Search results for "Denticity"
showing 10 items of 376 documents
Synthesis and spectroscopic characterization of R3SnIV derivatives ofN-acetyldipeptides
1993
Triorganotin(IV) derivatives of N-acetyldipeptides R3SnAcDip; RMe, Et, n-Bu, n-Oct, Cy or Ph (HAcDipN-acetylglycylglycine and N-acetylglycylvaline; RMe, n-Bu, Cy, HAcDipN-acetylglycylalanine) were obtained by neutralization of R3SnOH and HAcDip. The complexes were studied by means of 119Sn Mossbauer, IR and 1H, 13C and 119Sn NMR spectroscopy. The CSnC bond angles have been inferred by rationalization of Mossbauer nuclear quadrupole splittings as well as from NMR coupling constants. Correlations of Mossbauer isomer shifts with partial atomic charges on tin atoms have been determined: Polymeric trigonal bipyramidal structures, with near-planar R3Sn units and axial carboxylate (unidentate) and…
Ferromagnetic Coupling in “Double-Bridged” Dihydrogenpyrophosphate Complexes of Cobalt(II) and Nickel(II)
2015
Three isostructural compounds of the formula {[M(bipy)(H2O)(H2P2O7)]2·2H2O} [bipy = 2,2'-bipyridine; M = Ni (1), Co (2), Mn (3)] have been isolated from aqueous solutions containing the corresponding metal(II) chloride hydrate with a bipy and sodium pyrophosphate solution in a 1:1:2 molar ratio, and their structures were determined by single-crystal X-ray diffraction. The structures of 1-3 consist of neutral aqua(2,2'-bipyridine)metal(II) dinuclear units bridged by two dihydrogenpyrophosphate groups adopting a bidentate/monodentate mode. Each metal ion in 1-3 is six-coordinate in a distorted octahedral geometry, with the reduced value of the angle subtended by the chelating bipy at the meta…
Solution and solid state studies with the bis-oxalato building block [Cr(pyim)(C2O4)2]− [pyim = 2-(2′-pyridyl)imidazole]
2013
The preparation, X-ray structure, and variable temperature magnetic study of the new compound {Ba(H2O)3/2[Cr(pyim)(C2O4)2]2}n·9/2nH2O (1) [pyim = 2-(2′-pyridyl)imidazole and C2O42− = dianion of oxalic acid], together with the potentiometric and spectrophotometric studies of the protonation/deprotonation equilibria of the pyim ligand and the ternary complex [Cr(pyim)(C2O4)2]−, are reported herein. The crystal structure of 1 consists of neutral chains, with diamond-shaped units sharing barium(II), with the two other corners occupied by chromium(III). The two metal centers are connected through bis(bidentate) oxalate. Very weak antiferromagnetic interactions between the chromium(III) ions occu…
New Cu(II) and Zn(II) complexes of benzolamide with diethylenetriamine: synthesis, spectroscopy and X-ray structures
2000
Abstract New benzolamide (H2bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) zinc(II) and copper(II) complexes with diethylenetriamine were synthesized and characterized. The crystal structures of the [M(Hbz)2(dien)] (M=Cu(II), Zn(II); dien=diethylenetriamine) complexes were determined. The metal centre adopts a near regular square pyramidal geometry. The benzolamidate anion acts as a monodentate ligand through the thiadiazole N atom contiguous to the deprotonated sulfonamido group. Spectroscopic properties are in good agreement with the crystal structures. The EPR and electronic spectroscopic studies showed that the copper(II) species doped into the zinc(II) complex adopts a near s…
DFT analysis of titanium complexes with oxygen-containing bidentate ligands
2003
Strength of the TiO co-ordinate bond in several titanium complexes with bidentate ligands has been investigated by means of DFT. Mutual interaction of particular donors and their influence on Lewis acidity of the central atom have also been studied. The energy of ligand binding ranges from −19 to −454 kJ/mol, depending on the kind of donors. Calculations confirm that a strong donor, alkoxide anion, co-ordinatively saturates the titanium and makes binding of new ligands less exoenergetic. On the contrary, two oxygen atoms of similar donor number do not have much influence on each other. Strength of the TiO bonds in titanium complexes with certain oxygen-containing bidentate ligands has bee…
Synthesis and characterization of a Cu(II) complex of 2-benzylmercapto-5- methyl-1,3,4-thiadiazole (C10H10N2S 2)
2008
A Cu(II) complex of 2-benzylmercapto-5-methyl-1,3,4-thiadiazole was synthesized and characterized. The crystal structure of the copper complex and the free ligand were determined by single-crystal X-ray diffraction at room temperature: {[Cu(C10H10N2S2) 2(Cl)2], P1 triclinic, a = 8.1450(2) Å, b = 8.1690(2) Å, c = 10.8180(3) Å, α = 97.4040(12)°, β = 101.6270(11)°, γ = 116.1431(14)°; C10H10N2S2 ligand, Pbca orthorhombic, a = 8.7938(7) Å, b = 9.6491(7) Å, c = 25.3552(18) Å}. The metal complex framework consists of discrete units that provide crystalline stability through a network of van der Waals contacts. The Cu(II) is coordinated by two chloride ions and two 2-benzylmercapto-5-methyl-1,3,4- …
Nuclearity controlled cyanide-bridged bimetallic CrIII-MnII compounds: synthesis, crystal structures, magnetic properties and theoretical calculation…
2004
The preparation, X-ray crystallography and magnetic investigation of the compounds PPh4[Cr(bipy)(CN)4].2 CH3CN.H2O (1) (mononuclear), [[Cr(bipy)(CN)4]2Mn-(H2O)4].4H2O (2) (trinuclear), [[Cr(bipy)(CN)4]2Mn(H2O)2] (3) (chain) and [[Cr(bipy)(CN)4]2Mn(H2O)].H2O.CH3CN (4) (double chain) [bipy=2,2'-bipyridine; PPh4 (+)=tetraphenylphosphonium] are described herein. The [Cr(bipy)(CN)4]- unit act either as a monodentate (2) or bis-monodentate (3) ligand toward the manganese atom through one (2) or two (3) of its four cyanide groups. The manganese atom is six-coordinate with two (2) or four (3) cyanide nitrogens and four (2) or two (3) water molecules building a distorted octahedral environment. In 4…
Phenylmalonate‐Containing Copper( II ) Complexes: Synthesis, Crystal Structure and Magnetic Properties
2004
Three new copper(II) complexes of formula [Cu(2,2′-bpy)(Phmal)(H2O)]·2H2O (1), [{Cu(2,2′-bpym)(Phmal)}]n (2) and [{Cu(phen)(Phmal)}]n·3nH2O (3) (Phmal = phenylmalonate; 2,2′-bpy = 2,2′-bipyridine; 2,2′-bpym = 2,2′-bipyrimidine; phen = 1,10-phenanthroline) have been prepared and their structures determined by X-ray diffraction techniques. Complex 1 is mononuclear whereas 2 and 3 are uniform chain compounds. The copper atoms in 1−3 are distorted square-pyramidal: two nitrogen atoms from the bidentate nitrogen heterocycle and two carboxylate oxygen atoms from the phenylmalonate ligand build the equatorial plane; the axial position is filled either by a water molecule (1) or a carboxylate oxyge…
Different coordination modes of a 1,1′,2,2′-ferrocenyltetraphosphine: Bi- and tri-dentate behaviour with group 6 and 7 transition metals
2002
The behaviour of 1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-di(tert-butyl)ferrocene (1), acting as a homoannular or heteroannular ligand, has been studied. Due to the cisoid disposition of the phosphino groups of each ring, different coordination modes are observed. With group 6 metal carbonyls, M(CO)6, the tetraphosphine acts exclusively as a tridentate ligand. In contrast, the reaction with MnCp(CO)3 leads to complexes showing 1,1′ and 1,2 bidentate coordination modes. All these complexes have been characterised by 1H and 31P NMR spectroscopy. The molecular structures of the molybdenum complex [(1)Mo(CO)3] (2b) and the 1,1′ manganese complex [(1)MnCp(CO)] (3) have been established by X-ra…
Copper(II)-phenylmalonate complexes with the bifunctional ligands nicotinamide and isonicotinamide
2011
Abstract The use as coligands of the nicotinamide (nia) and isonicotinamide (inia) molecules in the complex formation between copper(II) and phenylmalonate [Phmal = dianion of phenylmalonic acid] yielded the compounds of formula [Cu(inia)(Phmal)(H2O)] (1) and [Cu(inia)(Phmal)(H2O)]n (2). Although single crystals of 1 of appropriate size were grown, their unresolved twinning and space group ambiguity prevented a satisfactory X-ray structure determination. The crystal structure 2 consists of corrugated layers of copper(II) ions with intralayer carboxylate–phenylmalonate bridges in the anti-syn (equatorial-apical) coordination mode. A water molecule and the isonicotinamide group are coordinate…