Positive spectrum polymer

Plutonium(IV) polymer has been examined by infrared spectroscopy (26). One of the prominent features in the infrared spectrum of the polymer is an intense band in the OH stretching region at 3400 cm 1. Upon deuteration, this band shifts to 2400 cm 1. However, it could not be positively assigned to OH vibrations in the polymer due to absorption of water by the KBr pellet. In view of the broad band observed in this same region for I, it now seems likely that the bands observed previously for Pu(IV) polymer are actually due to OH in the polymer. Indeed, we have observed a similar shift in the sharp absorption of U(0H)2S0ir upon deuteration (28). This absorption shifts from 3500 cm 1 to 2600 cm 1. 

ADMET reaction. The 13C NMR spectrum also allows the scientist to distinguish between cis and trans internal sp2 carbons as well as the allylic carbons, which are adjacent to the internal vinyl position. Using quantitative 13C NMR analysis, the integration of the peak intensities between die allylic carbon resonances and diose of the internal vinyl carbons gives die percentage of trans/cis stereochemistry diat is present for the polymer.22 Empirically, the ratio of trans to cis linkages in ADMET polymers has typically been found to be 80 20. Elemental analysis results of polymers produced via ADMET demonstrate excellent agreement between experimental and theoretical values. 

Hunter (60) reported a self-assembled open polymer formed by a zinc porphyrin bearing one para-aniline substituent at the meso position. The ortho- and mela-analogs discussed above form closed dimers, but the geometry of the para-derivative precludes this, and polymerization is the only alternative (76, Fig. 31). Although the dilution experiments could be fitted to a non-cooperative polymerization model with a pairwise association constant (K = 190 M 1) practically identical to that found for simple aniline-zinc porphyrin complexes (K = 130 M 1), broadening of the 4H NMR spectrum at high concentrations is characteristic of oligomerization. 

In donating solvents the subtle effects determining the chemical shift in chloroform, benzene, and hexane are apparently masked. In hexane, which is considered a poor solvent, self-association is possible and would explain the appearance of the Sn spectrum. Chloroform and benzene are excellent solvents for organometallic polymers, and the structure and downfield position support a well-solvated, unassociated environment. 

The 13C-NMR spectrum of the 5-methylhexadiene polymer in CDCI3 solution is given in Figure 4. The spectrum (six peaks) is consistent with the structure of a polymer resulting from a regular head-to-tail 1,2-polymerization. The peak at 33.31 ppm consists of two overlapped peaks. These are attributed to the methylene carbons adjacent to the double bond and to the backbone methine carbon these two peaks are in the same position by coincidence. 

The number of turnovers (10) in hydrocarbon production without apparent decrease in activity proved that the reaction was indeed catalytic. The IR spectrum of the recovered resin showed small absorptions due to CpCo(C0)2 5 due to some recar bony la-tion of " CpCo". In addition, a broad distinct band at 1887 cm"l was seen. The identity of the species exhibiting this carbonyl band is still a mystery in particular, the band position does not match that reported for any of the CpCo (CO) 2 -derived di- and trinuclear carbonyls (vide supra). It is tempting to associate this band with seme catalytic intermediate, such as the polymer-bound analogues of CpCo(H)2(C0) and CpCo(HKPh)(CO), but this is pure speculation. 

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