Showing papers by "Jan Reedijk published in 1994"

Isotropic Magnetic Exchange Interaction through Double .mu.-1,2,4-Triazolato-N1,N2 Bridges: X-ray Crystal Structure, Magnetic Properties, and EPR Study of Bis(.mu.-3-pyridin-2-yl-1,2,4-triazolato-N',N1,N2)(sulfato-O)aquacopper(II)diaquacopper(II) Trihydrate

Abstract: The crystal and molecular structure of bis(μ-3-pyridin-2-yl-1,2,4-triazolato-N',N1,N2) (sulfato-O)aquacopper(II)-diaquacopper(II) trihydrate (Cu 2 C 14 H 22 N 8 O 10 S; [Cu 2 (pt) 2 (SO 4 )(H 2 O) 3 ] (H 2 O) 3 (1), in which pt is 3-pyridin-2-yl-1,2,4-triazolato) was determined by X-ray diffraction methods. Crystal data for 1: T=298 K, monoclinic, space group=P2 1 /a, a=13.0234(5) A, b=13.4212(6) A, c=14.1119(4) Pd, β=116.462(3) o , Z=4 (dinuclear molecules), and V=2208.2(2) A 3

Binding of 9-Methylhypoxanthine and 9-Ethylguanine to [cis-Ru(2,2'-bipyridine)2]2+. NMR and X-ray Structure of cis-Chlorobis(2,2'-bipyridine)(9-ethylguanine-.kappa.N7)ruthenium(II) Chloride

Abstract: The synthesis and characterization of [cis-Ru(bpy) 2 (9mhyp-κN 7 )L] +/2+ and [cis-Ru(bpy) 2 (9egua-κN 7 )L] +/2+ (bpy=2,2'-bipyridine, 9mhyp=9-methylhypoxanthine, 9egua=9-ethylguanine), where L=Cl - or H 2 O, is reported. Both ions are isolated as chlorides and hexafluorophosphates and show similar proton NMR patterns for the cis-configurated bpy ligands. The aqua complexes (L=H 2 O) have been isolated for both Ru(nucleobase-κN 7 ) complexes as hexafluorophosphate salts

New Antitumor Platinum Compounds Linked to Amino Phosphonic Acids Which Lose the Phosphonate and Tertiary Amine Ligand upon Binding to Nucleic Acids

Abstract: The interaction of the antitumor active platinum phosphonato complexes [cis-Pt(NH 3 ) 2 (ntmp)] and [Pt(R,S-dach)(ntmp)] (ntmp=nitrilotris(methylenephosphonic acid), dach=diaminocyclohexane) with (oligo)nucleotides has been investigated using 1 H NMR and 31 P NMR spectroscopy. For both complexes the formation of GN7,GN7 chelates is observed, together with the release of ntmp. First, the platinum-phosphonate bond is broken, probably by direct attack of the first G-base. The coordination of the second base is accompanied by breakage of the bond between the Pt(II) ion and the tertiary amine ligand, a very unusual observation, as N-donor ligands generally act as nonleaving groups in platinum antitumor chemistry

Names and symbols of transfermium elements (IUPAC recommendations 1994)

Abstract: The Transfermium Working Group (TWG) was set up in 1986 under the joint auspices of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP). Its conclusions, duly endorsed by IUPAC and IUPAP, were published in the following three reports: 1. Criteria that must be satisfied for the discovery of a new chemical element to be recognized, Pure & Appl. Chem., 63, 879-886 (1991). 2. Discovery of the transfermium elements: Introduction to the discovery profiles, Pure & Appl. Chem., 65, 1757-1763 (1993). 3, Discovery of the transfermium elements: Discovery profiles of the transfermium elements, Pure & Appl. Chem., 65, 1764-1814 (1993). IUPAC went a stage further by inviting responses on reports 2 and 3 from the three major groups concerned, i.e., Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung , Darmstadt. These responses together with the TWG's reply to the responses were published unedited in Pure & Appl. Chem., Vol. 65, (1993), pp. 1815-1824.

Sulfur Vulcanization of Simple Model Olefins, Part II: Characterization and Reactivity of Intermediate Vulcanization Products of 2,3-Dimethyl-2-Butene

Abstract: In a study of the mechanism of the sulfur vulcanization of unsaturated rubber, 2,3-dimethyl-2-butene (C6H12) was used as a simple, low-molecular model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8 and the accelerator tetramethylthiuramdisulflde at 140°C for 20 minutes yields a mixture of addition products (C6H11—Sn—C6H11) and also intermediate products (C6H11—Sn—S(S)CN(CH3)2). The formation of C6H11—Sn—C6H11 from these intermediate products only proceeds in the presence of the zinc dimethyldithiocarbamate complex and free alkene.

(2,2'-Biquinoline-κ2N,N')chloro(2,2':6',2''-terpyridine-κ3N,N',N'')ruthenium(II) hexafluorophosphate, [RuCl(C18H12N2)(C15H11N3)][PF6]

Abstract: The coordination geometry about Ru II , involving one Cl and five N atoms, is distorted octahedral and shows several signs of interligand steric interactions. Ru-N distances are in the range 1.970 (7)-2.103 (6) A and the Ru-Cl distance is 2.378 (2) A

Copper-catalyzed oxidative decarboxylation of aliphatic carboxylic acids

Abstract: The copper(11)-catalyzed oxidative decarboxylation of aliphatic carboxylic acids proceeds through an initial inner sphere one- or two-electron transfer, yielding a carboxyl radical or cation respectively. The carboxyl radical resulting from one-electron transfer rapidly decarboxylates, after which the aliphatic radical may react with dioxygen -if present- to a ketone, alcohol or aldehyde. This occurs by Cu(1,11) or H+-catalyzed decomposition of the intermediate (hydro) peroxide. The aliphatic radical can also be oxidized by mononuclear Cu(11) to a carbocation, which yields an ester by reaction with a carboxylic acid (anion), or an alkene by p-H elimination. The carboxylate cation, formed by initial two-electron transfer, can perform an electrophilic attack on an x-C of another carboxylic acid, yielding a new carboxylic acid with an ester group. It can also undergo p-H elimination, yielding an alkene carboxylic acid.

Sulfur Vulcanization of Simple Model Olefins Part III: Vulcanization of 2,3-Dimethyl-2-Butene in the Presence of Different Metal Complexes

Abstract: The mechanism of the sulfur vulcanization of rubber was studied by using 2,3-dimethyl-2-butene (C6H12) as a simple, low-molecular model alkene. Only equivalent allylic positions are present in this alkene. Treating C6H12 with a mixture of ZnO, S8 and the accelerator tetramethylthiuramdisulfide at 140°C yields a mixture of addition products (C6H11—Sn—C6H11). Similar reactions in the presence of various metal oxides instead of zinc oxide show poor vulcanization results. Experiments with various metal dithiocarbamate complexes show a reactivity towards vulcanization in the following sequence: Zn(detc)2>Cd(detc)2>Cu(detc)2>Pb(detc)2>Zn(dmtc)2>Ni(detc)2>Cu(dmtc)2.

Metal coordination by natural biomacromolecules

Abstract: An overview is presented of the role of metal ions in living systems, with special attention to the coordination of the metal ions to the ligands in biologically occurring macromolecules. After a discussion of the commonly occurring ligands in biological systems, the several roles of the metal ions will be discussed (storage & transport, structure generation & stabilisation, catalysis and roles as drugs).

Synthesis of a series of Ni(dmit)/sub 2/ compounds with (methylated) guanidinium as cation. comparison of structures and properties

Abstract: A series of [cation][Ni(dmit) 2 ] 2 compounds was synthesized with (methylated) guanidinium cations of the type C(N(CH 3 ) 2 ) x (NH 2 ) 3–x (x = 0, 1, 2, 3). The crystal structure of all compounds was resolved and the intermolecular orbital overlap integrals were calculated. The conductivity of the compounds was measured from 300-100 K. All compounds behave as semiconductors in this temperature range.

N1,N1-Dimethyl-3-oxopiperazinium(1+) trichloro(dimethyl sulfoxide-S)platinate(1–), (C6H13N2O)[PtCl3(C2H6OS)]

Abstract: The title compound, N 1 ,N 1 -dimethyl-3-oxopiperazinium trichloro(dimethyl sulfoxide-S)platinate(II), (C 6 H 13 N 2 O)(PtCl 3 (C 2 H 6 OS)], was obtained from the reaction of PtCl 2 (dmso) 2 and the chloride salt of N 1 ,N 1 -dimethyl-3-oxopiperazinium (dmpd). The dmpd cation is observed in a conjugated amide form and is hydrogen bonded to the anion via an N-H...O bridge [N...O=3.14 (2) A]