- Photochemically reactive polymers; The synthesis and photochemistry of amide polymers and model compounds containing metal-metal bonds and internal radical traps
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The synthesis and photochemistry of a photochemically reactive polymer that has internal metal-radical traps (chlorine atoms) along its backbone is reported. Reaction of the organometallic 'diamine' (CpCH2CH2NH2)2Mo 2(CO)6 with an activated mixed anhydride derivative of 3,4-dichlorohexanedioic acid gave the polymer [-CHClCH2C(O)NHCH2CH2(η5-C 5H4)(CO)3Mo-Mo(CO)3(η 5-C5H4)CH2CH2NHCOCH 2CHCl-]n. The difunctional activated mixed anhydride was used because the Mo-Mo bond reacts with acyl chlorides to form oligomeric amides containing -Mo(CO)3Cl units. As an aid to the spectroscopic characterization of the polymers, model complexes were synthesized by reacting (CpCH2CH2NH2)2Mo 2(CO)6 with activated mixed anhydrides of chloroacetic acid and 5-chlorovaleric acid. Thus, (η5-C5H4R)2Mo 2(CO)6 (R=-CH2CH2NHCOCH2Cl and -CH2CH2NHCO(CH2)3CH2Cl) were synthesized by reacting (CpCH2CH2NH2)2Mo 2(CO)6 with CH3CH2OC(O)OC(O)CH2Cl and CH3CH2OC(O)OC(O)(CH2)3CH 2Cl, respectively. Because of the metal-metal bonds along the backbone, the polyamide is photochemically reactive (as are the model complexes), undergoing metal-metal bond photolysis reactions similar to the Cp2Mo2(CO)6 dimer. The products contain CpMo(CO)3Cl units, indicative of 'self-trapping' by the chlorine atoms built into the polymer and model complexes. Photochemical decomposition also occurred in the solid state without external metal-radical traps.
- Nieckarz, Gregory F.,Litty, John J.,Tyler, David R.
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