Search results for "Denticity"
showing 10 items of 376 documents
Effects of preorganization in the chelation of UO22+ by hydroxamate ligands: cyclic PIPO– vs linear NMA–
2018
International audience; Many siderophores incorporate as bidentate chelating subunits linear and more seldomly cyclic hydroxamate groups. In this work, a comparative study of the uranyl binding properties in aqueous solution of two monohydroxamic acids, the prototypical linear N-methylacetohydroxamic acid (NMAH) and the cyclic analog 1-hydroxypiperidine-2-one (PIPOH), has been carried out. The complex [UO2(PIPO)(2)(H2O)] crystallized from slightly acidic water solutions (pH < 5), and its molecular structure was determined by X-ray diffraction. The uranyl speciation in the presence of both ligands has been thoroughly investigated in a 0.1 M KNO3 medium at 298.2 K by the combined use of four …
Topological control of the spin coupling in dinuclear copper(II) complexes with meta- and para-phenylenediamine bridging ligands
2010
Abstract A novel series of copper(II) complexes of formula [Cu(tren)(mpda)](ClO4)2 · 1/2H2O (1), [Cu2(tren)2(mpda)](ClO4)4 · 2H2O (2), and [Cu2(tren)2(ppda)](ClO4)4 · 2H2O (3) containing the tetradentate tris(2-aminoethyl)amine (tren) terminal ligand and the potentially bridging 1,n-phenylenediamine [n = 3 (mpda) and 4 (ppda)] ligand have been prepared and spectroscopically characterized. X-ray diffraction on single crystals of 1 and 3 show the presence of mono- (1) and dinuclear (3) copper(II) units where the mpda (1) and ppda (3) ligands adopt terminal monodentate (1) and bridging bis(monodentate) (3) coordination modes toward [Cu(tren)]2+ cations with an overall non-planar, orthogonal di…
Synthesis, Crystal Structures, and Magnetic Properties of a New Family of Heterometallic Cyanide-Bridged FeIII2MII2 (M = Mn, Ni, and Co) Square Compl…
2011
New heterobimetallic tetranuclear complexes of formula [Fe(III){B(pz)(4)}(CN)(2)(μ-CN)Mn(II)(bpy)(2)](2)(ClO(4))(2)·CH(3)CN (1), [Fe(III){HB(pz)(3)}(CN)(2)(μ-CN)Ni(II)(dmphen)(2)](2)(ClO(4))(2)·2CH(3)OH (2a), [Fe(III){B(pz)(4)}(CN)(2)(μ-CN)Ni(II)(dmphen)(2)](2)(ClO(4))(2)·2CH(3)OH (2b), [Fe(III){HB(pz)(3)}(CN)(2)(μ-CN)Co(II)(dmphen)(2)](2)(ClO(4))(2)·2CH(3)OH (3a), and [Fe(III){B(pz)(4)}(CN)(2)(μ-CN)Co(II)(dmphen)(2)](2)(ClO(4))(2)·2CH(3)OH (3b), [HB(pz)(3)(-) = hydrotris(1-pyrazolyl)borate, B(Pz)(4)(-) = tetrakis(1-pyrazolyl)borate, dmphen = 2,9-dimethyl-1,10-phenanthroline, bpy = 2,2'-bipyridine] have been synthesized and structurally and magnetically characterized. Complexes 1-3b have be…
Mono-organotin(IV) and tin(IV) derivatives of 2-mercaptopyridine and 2-mercaptopyrimidine: X-ray structures of methyl-tris(2-pyridinethiolato)tin(IV)…
1997
Mono-organotin(IV) and tin(IV) derivatives of 2-mercaptopyridine (HSPy) and 2-mercaptopyrimidine (HSPym), RSnL 3 (R=Me, n-Bu, Ph; L=SPy, SPym; R=Bz=benzyl, o-CIBz, oClC 6 H 4 , p-ClC 6 H 4 , o-tolyl, p-tolyl; L=SPy), RSnCIL 2 (R=Me, n-Bu, Ph; L=SPy, SPym), RSnCI 2 L (R=Me, n-Bu; L=SPy, SPym) and SnCI 4-n L n (L=SPy, SPym; n=2,4) were obtained from RSnCI 3 or SnCI 4 and NaL or by neutralization (R=Ph,p-tolyl; L=SPy, SPym). RSnCIL 2 and RSnCI 2 L were better prepared by comproportionation of RSnCI 3 and RSnL 3 . MeSn(Spy) 3 and PhSn(SPy) 3 .1.5CHCI 3 crystals, as determined by single-crystal X-ray diffraction, are monoclinic. In the discrete monomeric RSn(SPy) 3 units, three bidentate SPy lig…
DNA binding, nuclease activity, DNA photocleavage and cytotoxic properties of Cu(II) complexes of N-substituted sulfonamides.
2013
Abstract Ternary copper(II) complexes [Cu(NST)2(phen)] (1) and [Cu(NST)2(NH3)2]·H2O (2) [HNST = N-(4,5-dimethylthiazol-2-yl)naphthalene-1-sulfonamide] were prepared and characterized by physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square planar CuN4 geometry in which the deprotonated sulfonamide, acting as monodentate ligand, binds to the metal ion through the thiazole N atom. Both complexes present intermolecular π–π stacking interactions between phenanthroline rings (compound 1) and between naphthalene rings (compound 2). The interaction of the complexes with CT DNA was studied b…
Ni(II) and Zn(II) complexes with cinoxacin. Synthesis and characterization of M(Cx)2(DMSO)n(H2O)m (n=0, 2; m=2, 4). Crystal structures of [M(Cx)2(DMS…
1993
Abstract New metal complexes of cinoxacin (HCx=1-ethyl-l,4-dihydro-4-oxo(1,3)dioxolo(4,5-g)cinnoline-3-carboxylic acid) were synthesized, isolated as [Zn(Cx)2(DMSO)2]·4H2O, [Ni(Cx)2(DMSO)2]·4H2O, Zn(Cx)2·4H20 and Ni(Cx)2·2H2O, and characterized by elemental analysis, TG studies, IR and UVVis spectroscopic techniques. The crystal and molecular structures of the complexes [M(Cx)2(DMSO)2]·4H2O (M=Zn(II), Ni(II)) have been determined by X-ray structure analysis. The crystals of [Zn(Cx)2(DMSO)2]·4H2O are triclinic, space group P 1 with unit cell dimensions a=8.950(4), b=9.168(5), c=11.650(6) A, α=69.06(1), β=82.05(1), γ=75.63(1)°, V=863.6(8) A3; [Ni(Cx)2(DMSO)2]·4H20 is monoclinic, space group …
Structural properties and applications of multidentate [O,N,O,X'] aminobisphenolate metal complexies
2012
Abstract Aminobisphenols with side-arm donors are versatile tetradentate ligands that effectively coordinate to the metal ions in a tripodal fashion. Most of the metal ions form electrically neutral isolable complexes with aminobisphenolates with different side chains. However, some anionic complexes and zwitterions are also described. The coordination geometry of the metal centre can be controlled by the ligand design. Especially, the ortho -substituents of the phenolate moieties as well as the nature of side-arm donor influence the structure and reactivity of the complexes formed. Depending on the metal ion and the ligand environment, the complexes formed can be monomeric or dimeric ones.…
Bis‐μ‐pyrazolate‐Bridged Dinickel(II) and Dicopper(II) Complexes: An Example of Stereoelectronic Preference of Metal Ions and Stabilization of Mixed‐…
2007
New dimeric nickel(II) and copper(II) complexes [(L)Ni(μ-L′)]2[ClO4]21 and [(L)Cu(μ-L′)]2[ClO4]22, [2-[3-(2′-pyridyl)pyrazol-1-ylmethyl]pyridine (L) and 3-(2-pyridyl)pyrazole (HL′)] have been synthesized, structurally characterized, and their absorption, magnetic, EPR and redox properties investigated. The crystal structure of 1·MeCN reveals a planar {Ni2(μ-L′)2}2+ core [Ni···Ni separation: 4.0765(10) A] in which each distorted octahedral NiII ions is terminally coordinated by a tridentate ligand L and bridged by two HL′ units, in their deprotonated form. The structural analysis of 2·2MeCN reveals two five-coordinate CuII ions, each terminally coordinated by adopting only a bidentate coordi…
Trimethylplatinum(IV) complexes with ON bidentate ligands
1972
Abstract Complexes of the trimethylplatinum(IV) moiety with bidentate monobasic salicylaldimines C 6 H 5 (OH)CHNR (R = ethyl, propyl, phenyl) have been prepared and characterized by IR, UV and NMR spectra and magnetic susceptibility measurements. The complexes are dimeric with double PtOPt bridges, and the metal appears to be pseudo-octahedrally hexacoordinated.
Organozin- und organobleiderivate von N-(2,4-dinitrophenyl)glycin
1982
Abstract Organotin and organolead derivatives of N -(2,4-dinitrophenyl)glycine (HDNG), R 3 MDNG (M = Sn, Pb; R = CH 3 , C 6 H 5 ) and (C 6 H 5 ) 2 Pb(DNG) 2 , have been prepared from R 3 MOH or [(C 6 H 5 ) 2 PbO] n and HDNG, respectively. (CH 3 ) 3 PbDNG was also obtained from (CH 3 ) 3 PbBr and TlDNG. According to spectroscopic data R 3 M groups in R 3 MDNG are essentially planar and are bridged by bidentate carboxylate groups of DNG. NH does not coordinate to M. Penta-coordination is also indicated by Mossbauer data of R 3 SnDNG. Also for (C 6 H 5 ) 2 Pb(DNG) 2 a chain structure but with hexacoordination of Pb is proposed. The compounds are monomeric in solution.