoxyguanosine.
1999
Model adducts to be used in the identification of biologically formed adducts were synthesized by reaction of fjord-region dibenzo[a,l]pyrene 11,12-dihydrodiol 13,14-epoxides (DB[a,l]PDE) and deoxyadenosine (dA). The (+/-)-anti-DB[a,l]PDE was reacted with dA in dimethylformamide at 100 degrees C for 30 min to give four DB[a, l]PDE-14-N(6)dA adducts: (-)-anti-trans (26%), (+)-anti-trans (26%), (-)-anti-cis (17%), and (+)-anti-cis (17%). The (+/-)-syn-DB[a,l]PDE was reacted with dA under the same conditions to yield four DB[a, l]PDE-14-N(6)dA adducts and one N7Ade adduct: (+)-syn-cis (19%), (+)-syn-trans (13%), (-)-syn-cis (19%), (-)-syn-trans (13%), and (+/-)-syn-DB[a,l]PDE-14-N7Ade (22%). T…
Synthesis of oligodeoxynucleotides containing diastereomeric dihydrodiol epoxide-N6-deoxyadenosine adducts of polycyclic aromatic hydrocarbons
1993
Abstract A generally applicable route is reported for the synthesis of oligodeoxynucleotides which contain structurally defined N 6 -deoxyadenosine adducts, derived from sterically highly hindered dihydrodiol epoxides of polycyclic aromatic hydrocarbons (PAH).
Synthesis, spectroscopic characterization and in vitro antimicrobial activity of diorganotin(IV) dichloride adducts with [1,2,4]triazolo-[1,5-a]pyrim…
2006
Abstract The heterocyclic ligands [1,2,4]triazolo-[1,5-a]pyrimidine (tp) and 5,7-dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidine (dmtp), react with diorganotin dichlorides giving the addition compounds Me2SnCl2(tp)2, Et2SnCl2(tp)2, Me2SnCl2(dmtp)2, Et2SnCl2(dmtp)2, Bu2SnCl2(dmtp), Ph2SnCl2(dmtp). The organotin:ligand stoichiometry goes from 1:2 to 1:1 by increasing the steric hindrance of the organic groups bound to tin. The compounds have been characterized by means of infrared, 119Sn Mossbauer and 1H AND 13C NMR spectroscopy. The ligands presumably coordinate to tin classically through the nitrogen atom at the position 3. The 1:1 complexes adopt trigonal bipyramidal structures, with the organi…
A Computational Study of Ethylene C−H Bond Activation by [Cp*Ir(PR3)]
2001
It has previously been demonstrated that both [(C5Me5)Ir(PMe3)(CH=CH2)H] and [(C5Me5)Ir(PMe3)(H2C=CH2)] are formed when [(C5Me5)Ir(PMe3)] is thermolytically generated in the presence of ethylene. At higher temperatures, the vinyl hydride is converted to the eta2-ethylene adduct. Density functional theory has now been used to investigate this reaction, using the B3LYP functional, two types of basis sets (LanL2DZ and TZV*), and two models of the [(C5R5)Ir(PR3)] species (R=H and CH3). The study consists of full optimizations of local minima, first-order saddle points, and minimum energy crossing points (MECP). The experimental results are best accounted for by considering both singlet and trip…
Synthesis and chemico-physical characterization of tin(IV) complexes with some crown ethers
1986
Abstract Some neutral adducts of diorganotin(IV) perchlorates and thiocyanates with three crown-ethers have been synthesised; they are of the type Me 2 SnX 2 L m · n H 2 O where m = 1 or 2, n = 2 or 4, X = ClO 4 or NCS, and L = 18-crown-6, 15-crown-5, and 12-crown-4. The values for m and n have been correlated with the coordinating ability of the two anions and with the steric hindrance by the crown ether molecules. From infrared and Mossbauer data, an octahedral coordination geometry is proposed for all the complexes. The Mossbauer parameters are discussed in terms of the electronegativity of the ligands on the tin(IV) center and of the distortions produced in the coordination polyhedra by…
ChemInform Abstract: Synthesis of Oligodeoxynucleotides Containing Diastereomeric Dihydrodiol Epoxide-N6-Deoxyadenosine Adducts of Polycyclic Aromati…
2010
Abstract A generally applicable route is reported for the synthesis of oligodeoxynucleotides which contain structurally defined N 6 -deoxyadenosine adducts, derived from sterically highly hindered dihydrodiol epoxides of polycyclic aromatic hydrocarbons (PAH).