Showing papers by "Jan Reedijk published in 1984"

Synthesis, structure, and spectroscopic properties of copper(II) compounds containing nitrogen–sulphur donor ligands; the crystal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane]copper(II) perchlorate

Abstract: The linear quadridentate N2S2 donor ligand 1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane (bmdhp) forms mono- and di-hydrate 1 : 1 copper(II) complexes which are significantly more stable toward autoreduction than those of the non-methylated analogue. The deep green monohydrate of the perchlorate salt crystallises as the mononuclear aqua-complex, [Cu(bmdhp)(OH2)][ClO4]2, in the monoclinic space group P21/n, with Z= 4, a= 18.459(3), b= 10.362(2), c= 16.365(3)A, and β= 117.14(1)°. The structure was solved and refined by standard Patterson, Fourier, and least-squares techniques to R= 0.047 and R′= 0.075 for 3 343 independent reflections with l > 2σ(l). The compound consists of [Cu(bmdhp)(OH2)]2+ ions and ClO4– counter ions. The co-ordination around copper is intermediate between trigonal bipyramidal and square pyramidal, with Cu–N distances of 1.950(4) and 1.997(4)A, Cu–O(water) 2.225(4)A, and Cu–S 2.328(1) and 2.337(1)A. In the solid state, the perchlorate dihydrate's co-ordination sphere may be a topoisomer of the monohydrate's. A new angular structural parameter, τ, is defined and proposed as an index of trigonality, as a general descriptor of five-co-ordinate centric molecules. By this criterion, the irregular co-ordination geometry of [Cu(bmdhp)(OH2)]2+ in the solid state is described as being 48% along the pathway of distortion from square pyramidal toward trigonal bipyramidal. In the electronic spectrum of the complex, assignment is made of the S(thioether)→ Cu charge-transfer bands by comparison with those of the colourless complex Zn(bmdhp)(OH)(ClO4). E.s.r. and ligand-field spectra show that the copper(II) compounds adopt a tetragonal structure in donor solvents.

Synthesis, spectroscopic characterization, and magnetic properties of unusual 3,5-dialkyl-1,2,4-triazole compounds containing N-bridging isothiocyanato ligands. X-ray structure of trinuclear bis[(.mu.-thiocyanato-N)bis(.mu.-3,5-diethyl-1,2,4-triazole-N1,N2)bis(thiocyanato-N)(3,5-diethyl-1,2,4-triazole-N1)nickel(II)-N,N1,N1']nickel(II) dihydrate

Abstract: Le complexe du titre cristallise dans le systeme Pbca avec a=14,447, b=23,047 et c=18,613 A, Z=4. Affinement jusqu'a R=0,058. Coordination octaedrique des trois atomes Ni. Les interactions d'echange magnetique entre les ions metalliques sont faibles mais importantes

Crystal structure at 300 and 105 k, magnetic properties and moessbauer spectra of bis(triaquatris(4‐ethyltriazole‐n1)iron(ii)‐n2,n2′,n2“)iron(ii) hexakis(trifluoromethanesulfonate). a linear, trinuclear iron(ii) compound, showing a unique high‐spin‐low‐spin transition of the central iron atom

Abstract: Etude RX c cristallisation dans P31c avec Z=2; affinement jusqu'a R=0,041 (a 300 K) et R=0,064 (a 105 K). Susceptibilite magnetique a basse temperature et donnees Mossbauer

Reaction products of cis-diammineplatinum(II) compounds with 5'-guanosine monophosphate characterized by high-frequency proton NMR

Abstract: En presence d'un exces d'ions Cl − , cis-PtCl 2 (NH 3 ) 2 reagit lentement avec GMP-5' meme a temperature elevee. Le produit initial est [cis-Pt(NH 3 ) 2 (GMP)Cl] et les produits secondaires [cis-Pt(NH 3 ) 2 (GMP) 2 ] et [cis-Pt(NH 3 ) 2 (GMP)(H 2 O)] + . Etude RMN de 1 H

Distortion isomerism in a thiocyanate-bridged copper(II) dimer. X-ray structure of .beta.-bis(.mu.-thiocyanato-N,S)-bis[bis(5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine)(thiocyanato-N)copper(II)] and comparison of its spectral and structural properties with those of other copper(II) 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine thiocyanates

Abstract: Le thiocyanate de Cu(II) et la dimethyl-5,7 triazolo-1,2,4 [1,5-a] pyrimidine (C 7 H 8 N 4 , dmtp) forment trois complexes differents: deux isomeres de composition [Cu(NCS) 2 (dmtp) 2 ] 2 et l'espece hydratee Cu(NCS) 2 (dmtp) 2 H 2 O. Etude RX de l'isomere β de [Cu(NCS) 2 (dmtp) 2 ] 2 : cristallisation dans P2 1 /n avec Z=4; affinement jusqu'a R=0,034. Ce compose est un dimere autosymetrique

Synthesis, structure, and magnetic properties of fluoride-bridged copper(II) dimers. Crystal and molecular structures of bis(.mu.-fluoro)bis[tris(3,4,5-trimethylpyrazole-N2)copper(II)] bis(tetrafluoroborate) and bis(.mu.-fluoro)bis[(5-methylpyrazole-N2)bis(3,5-dimethylpyrazole-N2)copper(II)] bis(tetrafluoroborate)

Abstract: (I) cristallise dans P2 1 /n avec Z=2; affinement jusqu'a R=0,033. (II) cristallise dans P2 1 /c avec Z=2; affinement jusqu'a R=0,035. Geometrie approximativement pyramide a base carree dans les deux cas. Comparaison a des dimeres complexes de Cu(II) apparentes. Mesures de susceptibilite magnetique jusqu'a 2K. Spectres RPE

Synthesis and co-ordination chemistry of a novel dinucleating chelating triazole ligand. The crystal structure of bis-µ-[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-N′, µ-N1,µ-N2,N″,]-bis[aquachloro-nickel(II)] dichloride tetrahydrate

Abstract: Reaction of 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt) with nickel(II) and cobalt (II) salts produces dinuclear co-ordination compounds. One of the compounds, [Ni2(abpt)2Cl2(H2O)2]Cl2·4H2O, crystallizes in the triclinic space group P with a= 6.840(2), b= 10.199(4), c= 12.480(3)A, α= 78.62(3), β= 76.47(2), γ= 84.17(3)°, and Z= 1. Refinement based on 4 015 independent reflections yielded a value for R′ of 0.034. The dinuclear Ni2(abpt)2 unit is almost planar. The nickel ions are co-ordinated by four nitrogen atoms with N–Ni–N angles of 93.00(4), 76.74(4), 113.67(4), and 76.47(4)° and Ni–N distances of 2.013(1), 2.029(1), 2.155(1), and 2.164(1)A. The axial ligands are a water molecule and a chloride ion. The co-ordination of the metal centres is rhombically distorted octahedral. The uncommon ligand-field spectrum is interpreted along with these findings. Variable-temperature magnetic susceptibility measurements for analogous compounds of NiII and CoII with BF4–, Cl–, or Br– anions revealed that a relatively weak antiferromagnetic exchange is present in these compounds.

Synthesis, structure, and spectral characterization of nickel(II) (R,R)-tartrate. Crystal and molecular structure of polymeric diaquabis((R,R)-tartrato-O1,O2:O3,O4)dinickel(II) trihydrate at -162.degree.C

Abstract: Cristallisation dans le groupe d'espace P2 1 2 1 2 1 (Z=2; affinement jusqu'a R=0,026). Chaque dianion tartrato est lie aux 2Ni d'une unite dimerique par 2O des groupements carboxyliques et 2O des groupements hydroxyles. Les deux autres O sont lies a une autre entite dimerique

Synthesis, spectroscopic properties, and X-ray structure of [1,7-bis(5-methylimidazol-4-yl)-2,6-dithiaheptane]dichlorocopper(II): a compound with unusually long copper(II)-thioether bonds

Abstract: Cristallisation dans le groupe Pbca. Affinement jusqu'a R=0,022. L'environnement de Cu(II) est un octaedre comprime, avec les 2N du cycle imidazole le long de l'axe principal; 2Cl et 2S etant situes dans le plan equatorial Cu−S=2,886 et 2,970 A. Discussion des spectres RPE et electronique

Transition-metal co-ordination compounds containing a novel tridentate pyrazole chelating ligand. X-Ray crystal structure of [NN-bis(3,5-dimethylpyrazol-1-ylmethyl)aminoethane](nitrato-O)-(nitrato-O,O′)nickel (II)

Abstract: The synthesis and characterization of transition-metal co-ordination compounds containing the newly synthesized ligand NN-bis(3,5-dimethylpyrazol-1-ylmethyl)aminoethane (bdmpae) are described. The compounds have the general formulae [M(bdmpae)X2](M = Co, Ni, Cu, or Zn; X = Cl, Br, or NO3) and [M(bdmpae)2][ClO4]2(M = Co or Ni). The compounds have been characterized by spectroscopic measurements and conductivity studies in solution. In most compounds the ligand behaves as a chelating tridentate ligand. In the mono-adducts the co-ordination around the metal ions is completed by two anions, resulting in a five-co-ordinate geometry (X = Cl or Br) or a six-co-ordinate geometry (X = NO3; in this case one nitrate is monodentate and the other is bidentate). The bis-adducts appear to have distorted octahedral co-ordination geometries for the metal ions. To prove the chelating nature of the ligand, and in particular the co-ordination of the amine nitrogen, the X-ray structure of one representative example was undertaken. Crystals of [Ni(bdmpae)(NO3)2] are of space group P21/c, with a= 8.511(3), b= 14.103(3), c= 15.865(8)A, β= 92.75(3)°, and Z= 4. Standard least-squares refinements resulted in R= 0.041 (R′= 0.059). The nickel atom has a NiN3O3(mer) chromophore in a distorted octahedral geometry. One nitrate group is monodentate [Ni–O 2.052(5)A], whereas the other is bidentate [Ni–O 2.157(5) and 2.145(5)A]. Ni–N distances are 2.061 (5) and 2.034(5)A for the pyrazole nitrogens and 2.128(5)A for the amine nitrogen.

Mossbauer relaxation study of nonlinear excitations in pure and impure Ising-type ferromagnetic quantum chains

Abstract: Nonlinear domain-wall dynamics in the quasi-one-dimensional ferromagnet ${\mathrm{FeCl}}_{2}$ ${(\mathrm{pyridine})}_{2}$ is studied by M\"ossbauer and susceptibility experiments. In particular, the influence of doping with nonmagnetic impurities is considered. In the interpretation of the experiments the predictions for classical sine-Gordon solitons are compared with those for quantum-mechanical magnon bound states in the $S=\frac{1}{2}$ discrete Ising-type ferromagnetic chain.

Tetrakis(imidazole)copper(II) fluorides. The crystal and molecular structure of diaquatetrakis(imidazole)copper(II) difluoride

Abstract: Two new fluoride-containing co-ordination compounds [Cu(Him)4(H2O)2]F2 and [Cu(Him)4][BF4]F (Him = imidazole) are described. From i.r. spectra, ligand-field spectra, and e.s.r. spectra it is concluded that the fluoride ions in both compounds are not co-ordinated to the metal ion. The crystal structure determination of [Cu(Him)4(H2O)2]F2 confirmed these conclusions. The compound crystallizes in space group C2/c, with cell dimensions a= 12.708(3), b= 10.299(2), c= 13.915(3)A; β= 106.63(2)°, and Z= 4. The structure was solved using direct phasing and difference-Fourier techniques and refined by full-matrix least-squares methods. The final discrepancy factor, R= 0.027, was based on 1 468 reflections. The copper ions are co-ordinated by four imidazoles and two water molecules. The F– ions are not co-ordinated to copper. They are strongly hydrogen bonded in a distorted tetrahedron of two imidazole H atoms and two H atoms of water molecules.

Coordination of 9-methylhypoxanthine to [cis-Pt(NH3)2]2+ and [Pt(dien)]2+ as studied by proton NMR

Abstract: Etude du deplacement chimique en RMN du proton pour chaque compose en fonction du pH. Description de la coordination des complexes formes

Synthesis and spectroscopic characterization of transition-metal chelates containing a new hexadentate ligand. Crystal and molecular structure of the heptacoordinated compound (perchlorato-O) [N,N,N',N'-tetrakis(pyrazol-1-ylmethyl)-1,2-diaminoethane]manganese(II) perchlorate

Abstract: Cristallisation du complexe de Mn dans le groupe P2 1 /c. Affinement jusqu'a R=0,046. Environnement octaedrique de Mn, avec deux atomes donneurs fortement lies qu'un seul dans une des positions axiales. Mn est ainsi heptacoordonne (6 N et 1 O qui provient de l'ion perchlorate)

Specific Binding of cis-Platinum Compounds to DNA and DNA Fragments

Abstract: The reaction of cis-PtCl2 (NH3)2 (abbreviated cis-Pt) and related platinum compounds with DNA is believed to be the main cause of the cytostatic activity of such compounds (1–4). After administration the drug is transported through the body. The high Cl- concentration in the blood (5) prevents the hydrolysis of cis-Pt, which is a prerequisite for fast reaction. However, hydrolysis does occur inside the cells after penetration through the cell membrane. The following equilibria are accepted to occur.