Search results for "Denticity"
showing 10 items of 376 documents
Organotin(IV) Complexes of Aromatic Acid Hydrazides: Preparation and Spectroscopic Studies
1999
Abstract The ability of aromatic acid hydrazides, RCONHNH, to act as bidentate chelating agents towards diorganotin(IV) dichlorides has been investigated. The structure of the complexes were deduced from IR, NMR and Mossbauer spectroscopic techniques in combination with analytical data. The R2SnCI2.L complexes have octahedral geometry where the tin atom is chelated with one ligand (via carbonyl oxygen and hydrazinic nitrogen atoms), two chlorine atoms are in equatorial positions while the R groups are in the axial positions.
Adsorption mechanism of arsenate by zirconyl-functionalized activated carbon
2007
Arsenate [As(V)] and arsenite [As(III)] sorption at the solid-water interface of activated carbon impregnated with zirconyl nitrate (Zr-AC) was investigated using X-ray absorption spectroscopy (XAS) and surface complexation modeling. The XAS data at the Zr K-edge suggest that the structure of the zirconyl nitrate coating is built from chains of edge-sharing ZrO8 trigonal dodecahedra bound to each other through two double hydroxyl bridges. The 8-fold coordination of each Zr atom is completed by four O atoms, which share a bit less than the two theoretically possible bidentate nitrate groups. On impregnation, two of the O atoms may lose their nitrate group and be transformed to hydroxyl group…
Catalytic Efficiency of a New Tridentate Ferrocenyl Phosphine Auxiliary: Sonogashira Cross-Coupling Reactions of Alkynes with Aryl Bromides and Chlor…
2005
[structure: see text] The catalytic activity in Sonogashira cross-coupling reactions of alkynes with a variety of aryl halides (including chlorides) using a multidentate ferrocenyl phosphine is presented. The novel mixed ferrocenyl aryl/alkyl triphosphine is thermally stable and insensitive to air or moisture, and its robustness allows aryl alkynylation at 10(-1) to 10(-4) mol % catalyst loadings with TONs up to 250,000. Copper-free coupling using phenylacetylene is also accessible in good yield.
Organometallic Complexes with Biological Molecules, VI. Diorganotin(IV) and Triorganotin(IV) Ampicillin and Methicillin Derivatives: Spectroscopic In…
1996
Derivatives of D(-)-α-aminobenzylpenicillin (ampicillin) and of 2,6-dimethoxyphenylpenicillin (methicillin) with diorgano- and triorgano-tin(IV) moieties have been synthesized. The stoichiometries of the compounds obtained were of the type R 2 SnCIL.H 2 O, R 3 SnCILNa.H 2 O [L=ampicillin or methicillin monoanion; R=Me, Bu, Ph] and R 2 Snampic 2 . 2H 2 O (ampic=ampicillin; R=Me, Bu, Ph). For R 2 SnCIL.H 2 O and R 3 SnCILNa.-H 2 O, infrared (IR) data suggest five-coordination around the tin(IV) atom; in R 2 Snampic 2 .2H 2 O six-coordination is most likely to occur. Thermogravimetric (TG) analysis excludes any involvement in the coordination of tin(IV) by water molecules, in any of the compou…
Vanadium complexes with multidentate amine bisphenols
2014
The reaction of VO(acac)2 (acac(-) = acetyl acetonate) with tripodal glycine bisphenol H3L(1) under an ambient atmosphere yields a hexacoordinated vanadium(iv) complex [V(acac)(L(1))] (1). The corresponding reactions with tripodal 2-propanolamine bisphenol H3L(2) and potentially pentadentate ethoxyethanolamine bisphenol H3L(3) lead to the oxidation of the metal centre and formation of mononuclear oxovanadium(v) complexes [VO(L(2))] (2) and [VO(L(3))] (3), respectively. Alternatively, these latter two complexes can be prepared using VOSO4·5H2O or VO(OPr)3 as a precursor. The CV of 1 in an ACN solution shows a reversible one-electron process at E1/2 = +1.18 V, whereas 2 and 3 have an irrevers…
Cytotoxic Activity of Organotin(IV) Derivatives with Triazolopyrimidine Containing Exocyclic Oxygen Atoms
2020
In this study cytotoxicity of organotin(IV) compounds with 1,2,4-triazolo[1,5-a]pyrimidines, Me3Sn(5tpO) (1), n-Bu3Sn(5tpO) (2), Me3Sn(mtpO) (3), n-Bu3Sn(mtpO) (4), n-Bu3Sn(HtpO2) (5), Ph3Sn(HtpO2) (6) where 5HtpO = 4,5-dihydro-5-oxo-[1,2,4]triazolo-[1,5-a]pyrimidine, HmtpO = 4,7-dihydro-5-methyl-7-oxo-[1,2,4]triazolo-[1,5-a]pyrimidine, and H2tpO2 = 4,5,6,7-tetrahydro-5,7- dioxo-[1,2,4]triazolo-[1,5-a]-pyrimidine, was assessed on three different human tumor cell lines: HCT-116 (colorectal carcinoma), HepG2 (hepatocarcinoma) and MCF-7 (breast cancer). While 1 and 3 were inactive, compounds 2, 4, 5 and 6 inhibited the growth of the three tumor cell lines with IC50 values in the submicromolar …
Synthesis, structural, thermal, and magnetic investigations of Co(II), Ni(II), and Mn(II) pyrophosphate chains
2012
The reaction in water of cobalt(II), nickel(II) or manganese(II) chloride with 1,10-phenanthroline (phen) and sodium pyrophosphate (Na 4 P 2 O 7 ) at low pH (∼2) afforded three isostructural pyrophosphate complexes of an unprecedented one-dimensional typology, namely, {[M(phen)(H 2 O)(H 2 P 2 O 7 )]·H 2 O} n with M = Co( 1 ), Ni( 2 ) and Mn( 3 ). The di-hydrogen-pyrophosphate anion featured in these complexes adopts a rare bidentate/monodentate bridging mode leading to chain propagation. This unusual bridging pathway produces a metal–metal intra-chain separation of about 6.6–6.7 A for 1 – 3 , values much larger than the metal–metal distance across the classic bis-bidentate PPi in the parent…
New insights into the reactivity of the tantalocene hydride Cp′2TaH3 (Cp′=η5-tBuC5H4). Synthesis and characterisation of cationic Ta(V) complexes wit…
2002
Abstract Reaction of various neutral LXH bidentate ligands (2-aminobenzoic acid, acetylacetone, dibenzoylmethan and 2-aminobenzenethiol) with [Cp′2TaH2]+, obtained in situ from Cp′2TaH3 treated with triphenylmethan cation, affords after dihydrogen elimination the corresponding cationic species [Cp′2Ta(H)(LX)]+ in BF4 or PF6 salts. Complexes [Cp′2TaH(η2-O2CC6H4-o-NH2O,O′)]PF6 (3), {Cp′2Ta[η2-OC(Me)CHC(Me)OO,O′]}BF4 (4a), {Cp′2TaH[η2-OC(Ph)CHC(Ph)OO,O′]}BF4 (4b) and [Cp′2TaH(η2-SC6H4-o-NH2S,N)]PF6 (5) are characterised by analytical and spectroscopic methods. With thiopyridine, the kinetic (6) and the thermodynamic (6′) isomers [Cp′2TaH(η2-2-SC5H4NS,N)]PF6 are identified. Crystal struc…
Syntheses, crystal structures and magnetic properties of new oxalato-, croconato- and squarato-containing copper(ii) complexesElectronic supplementar…
2003
The preparation and magnetic investigation of five mononuclear copper(II) complexes of formula [Cu(pyim)(C2O4)(H2O)]·2H2O (1), [Cu(pyim)(C4O4)(H2O)2]·2H2O (2), Cu(pyim)(C5O5)·2.5H2O (3), [Cu(H2bim)(C2O4)(H2O)]·H2O (4) and [Cu(bpz)(C5O5)(H2O)] (5) [pyim=2-(2-pyridyl)imidazole, H2bim=2,2′-biimidazole, bpz=2,2′-bipyrazine, C2O42−=dianion of oxalic acid, C4O42−=dianion of squaric acid and C5O52−=dianion of croconic acid] are reported. The crystal structures of 1, 2, 4 and 5 have been determined. The copper atom has a distorted square pyramidal geometry in this family of complexes: two nitrogen atoms from the bidentate nitrogen donor [pyim (1 and 2), H2bim (4) and bpz (5)] and two oxygen atoms e…
Synthesis and crystal structure of the low-spin iron(II) complex [Fe(bpz)3](ClO4)2·H2O (bpz=2,2′-bipyrazine)
2004
Abstract The crystal structure of the title compound [Fe(bpz) 3 ](ClO 4 ) 2 · H 2 O (bpz=2,2 ′ -bipyrazine) has been determined by a single crystal X-ray diffraction study at 293(2) K. The complex is monoclinic, P 2 1 / c , a =17.263(3), b =9.983(2), c =17.921(4) A, β =107.94(3)°, V =2938.3(10) A 3 , Z =4, R =0.073 and R w =0.118. The structure is made up of tris-chelated [Fe(bpz) 3 ] 2+ cations, uncoordinated perchlorate anions and crystallization water molecules. The iron atom exhibits a FeN 6 distorted octahedral geometry with average Fe–N bond length and N–Fe–N bidentate angle of 1.962(5) A and 81.6(2)°. The value of the Fe–N bond distance and that of the room temperature magnetic mome…