bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monodisperse Oligofluorenes with Keto Defect as Models to Investigate the Origin of Green Emission From Polyfluorenes: Synthesis, Self‐Assembly, and Photophysical Properties
Authors: Chi Chunyan , Im Chan , Enkelmann Volker , Ziegler Andreas , Lieser Günter , Wegner Gerhard 
Published: August 2005

AbstractOligofluorenes (a trimer, pentamer, and heptamer) with one fluorenone unit in the center (OFnK: n=3, 5, or 7) were synthesized and used as models to understand the origin of the low‐energy emission band in the photoluminescence and electroluminescence spectra of some polyfluorenes. All compounds form glasses with Tg at 30 °C (OF3 K), 50 °C (OF5 K) and 57 °C (OF7 K). Oligomers OF5 K and OF7 K exhibit smectic liquid crystal phases that undergo transition to isotropic melts at 107 and 205 °C, respectively. Oligomer OF5 K could be obtained in form of single crystals. The X‐ray structure analysis revealed the helical nature of the molecule and a helix reversal defect located at the central fluorenone unit. The packing pattern precludes formation of excimers. Electrochemical properties were investigated by cyclic voltammetry. The ionization potential (Ip) and electron affinity (Ea) were calculated from these data. Studies of the photophysical properties of OFnK in solution and thin film by steady‐state and time‐resolved fluorescence spectroscopic measurements suggest efficient funneling of excitation energy from the photoexcited fluorene segments to the low‐energy fluorenone sites by both intra‐ and intermolecular hopping events whereby they give rise to green emission. Intermolecular energy transfer was investigated by using a model system composed of a highly defect free polyfluorene PF2/6 doped by OFnK. Förster‐type energy transfer takes place from PF2/6 to OFnK. The energy‐transfer efficiency increases predictably with increasing concentration of OFnK.
Controlling Metal–Ligand–Metal Oxidation State Combinations by Ancillary Ligand (L) Variation in the Redox Systems [L2Ru(μ‐boptz)RuL2]n, boptz=3,6‐bis(2‐oxidophenyl)‐1,2,4,5‐tetrazine, and L=acetylacetonate, 2,2′‐bipyridine, or 2‐phenylazopyridine
Authors: Patra Srikanta , Sarkar Biprajit , Maji Somnath , Fiedler Jan , Urbanos Francisco A. , Jimenez‐Aparicio Reyes , Kaim Wolfgang , Lahiri Goutam Kumar 
Published: August 2005

AbstractThe new compounds [(acac)2Ru(μ‐boptz)Ru(acac)2] (1), [(bpy)2Ru(μ‐boptz)Ru(bpy)2](ClO4)2 (2‐(ClO4)2), and [(pap)2Ru(μ‐boptz)Ru(pap)2](ClO4)2 (3‐(ClO4)2) were obtained from 3,6‐bis(2‐hydroxyphenyl)‐1,2,4,5‐tetrazine (H2boptz), the crystal structure analysis of which is reported. Compound 1 contains two antiferromagnetically coupled (J=−36.7 cm−1) RuIII centers. We have investigated the role of both the donor and acceptor functions containing the boptz2− bridging ligand in combination with the electronically different ancillary ligands (donating acac−, moderately π‐accepting bpy, and strongly π‐accepting pap; acac=acetylacetonate, bpy=2,2′‐bipyridine pap=2‐phenylazopyridine) by using cyclic voltammetry, spectroelectrochemistry and electron paramagnetic resonance (EPR) spectroscopy for several in situ accessible redox states. We found that metal–ligand–metal oxidation state combinations remain invariant to ancillary ligand change in some instances; however, three isoelectronic paramagnetic cores Ru(μ‐boptz)Ru showed remarkable differences. The excellent tolerance of the bpy co‐ligand for both RuIII and RuII is demonstrated by the adoption of the mixed‐valent form in [L2Ru(μ‐boptz)RuL2]3+, L=bpy, whereas the corresponding system with pap stabilizes the RuII states to yield a phenoxyl radical ligand and the compound with L=acac− contains two RuIII centers connected by a tetrazine radical‐anion bridge.
Proteomics of Metal Transport and Metal‐Associated Diseases
Authors: Kulkarni Prasad P. , She Yi Min , Smith Scott D. , Roberts Eve A. , Sarkar Bibudhendra 
Published: August 2005

AbstractProteomics technology has the potential to identify groups of proteins that have similar biological function. However, few attempts have been made to identify and characterize metal‐binding proteins by using proteomics strategies. Many transition metals are essential to sustain life. Copper, iron, and zinc are the most abundant transition metals relevant to biological systems. In addition to their important biological functions, metals can also catalyze the formation of damaging free radical species. Hence, their intracellular transport is tightly regulated. Despite recent insights into the intracellular transport of copper and other metals, our overall understanding of intracellular metal metabolism remains incomplete and it is likely that many metal‐binding proteins remain undiscovered. Furthermore, the protein targets for metals during metal‐associated disease states or during exposure to toxic levels of environmental metals are yet to be unravelled. A proteomics strategy for the analysis of metal‐transporting or metal‐binding proteins has the potential to uncover how a large number of proteins function in normal or metal‐associated diseased states. Here we discuss the principal aspects of metal metabolism, and the recent developments in the area of the proteomics of metal transport.
Hydrogenation of the Ternary Silicides LnNiSi (Ln: Ce, Nd) Crystallizing in the Tetragonal LaPtSi‐Type Structure.
Authors: Pasturel M. , Weill F. , Bouree F. , Bobet J.‐L. , Chevalier B. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and NIR‐to‐Violet, Blue, Green, Red Upconversion Fluorescence of Er3+: LaOBr.
Authors: Wang Dianyuan , Guo Yanyan , Zhang Ende , Chao Xingbing , Yu Lisheng , Luo Jianglong , Zhang Weiping , Yin Min 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Phase Relations in the Quasi‐Binary Cu2GeS3—ZnS and Quasi‐Ternary Cu2S—Zn(Cd)S—GeS2 Systems and Crystal Structure of Cu2ZnGeS4.
Authors: Parasyuk O. V. , Piskach L. V. , Romanyuk Y. E. , Olekseyuk I. D. , Zaremba V. I. , Pekhnyo V. I. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Chemical Activation of MgH2; a New Route to Superior Hydrogen Storage Materials.
Authors: Johnson Simon R. , Anderson Paul A. , Edwards Peter P. , Gameson Ian , Prendergast James W. , Al‐Mamouri Malek , Book David , Harris I. Rex , Speight John D. , Walton Allan 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Dodecahydro‐closo‐dodecaborate Halides of the Heavy Alkali Metals with the Formula M3X[B12H12] (M: K—Cs, NH4; X: Cl and Br)
Authors: Tiritiris Ioannis , Weidlein Johann , Schleid Thomas 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Asymmetric Henry Reaction Catalyzed by C2‐Symmetric Tridentate Bis(oxazoline) and Bis(thiazoline) Complexes: Metal‐Controlled Reversal of Enantioselectivity.
Authors: Du Da‐Ming , Lu Shao‐Feng , Fang Tao , Xu Jiaxi 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Dipolar Cycloaddition of Carbonyl Ylides Generated from Methyl cis‐2‐Diazoacetyl‐1‐cyclopropanecarboxylates.
Authors: Molchanov A. P. , Diev V. V. , Kopf J. , Kostikov R. R. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Catalytic Action of Thiarylstibanes: Oxidation of Benzoins into Benzyls Using Triarylstibanes under an Aerobic Condition.
Authors: Yasuike Shuji , Kishi Yoshihito , Kawara Shin‐ichiro , Kurita Jyoji 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Development of a Novel Method for the Preparation of Dithioacetal in the Presence of Titanium(IV) Chloride/Zinc in Dimethoxymethane.
Authors: Lee Ji‐Hyun , Jeong Hyung Jae , Jin Chung Keun , Jang Sang Hun , Kim Min Kyu , Yoon Yong‐Jin , Lee Sang‐Gyeong 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of 2‐Chloro‐1,1‐difluoroallyl Mesylates Through Novel Rearrangement and C—C Bond Formation by Their Pd‐Catalyzed Reaction with Diethylzinc.
Authors: Ando Akira , Nishihara Masakazu , Sato Kazuyuki , Omote Masaaki , Kumadaki Itsumaro 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Regular Trends in Nucleophilic Substitutions in 2‐Alkylamino‐4‐chloronitrobenzenes.
Authors: Zotova N. V. , Kushakova P. M. , Kuznetsov V. A. , Rodin A. A. , Garabadzhiu A. V. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
A New Method for the Synthesis of Acyltitanium Complexes and Their Application to Copper‐Mediated Acylmetalation of Carbon—Carbon Multiple Bonds in Aqueous Media.
Authors: Han Zhenfu , Fujioka Takuma , Usugi Shin‐ichi , Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Reactions of N‐(Perfluorophenyl)carbonimidoyl Dichloride with Aromatic Acids and Their Derivatives in the Presence of AlCl3. Formation of 2‐(Perfluorophenyl)isoindoline‐1,3‐dione and Its Derivatives.
Authors: Petrova T. D. , Platonov V. E. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Solvent‐Free Mechanochemical and One‐Pot Reductive Benzylizations of Malononitrile and 4‐Methylaniline Using Hantzsch 1,4‐Dihydropyridine as the Reductant.
Authors: Zhang Ze , Gao Jie , Xia Jing‐Jing , Wang Guan‐Wu 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Enantioselective Nitrile Anion Cyclization to Substituted Pyrrolidines. A Highly Efficient Synthesis of (3S,4R)‐N‐tert‐Butyl‐4‐arylpyrrolidine‐3‐carboxylic Acid
Authors: Chung John Y. L. , Cvetovich Raymond , Amato Joseph , McWilliams J. Christopher , Reamer Robert , DiMichele Lisa 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
An Efficient One‐Pot Synthesis of Pyrrolines and Tetrahydropyridines from Their Chloro‐Precursors via in situ Aza‐Wittig Reaction.
Authors: Singh Pradeep N. D. , Klima Rodney F. , Muthukrishnan Sivaramakrishnan , Murthy Rajesh S. , Sankaranarayanan Jagadis , Stahlecker Heidi M. , Patel Bhavika , Gudmundsdottir Anna D. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis, Oxidative Transformation and Biological Activity of Sulfur‐Containing Cyclic Acetals.
Authors: Abdrakhmanova A. R. , Kabal'nova N. N. , Shereshovets V. V. , Rol'nik L. Z. , Yagafarova G. G. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Spirocyclic 4,5,5a,6,7,8‐Hexahydro‐1H‐pyrazolo[3,4‐e]indolizine Derivatives.
Authors: Eltsov Oleg S. , D'yachenko Elisaveta V. , Glukhareva Tatiana V. , Morzherin Yury Yu. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Antibacterial Activity of Dihydro‐1,2‐oxazine and 2‐Pyrazoline Oxazolidinones: Novel Analogues of Linezolid.
Authors: D'Andrea Stan , Zheng Zhizhen Barbara , DenBleyker Kenneth , Fung‐Tomc Joan C. , Yang Hyekyung , Clark Junius , Taylor Dennis , Bronson Joanne 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Syntheses of New Difluoromethylene Benzoxazole and 1,2,4‐Oxadiazole Derivatives, as Potent Non‐Nucleoside HIV‐1 Reverse Transcriptase Inhibitors.
Authors: Medebielle Maurice , Ait‐Mohand Samia , Burkhloder Conrad , Dolbier William R. Jr. , Laumond Geraldine , Aubertin Anne‐Marie 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Discovery of 2‐Aminothiazole‐4‐carboxamides, a Novel Class of Muscarinic M3 Selective Antagonists, Through Solution‐Phase Parallel Synthesis.
Authors: Sagara Yufu , Mitsuya Morihiro , Uchiyama Minaho , Ogino Yoshio , Kimura Toshifumi , Ohtake Norikazu , Mase Toshiaki 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Unusual Reaction of 1,3‐Thiazole‐2‐thiones with N‐(O‐Nitrophenyl)‐C‐Substituted Nitrile Imines.
Authors: Budarina E. V. , Dolgushina T. S. , Petrov M. L. , Bel'skii V. K. , Labeish N. N. , Kol'tsov A. A. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
1,4‐ and 2,4‐Substituted‐1,2,3‐triazoles as Potential Potassium Channel Activators. Part 7.
Authors: Calderone Vincenzo , Giorgi Irene , Livi Oreste , Martinotti Enrica , Martelli Alma , Nardi Antonio 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Substituted Coumarin Amidines: Useful Building Blocks for the Preparation of [1]Benzopyrano[4,3‐b]pyridin‐5‐one and [1]Benzopyrano[4,3‐d]pyrimidin‐5‐one Derivatives.
Authors: Beccalli Egle M. , Contini Alessandro , Trimarco Pasqualina 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Properties of 3‐Acyl‐γ‐pyrones, a Novel Class of Flavones and Chromones.
Authors: Ganguly A. K. , Kaur S. , Mahata P. K. , Biswas D. , Pramanik B. N. , Chan T. M. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Intramolecular Diels—Alder Reaction of α‐Fluoroacrylate Derivatives Promoted by Novel Bidentate Aluminum Lewis Acid.
Authors: Saito Akio , Yanai Hikaru , Sakamoto Wataru , Takahashi Kosuke , Taguchi Takeo 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
2‐R‐6‐Ethyl‐7‐hydroxy‐3‐(5‐phenyl‐1,3,4‐thiadiazolyl‐2)chromones.
Authors: Shokol T. V. , Semenyuchenko V. V. , Khilya V. P. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Asymmetrized Tris(hydroxymethyl)methane as a Precursor of N‐ and O‐Containing 6‐Membered Heterocycles Through Ring‐Closing Metathesis.
Authors: Banfi Luca , Guanti Giuseppe , Paravidino Monica , Riva Renata 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Microwave‐Assisted Solvent‐Free Synthesis of 3‐[(4‐Substituted Piperazin‐1‐yl)alkyl] Imidazo[2,1‐b][1,3]benzothiazol‐2(3H)‐ones as Serotonin3 (5‐HT3) Receptor Antagonists.
Authors: Mahesh R. , Perumal R. Venkatesha , Pandi P. V. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Fused Heterocyclic Systems with s‐Triazine Ring. Part 2. Synthesis and Biological Activity of Fluorinated 2‐Amino‐4‐aryl‐3,4‐dihydro[1,3,5]triazino[1,2‐a]benzimidazoles.
Authors: Dolzhenko Anton V. , Chui Wai‐Keung , Dolzhenko Anna V. , Chan Lai‐Wah 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Alkenyl‐ and Aryl[2‐(hydroxymethyl)phenyl]dimethylsilanes: An Entry to Tetraorganosilicon Reagents for the Silicon‐Based Cross‐Coupling Reaction.
Authors: Nakao Yoshiaki , Imanaka Hidekazu , Sahoo Akhila K. , Yada Akira , Hiyama Tamejiro 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Reactions in the Chrysenequinone—Phenylacetylene—Phosphorus Trichloride System: Formation and Crystal Structure of 2,7‐Dichloro‐2‐oxo‐4‐phenylbenzo[o]‐1,2‐oxaphosphatriphenylene.
Authors: Bogdanov Andrey V. , Mironov Vladimir F. , Krivolapov Dmitry B. , Litvinov Igor A. , Musin Rashid Z. , Latypov Shamil K. , Konovalov Alexander I. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Regioselective Chlorination of 4‐ and 5‐Methyl‐2,2,2‐trichlorobenzo[d]‐1,3,2‐dioxaphospholes.
Authors: Varaksina Elena N. , Mironov Vladimir F. , Shtyrlina Alfia A. , Dobrynin Alexey B. , Litvinov Igor A. , Konovalov Alexander I. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Vigulariol, a New Metabolite from the Sea Pen Vigularia juncea
Authors: Su Jui‐Hsin , Huang Ho‐Cheng , Chao Chih‐Hua , Yan Liang‐Yu , Wu Yang‐Chang , Wu Chin‐Chung , Sheu Jyh‐Horng 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Methyl ent‐16α‐Dichlorophosphitobeyeran‐19‐oate as the First Example of Phosphorylated Diterpenoid Derivatives of the Beyerane Series.
Authors: Mamedova Vera L. , Nikitina Kristina A. , Mamedov Vakhid A. , Kataev Vladimir E. , Alfonsov Vladimir A. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Dynamic Kinetic Resolution of α‐Chloro Esters in Asymmetric Nucleophilic Substitution Using Diacetone‐D‐glucose as a Chiral Auxiliary.
Authors: Kim Hyun Jung , Shin Eun‐kyoung , Chang Ji‐yeon , Kim Yongtae , Park Yong Sun 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
New Heterocyclic Derivatives of 2‐Amino‐1,6‐anhydro‐2‐deoxy‐β‐D‐glucopyranose Containing 1,4‐Oxazepane or Azepane Ring.
Authors: Trtek Tomas , Cerny Miloslav , Budesinsky Milos , Trnka Tomas , Cisarova Ivana 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Stereoselective Synthesis of C1‐C5 and C4‐C5 Linked Deoxy Disaccharides via a Ring Closing Metathesis Protocol.
Authors: Sharma G. V. M. , Begum Asra , Kumar K. Raman , Krishna Palakodety Radha , Prabhakar A. , Kunwar A. C. 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Identification and Antibacterial Activity of a New Oleandomycin Derivative from Streptomyces antibioticus.
Authors: Kim Beom Seok , Oh Hyuncheol , Kim Sun Young , Park Jeong Ah , Yoon Yeo Joon , Lee Sang Kil , Kim Bo Yeon , Ahn Jong Seog 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Prunustatin A, a Novel GRP78 Molecular Chaperone Down‐Regulator Isolated from Streptomyces violaceoniger.
Authors: Umeda Yukiko , Chijiwa Shuhei , Furihata Kazuo , Furihata Keiko , Sakuda Shohei , Nagasawa Hiromichi , Watanabe Hidenori , Shin‐ya Kazuo 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Deoxyverrucosidin, a Novel GRP78/BiP Down‐Regulator Produced by Penicillium sp.
Authors: Choo Soo‐Jin , Park Hae‐Ryong , Ryoo In‐Ja , Kim Jong‐Pyung , Yun Bong‐Sik , Kim Chang‐Jin , Shin‐ya Kazuo , Yoo Ick‐Dong 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Myrothenones A and B, Cyclopentenone Derivatives with Tyrosinase Inhibitory Activity from the Marine‐Derived Fungus Myrothecium sp.
Authors: Li Xifeng , Kim Min Kyung , Lee Uk , Kim Se‐Kwon , Kang Jung Sook , Choi Hong Dae , Son Byeng Wha 
Published: August 2005

AbstractFor Abstract see ChemInform Abstract in Full Text.
Gastrointestinal stromal tumor: 5 years later
Authors: van der Zwan Sanne M. , DeMatteo Ronald P. 
Published: September 2005

AbstractThere is now considerable interest in gastrointestinal stromal tumor (GIST) because it can be treated effectively with a targeted molecular agent. The majority of GISTs contain an activating mutation in the KIT protooncogene or, occasionally, in the platelet‐derived growth factor‐α (PDGFRA) gene. Five years ago, imatinib mesylate, a specific molecular inhibitor of the protein products of these 2 genes, was applied to metastatic GIST. Approximately 80% of patients with metastatic GIST benefit from imatinib, although acquired resistance to the agent may develop. For patients with primary GIST, surgery remains the treatment of choice, and whether outcome is improved by adjuvant imatinib is currently under broad investigation. A combination of imatinib therapy and surgery also may be effective in a subset of patients with metastatic or unresectable primary GIST. In this review, the authors summarize the new multimodality approach to GIST. The integration of surgery and molecular therapy in GIST will serve as a prototype for the management of other solid tumors for which targeted agents become available. Cancer 2005. © 2005 American Cancer Society.
Tuning of Copper(I)–Dioxygen Reactivity by Bis(guanidine) Ligands
Authors: Herres‐Pawlis Sonja , Flörke Ulrich , Henkel Gerald 
Published: August 2005

AbstractA series of bis(guanidine) ligands designed for use in biomimetic coordination chemistry, namely bis(tetramethylguanidino)‐, bis(dipiperidinoguanidino)‐, and bis(dimethylpropyleno)propane (btmgp, DPipG2p and DMPG2p, respectively), has been extended to include bis(dimethylethyleneguanidino)propane (DMEG2p), which has both Namine atoms of each guanidine functionality connected by a short ethylene bridge, as a member. From this series, a family of novel bis(guanidine)copper(I) compounds – [Cu2(btmgp)2][PF6]2 (1), [Cu2(DPipG2p)2][PF6]2 (2), [Cu2(DMPG2p)2][PF6]2 (3), and [Cu2(DMEG2p)2][PF6]2·2MeCN (4) – has been synthesised. Single‐crystal X‐ray analysis of 1–4 demonstrated that these compounds contain dinuclear complex cations that contain twelve‐membered heterocyclic Cu2N4C6 rings with the Cu atoms being more than 4 Å apart. Each copper atom is surrounded by a set of two N‐donor functions from different ligands, resulting in linear N–Cu–N coordination sites. Depending on their individual substitution patterns, the guanidine moieties deviate from planarity by characteristic propeller‐like twists of the amino groups around their N–Cimine bonds. The influence of these groups on the reactivity of the corresponding complexes 1–4 with dioxygen was investigated at low temperatures by means of UV/Vis spectroscopy. The reaction products can be classified into μ‐η2:η2‐peroxodicopper(II) or bis(μ‐oxo)dicopper(III) complex cations that contain the {Cu2O2}2+ core portion as different isomers. The electronic properties of the specific bis(guanidine) ligands are discussed from the viewpoint of their σ‐donor and π‐acceptor capabilities, and it is shown that μ‐η2:η2‐peroxodicopper(II) complexes are stabilised relative to the bis(μ‐oxo)dicopper(III) ones if π conjugation within the guanidine moieties is optimised. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stable Nickel Catalysts for Fast Norbornene Polymerization: Tuning Reactivity
Authors: Casares Juan A. , Espinet Pablo , Martín‐Alvarez José M. , Martínez‐Ilarduya Jesús M. , Salas Gorka 
Published: August 2005

AbstractThe air‐stable complexes trans‐[Ni(C6Cl2F3)2L2] (L = SbPh3, 1; AsPh3, 2; AsCyPh2, 3; AsMePh2, 4; PPh3, 5) have been synthesized by arylation of [NiBr2(dme)] (dme = 1,2‐dimethoxyethane) in the presence of the corresponding ligand L (for compounds 1–4) or by ligand substitution starting from 1 (for compound 5). The structures of 1, 2, and 5 have been determined by X‐ray diffraction and show an almost perfect square‐planar geometry in all cases. Their catalytic activity in insertion polymerization of norbornene have been tested showing a strong dependence of the yield and molecular mass of the polymer on the ligand used and the solvent. High yield and high molecular mass values are obtained using complexes with ligands easy to displace from NiII (SbPh3 is the best) and noncoordinating solvents. Complexes 1–3 are suggested as convenient bench‐catalysts to have available in the lab. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)