bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscosity and conformation of calf thymus histones
Authors: Jirgensons B. , Hnilica L. S. , Capetillo S. C. 
Published: April 2003

AbstractThe gross conformation of the four main histone fractions was determined from viscosity measurements in aqueous solutions and in solutions containing inorganic electrolytes. In distilled water the histones behaved like flexible linear polyelectrolytes, i.e. the reduced specific viscosity increased with dilution exponentially. In the presence of acid or salts, the viscosity decreased and the normal linear dependence of the reduced specific viscosity on concentration was observed. The viscosity of the very lysine‐rich Fraction 1 (which is also relatively rich in proline) was much higher than that of the other histone fractions. Phosphate and sulfate ions were more effective in diminishing the viscosity of aqueous solutions of the Fraction 1 than chloride or acetate ions.
Linear oligotrimethyleneurethans. Oligourethans. III1
Authors: Iwakura Yoshio , Hayashi Katsumi , Iwata Kaoro 
Published: April 2003

AbstractDuring the course of a serial work of linear oligourethans, oligotrimethyleneurethans, A[O(CH2)3NHCO]nOCH3 (A = acetyl or H) were synthesized up to the pentamer. The synthesis was achieved by the stepwise addition of 3‐acetoxypropyl isocyanate with a preceding hydroxy terminated oligomer.
Über die synthese methylsubstituierter p‐oligophenylene durch oxydative verknüpfung aus lithiumorganischen verbindungen. 19. Mitteilung über poly‐ und oligophenylene1
Authors: Heitz Von W. , Ullrich R. 
Published: April 2003

AbstractDie oxydative Verknüpfung von Lithiumarylen wurde an den isomeren Lithiumtoluylen als Modellverbindungen studiert. Die Darstellung von 4,4′‐Dilithium‐3,3′‐dimethylbiphenyl und von 11,44‐Dilithium‐12,23,32,43‐tetramethyl‐p‐quaterphenyl wird beschrieben.Die oxydative Polykondensation dieser Dilithiumverbindungen mit Hilfe von CuCl2 wurde in verschiedenen Lösungsmitteln untersucht. Als Hauptreaktionsprodukte entstehen die erwarteten Verbindungen mit 8 bis 12 p‐verknüpfte Phenylenbausteine.Aus dem Reaktionsgemisch wurde das 12,233,2,435,2,63,72,83,92,103,112,123‐Dodekamethyl‐p‐duodeciphenyl durch präparative Dünnschichtchromatographie in hoher Reinheit isoliert.Die Darstellung des 12,23,32,43,52,63,72,83‐Oktamethyl‐p‐octiphenyls gelang aus 11‐Lithium‐12,23,32,43‐tetramethyl‐‐p‐ quaterphenyl ebenfalls mit Hilfe von CuCl2.
Anionic telomerizations of butadiene with aromatic hydrocarbons. IV. Molecular weight distributions of the telomers
Authors: Kume Shouji 
Published: April 2003

AbstractThe molecular weight distribution of telomers, prepared from butadiene by sodium in toluene/tetrahydrofuran mixtures was investigated. This polymerization involves only one kind of termination chain transfer to toluene. Therefore the mole distribution function f(x) is described by:

and the weight distribution h(x) by:

where:

α is a coefficient, and P̄n represents the number‐average degree of polymerization. These two distribution functions were confirmed by fractionations of the prepared telomers.
Molekulargewichtsbestimmung des kallikrein‐inaktivators mittels der ultrazentrifuge
Authors: Scholtan Von W. , Lie Sie Ying 
Published: April 2003

AbstractDas Molekulargewicht des Kallikrein‐Inaktivators (KI) wurde mittels der Ultrazentrifugenmethode nach ARCHIBALD und TRAUTMANN bestimmt. Das Molekulargewicht der hoch gereinigten Präparate ist vom pH der Lösung und von der Konzentration unabhängig und beträgt 6500 ± 200.Aus Sedimentations‐, Diffusions‐ und Viskositätsmessungen ergibt sich, daß das Molekül des KI eine merklich von der Kugelform abweichende Gestalt besitzt.Der KI bildet nicht nur mit Enzymen, sondern auch mit niedermolekularen Stoffen Assoziate; solche Stoffe sind z. B.: Purine, Pyrimidine, ADP, ATP und in geringem Maßemehrwertige Anionen (z. B. Citronensäure, Pyro‐ und Metaphosphorsäure). Die zweiwertigen Kationen des Calciums, Magnesiums und Zinks bewirken dagegen keine Dimerisierung.Die Wechselwirkung des KI mit den niedermolekularen Stoffen ist eine Gleichgewichts‐reaktion und folgt dem Massenwirkungsgesetz.Gleichungen für die Abhängigkeit des mittleren Molekulargewichts und des Assoziationsgrades von der Eiweißkonzentration und der Konzentration des Komplexbildners werden aufges ellt. Die Gleichgewichtskonstante der Assoziationsreaktion wird für Adenin und Thymin ermittelt.Aus TRAUTMANN‐Diagrammen wurde beim isoelektrischen Punkt des KI (pH 10, 5) die Molekulargewichtsverteilung ermittelt. Die früher untersuchten Präparate enthalten in 1‐proz. wäßriger Lösung vor allen Moleküle vom Molekulargewicht 6500, in geringer Menge ferner Assoziate vom Molekulargewicht 13000.Durch Dialyse und Gelfiltration ist eine Fraktionierung und partielle Trennung der Komponenten möglich.In den bereits früher untersuchten Präparaten wurde ein Stoff mit einem adenosinähnlichen UV‐Spektrum gefunden, der in sehr kleiner Konzentration eine Assoziation des KI bewirkt. Das Molekulargewicht dieser unreinen Präparate ist daher sowohl vom pH der Lösung als auch von der Konzentration abhängig. In saurer und alkalischer Lösung besitzen diese Präparate ein Mindest‐Molekulargewicht; in neutraler Lösung erreicht das Molekulargewicht einen maximalen Wert.Beim Verdünnen einer neutralen Lösung dieser Präparate verringert sich das Molekulargewicht bei Konzentrationen unter 0,2% und nähert sich dem Wert 6500. In alkalischer Lösung bei pH 12,5 nimmt das Molekulargewicht mit der Zeit zu und erreicht nach einigen Tagen einen konstanten maximalen Wert von 13000. Die durch pH‐Änderungen verursachten Molekulargewichtsänderungen sind im pH‐Bereich von 1,l bis 10,5 vollständig reversibel, über pH 12 dagegen teilweise irreversibel.
Polymerisation of tetrahydrofuran (part II)
Authors: Sims D. 
Published: April 2003

AbstractThe polymerisation of tetrahydrofuran with phosphorus pentafluoride has been studied in bulk and in ethyl ether solution. The rate of polymerisation increases rapidly with time and for solutions in ether, having a monomer concentration not greatly above the equilibrium monomer concentration, it was not possible to follow the reaction to completion since the reaction mixture became too viscous. The effect of small additions of water to the system has been studied and it was found that the rate of polymerisation at a particular time t, \documentclass{article}\pagestyle{empty}\begin{document}$- \left( {\frac{{dM}}{{dt}}} \right)_t$\end{document} goes through a maximum as the concentration of water is increased. Some information was obtained on the way the rate of polymerisation at the beginning of the reaction depends on [M], [PF5], and time.
Crystalline copolymers of 3‐methyl butene‐1 and alkyl substituted 2,7‐octadienes
Authors: DiPietro J. , DiEdwardo A. 
Published: April 2003

AbstractCrystalline copolymers of 3‐methylbutene and 2,4‐dimethyl‐2,7‐octadiene and 2,6‐dimethyl‐2,7‐octadiene, respectively, were obtained in yields of 28 40%. The copolymers, which were prepared in n‐heptane with ZIEGLER‐NATTA catalysts at 25°C. were insoluble in chlorinated organic solvents, had sharp, crystalline melting points and were melt‐spun into fibers. Quantitative analysis of the substituted double bond present in these copolymers were made by the bromination reaction and by use of the molar absorptivity of the R′CHCR′′R′′′ unsaturation using the 2,4‐dimethyl‐2,7‐octadiene polymer as reference. The Chemical structure of these copolymers has been documented by their X‐ray diagrams and infrared spectra.
Über die homogene und heterogene acetylierung von polyformaldehyd. 28. Mitteilung über polyoxymethylene1
Authors: Deibig Von H. , Hücker H. , Jaacks V. , Kern W. 
Published: April 2003

AbstractDie Acetylierung der Endgruppen eines hochmoleckularen Polyoxymethylendiols mit Essigsäureanhydrid wurde bei 200°C in Substanz sowie bei 135°C in Lösung und in Suspension untersucht. Die Umsetzung ist in homogenem Medium innerhalb kurzer Zeit praktisch vollständig; bei 200°C erfolgt jedoch ohne Zusatz eines (tertiären) Amins eine besonders starke Verminderung der Molekulargewichte und ein Verlust an Polymerem durch Bildung flüssiger Oligo‐oxymethylendiacetate. Eine fast quantitative Acetylierung ohne Molekulargewichtsverminderung ist durch Umsetzung bei 135°C in Lösung unter Zusatz eines tertiären Amins möglich.Die Veresterungsgeschwindigkeit bei 135°C ist in heterogenem Medium wesentlich kleiner als in Lösung, und etwa 5% der Hydroxylendgruppen sind dieser Acetylierung nur sehr schwer zugänglich. Es wird angenommen, daß dieser geringe Teil der Endgruppen in besonders gut ausgebildeten kristallinen Bereichen eingeschlossen ist, während sich der weitaus größte Teil der Endgruppen in amorphen Bereichen oder in gestörten Kristalliten befindet, welche für das Acetylierungsreagenz zugänglich sind. Polykondensate aus wärigen Formaldehydlösungen besitzen gemäß Röntgenbeugungsuntersuchungen fast keine amorphen Berciche und viel weniger gestörte Kristallite als Polymerisate aus dem wasserfreien Monomeren; sie konnten daher nicht heterogen acetyliert werden. Durch vorhergehendes Umfällen des Polyoxymethylendiols, durch mechanische Zerkleinerung order durch Einwirkung von Ultraschall kann die Geschwindigkeit der heterogenen Acetylierung wesentlich erhöht werden.
Zum mechanismus der thermischen chlorwassmtoffabspaltung aus polyvinylchlorid. 3. Mitt. Über die länge der polyensequenzen in partiell dehydrohalogenierten poiyvinylchloriden, polyvinylbromiden und vinylchlorid‐copolymeren
Authors: Braun Von Dietrich , Thallnaier Manfred 
Published: April 2003

AbstractDie bei der thermischen Halogenwasserstoffabspaltung aus Polyvinylhalogeniden in den Polymeren entstehenden Polyensequenzen wurden mit Hilfe der Elektronenspektren analysiert. Unter Zugrundelegung der für Polyenspektren allgemein gültigen Gesetzmäßigkeiten konnte die Verteilung, der Polyensequenzlängen in abgebautem Polyvinylchlorid (PVC), Polyvinylbromid (PVBr) sowie in Vinylchlorid‐Fumarsäurediäthylester‐ und Vinylchlorid‐Isobutylen‐Copolymeren näherungsweise ermittelt werden.Während in abgebautem PVC die Häufigkeit der Sequenzen mit zunehmender Zahl an konjugierten Doppelbindungen kontinuierlich abnimmt, sind in abgebautem PVBr mittlere Sequenzlängen mit etwa 12 bis 13 Doppelbindungen gegenüber kürzeren und längeren am häufigsten vertreten; in den abgebauten Copolymeren treten mit abnehmendem Vinylchloridanteil längere Polyensequenzen seltener auf. Die längsten Polyensequenzen in abgebautem PVC besitzen ca. 25 bis 30, in abgebautem PVBr ca. 40 bis 45 Doppelbindungen.Beim PVC nimmt mit der Dauer des Abbaus bzw. mit dem Umsatz die Polyenkonzentration im Verhältnis zur abgespaltenen Chlorwasserstoffmenge ab. Die Häufigkeitsverteilung verschiebt sich dabei merklich zugunsten der kürzeren Sequenzen, was auf das bevorzugte Verschwinden der längeren Polyensequenzen durch Sekundärreaktionen zurückgeführt wird.
Cationic polymerization of isobutyl vinyl ether catalyzed by ion exchange resin (polystyrene sulfonic acid)
Authors: Aoki Shuzo , Otsu Takayuki , Imoto Minoru 
Published: April 2003

AbstractThe Catalytic activity of polystyrene sulfonic acid (commercial cation exchange resin) has been investigated for the cationic polymerization of vinyl monomers. Styrene, α‐methylstyrene, and isobutyl vinyl ether polymerized in the presence of this cation exchange resin giving polymers with rather low molecular weights. The kinetic behaviour of polymerization of isobutyl vinyl ether is similar to that observed in the sulfuric acid‐catalyzed polymerization of styrene, but a diffusion‐controlled mechanism is proposed for the propagation reaction. The resulting poly(isobutyl vinyl ether) has an isotactic structure.
Etude de la cristallisation des polymères I. Structure lamellaire de polyoxyéthylènes de faible masse moléculaire
Authors: Arlif J. P. , Spegt P. A. , Skoulios A. E. 
Published: April 2003

AbstractSeven low molecular weight polyethyleneoxide samples have been studied by means of low‐angle X‐ray diffraction technique and dilatometry.The thickness of the crystalline lamellae of the polymer has been found exactly to correspond to the known length of the full extended polymer chains, the gap between the lamellae being of the order of 7 Å.The relationship between the experimental value of molar volume and the molecular weight has been established and the specific volume of crystalline polyethyleneoxide has been deduced.Near the melting temperature of the polymer a fractionation effect has been found to occur and its dependance upon the crystallization temperature has been examined.
Über polymere methylierte vinyi‐hydrochinone
Authors: Manecke Von G. , Bourwieg G. 
Published: April 2003

AbstractDie radikalische Homopolymerisation verschieden methylierter Vinylhydrochinon‐Verbindungen wurde untersucht. Durch Copolymerisation von 1‐Vinyl‐2,4‐dimethyl‐3,6‐diacetoxy‐benzol mit Styrol und Divinylbenzol und sulfonierung der Polymerisate wurden Redoxharze erhalten. Die Austauschkapazität, die Redoxkapazität, die Quellungs eigenchaften und die Reaktionsgeschwindigkeit sowie das Redoxpotential wurden gemessen und die Werte untereinander in Beziehung gesetzt.
Thermoelastieity of rubber vulcanizates. I
Authors: Yamamoto Kazuhiko , Kusamizu Sumio , Fujita Hiroshi 
Published: April 2003

AbstractA new method for evaluating the temperature coefficient of the unperturbed dimensions <r2>0 of a polymer chain from stress‐temperature data was proposed assuming that the parameter C1 in the MOONEY‐RIVLIN equation (f = (C1 + C2/α)(α−1/α2), where f is the tensile force and α the elongation ratio) has the same form as the factor in the f vs. α relation predicted by the current theory of GAUSSIAN networks. Precise stress‐temperature measurements were performed for two cis‐1,4‐polybutadiene vulcanizates and one natural rubber vulcanizate, and the results were analyzed by the new equation and also by the familiar FLORY equation. The latter equation led to dln<r2>0/dT (T is the absolute temperature) which decreased with increasing α, as had been observed for many crosslinked polymers by previous workers. The new equation, on the other hand, gave values which were actually independent of α. These are 0.4 10−3 (deg.−1) for natural rubber and ‐0.4.10−3 (deg.−1) for cis1,4 polybutadiene. This latter value is sharply contrasted with 0.4.10−3 (deg.−1) reported by CRESPI and FLISI who used the usual FLORY equation, but is consistent, at least in sign, with −1.3 · 10−3 (deg.−1) that has been deduced from recent viscosity data of ABE and FUJITA in a series of chemically similar theta solvents. However, one must wait until the molecular interpretation of the C1 term in the MOONEY‐RIVLIN equation becomes available, in order to know whether the temperature coefficient of <r2>0 calculated by the proposed method is physically meaningful.
The synthesis and properties of β‐vinylnylon 66
Authors: Baron Arthur L. , Marshall Richard A. 
Published: April 2003

AbstractThe homo‐ and copolymers of β‐vinylnylon 66 have been synthesized from β‐vinyladipic acid and hexamethylenediamine (and adipic acid). The cross‐linking reaction and chemical and physical properties of these polyamides are discussed.
Activation of poly[N‐(2‐hydroxypropyl)methacrylamide] for the binding of bioactive molecules, 1. Activation with 4‐nitrophenyl chloroformate
Authors: Lääne Ants , Haga Mati , Aaviksaar Aavo , Chytrý Vladimír , Kopeček Jindřich 
Published: April 2003

AbstractProper reaction conditions were determined for the activation of water‐soluble, biocompatible poly[N‐(2‐hydroxypropyl)methacrylamide] (1) by esterification with 4‐nitrophenyl chloroformate (2). The rate constants of hydrolysis and aminolysis of the 4‐nitrophenyl ester groups in resulting polymer 3 were compared. It was shown that at pH 8 – 9 the rate of aminolysis in water solutions is high enough for binding bioactive molecules via NH2 groups. Cobra venom acetylcholinesterase was bound to the activated polymer 3 and thermostability and immunogenicity of this product were studied.
Selective step‐growth phenol‐aldehyde polymerization, 2. Synthesis of 4‐tert‐butylphenol novolac resins and related open chain oligomeric compounds
Authors: Casiraghi Giovanni , Cornia Mara , Ricci Giovanni , Balduzzi Gianluigi , Casnati Giuseppe , Andreetti Giovanni Dario 
Published: April 2003

AbstractConstitutionally regular all‐ortho 4‐tert‐butylphenol‐formaldehyde novolac resins were prepared free from cyclic compounds, by reaction of bromomagnesium 4‐tert‐butylphenoxide in aprotic nonpolar media with paraformaldehyde. Short syntheses of dinuclear to decanuclear methylene‐linked chain oligomers were also achieved via bromomagnesium ion‐assisted reaction of suitable phenolic precursors with paraformaldehyde or 5‐tert‐butyl‐2‐hydroxybenzyl alcohol.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 12. Etude de la copolymérisation du méthacrylate de méthyle avec divers acrylates et méthacrylates. Détermination des microstructures
Authors: Brosse Jean‐Claude , Gauthier Jean‐Marie , Lenain Jean‐claude 
Published: April 2003

AbstractMethyl methacrylate was copolymerized with butyl or isobutyl acrylates, and butyl, isobutyl, or 2,3‐epoxypropyl methacrylates, by hydrogen peroxide, in the presence of ethanol under UV irradiation (at 254 nm) at room temperature. The analysis of the microstructures was based on resonance splitting of the methoxy protons of MMA, depending on their environment. This splitting was not obtained with isobutyl and 2,3‐epoxypropyl methacrylates. All the products were found to be predominantly syndiotactic.
Secondary structure of peptides, 11. How to synthesize helical poly(L‐phenylalanine)?
Authors: Kricheldorf Hans R. , Müller Detlef , Stulz Josef 
Published: April 2003

AbstractPolymerizations of L‐phenylalanine‐N‐carobxyanhydride(L‐Phe‐NCA) were conducted under various reaction conditions and the secondary structure of the resulting solid poly(L‐phenylalanine)s was examined by means of 50,3 or 75,4 MHz 13C NMR CP/MAS spectra. When primary alkylamines were used as initiators only α‐helix contents ≤ 60% were obtained regardless of solvent and temperature. However, a part of the β‐sheet structures was thermodynamically unstable and could be converted into α‐helices by reprecipitation. An α‐helix content > 90% was achieved only when weakly nucleophilic reagents, such as aromatic amines or water, were used as initiators in methylene chloride. A kinetic explanation of these results is discussed. Aprotic bases gave low yields of poly(L‐phenylalanine) and substantial amounts of low molecular weight side products. An α‐helix content ≥ 95%, was achieved when L‐Phe‐NCA was polymerized in pyridine at 100°C. The usefulness of IR spectra for the characterization of the secondary structure of poly(L‐phenylalanine) is discussed.
Active centre determination in ziegler‐natta polymerization. An examination of the allene inhibition method
Authors: Burfield David R. 
Published: April 2003

AbstractA study of the adsorption of allene on VCl3, TiCl3 Type 1.1, and TiCl3 Type H catalysts has been made. In the absence of cocatalyst, allene adsorption is observed and in the case of the TiCl3 Type 1.1 catalyst rapid oligomerization of allene occurs. Activation with Al(C2H5)3 leads to a slow consumption of allene with VCl3 and TiCl3 Type H, but shows no distinct change for the TiCl3 Type 1.1 catalyst. The amount of “adsorbed” allene is generally higher than the number of active sites and this is attributed to adsorption on sites which are inactive in polymerization and to consumption of allene through side‐reactions.
Properties of liquid crystalline polymers in solution, 1. Determination of the molecular weight of polymethacrylates with mesogenic sidegroups
Authors: Springer Jürgen , Weigelt Franz Werner 
Published: April 2003

AbstractDerivatives of poly(methacrylic acid) with mesogenic sidegroups are aggregated in solution. Through structural changes which also take place in the solid state, the fraction of the aggregates increases with storage time. The formation of aggregates depends on temperature and occurs relatively slowly. In solution, the degree of aggregation strongly depends on the solvent. This aggregation leads to relatively high tacticity in products obtained by radical initiated polymerisations.
Functional monomers and polymers, 106. Enantioface differentiation by using chiral polymers derived from (—)‐2‐exo‐hydroxy‐3‐bornanone
Authors: Liu Jui Hsiang , Kondo Koichi , Takemoto Kiichi 
Published: April 2003

AbstractChiral polymers containing 2,3‐exo‐dihydroxy‐3‐endo‐p‐tolyl‐3‐bornyl groups prepared by reaction of lithiated polystyrenes with (–)‐2‐exo‐hydroxy‐3‐bornanone (3), were treated with lithium aluminium hydride to yield products which can be used as reducing reagents. Asymmetric reductions of carbonyl compounds with LiAIH4 were carried out in the presence of both the chiral polymeric and 3‐endo‐p‐tolyl‐2,3‐exo‐bornanediol (4) as low molecular model compounds and the resulting enantiomeric excess was compared. The chiral polymers derived from 3 were found to be effective catalysts for the asymmetric reduction. The enantiomeric excess tends to increase with decreasing degree of crosslinking of the chiral polystyrene resins, exhibiting a high enantioselectivity in the case of chiral linear polystyrenes.
Miscibility in blends of polycarbonate and an aromatic polyester
Authors: Mondragon Iñaki , Cortazar Mila , Guzmán Gonzalo M. 
Published: April 2003

AbstractBlends of the polycarbonate of bisphenol‐A (PC) with polyacrylate (PA), an aromatic polyester formed from bisphenol A and terephthalic acid/isophthalic acid, were prepared by both melt and solution casting, and their transitional behaviour was examined by differential scanning calorimetry (DSC) and thermo‐optical analysis (TOA). Each blend composition was found to have a single glass transition temperature by DSC and by TOA. This result suggests that polycaronate and polyarylate form blends containing a single amorphous phase. Ester‐carbonate interchange reactions during melt‐mixing were experimentally found to be unimportant. Melting point depression was used to estimate the blend interaction parameter χ12.
Structural investigations on cellulose tricarbanilate: Conformation and liquid crystalline behaviour
Authors: Zugenmaier Peter , Vogt Ulrike 
Published: April 2003

AbstractThe phase behaviour of cellulose tricarbanilate (CTC) in ethyl methyl ketone (MEK) solutions was studied in the concentration range of 0,2 – 0,8 g/ml as a function of the temperature. By analyzing the textures in the polarizing microscope and by differential scanning calorimetry experiments several different phase transitions and mesophases were detected. At a concentration below 0,6 g/ml CTC in MEK, phase transitions were observed from the crystalline through a liquid crystalline (cholesteric) to the isotropic state. At concentrations higher than 0,6 g/ml, a different behaviour of the CTC solutions was detected and several transitions were found, but only the cholesteric‐isotropic transition could be identified. The concentration dependence of the cholesteric‐isotropic transitions was determined over the whole concentration range. The conformation of the CTC molecule was studied and a stiff, almost cylindrically shaped 3/2 helix with a repeat distance of 15,25 Å is proposed.
Cationic homopolymerization of 1,1′‐diisopropenylferrocene
Authors: Chishti Asif S. , Jablonski Chester R. 
Published: April 2003

Abstract1,1′‐Diisopropenylferrocene (1a) was homopolymerized using trifluoroacetic acid or boron trifluoride etherate as initiators, with excellent yields (>90%) of polymer (8100 < M̄n < 14700). Spectroscopic evidence established an initial protonation of 1a to give a tertiary monocarbenium ion (3) which does not readily undergo intramolecular cyclization (into 4). Analysis of isolated homopolymers by 1H and 13C NMR spectroscopy revealed significant residual unsaturation, consistent with facile chain transfer. Adventitious oxidation occurred during workup to give a mixed valence (Fe(II)/Fe(III)) polymer which could be distinguished spectroscopically from the unoxidized polymer.