PHOTOCHEMICALLY REACTIVE POLYMERS - SYNTHESIS, CHARACTERIZATION, AND PHOTOCHEMISTRY OF A POLYUREA CONTAINING A CP2MO2(CO)6 MOLECULE ALONG THE POLYMER BACKBONE AND OF POLY(ETHER URETHANE) COPOLYMERS WITH CP2MO2(CO)6 AND CP2FE2(CO)4 MOLECULES ALONG THE POLYMER BACKBONE

The synthesis of an oligomeric urea containing Mo-Mo bonds along the backbone is reported. Reaction of the organometallic "diamine" [(eta(5)-C5H4CH2CH2NH3+)2Mo2(CO)6][NO3-]2 with OCN(CH2)6NCO (hexamethylene diisocyanate, HMDI) in an interfacial synthesis gave [-NHCH2CH2C5H4(CO)3Mo-Mo(CO)3C5H4CH2CH2NHC(O)NH(CH2)6NHC(O)-]n. Similarly, poly(ether urethane) copolymers containing Mo-Mo or Fe-Fe bonds along the backbone were synthesized by reacting (eta(5)-C5H4CH2CH2OH)2Mo2(CO)6 or (eta(5)-C5H4CH2CH2OH)2Fe(CO)4 with Hypol 2000, a commercially available polyether capped with toluene diisocyanate end-groups. The polymers and oligomers were characterized by elemental analysis, by infrared, H-1 NMR, and electronic absorption spectroscopy, and by molecular weight. As an aid to the spectroscopic characterization of the polyurea, a model complex was synthesized by reacting CH3(CH2)5NCO with [(eta(5)-C5H4CH2CH2NH3+)2Mo2(CO)6][NO3-]2. Because of the metal-metal bonds along the backbones, the polymers and oligomers are photochemically reactive, undergoing metal-metal-bond photolysis reactions similar to the Cp2Mo2(CO)6 and Cp2Fe2(CO)4 dimers. Irradiation leads to homolysis of the metal-metal bonds, as evidenced by formation of Cl(CO)3MoC5H4-R-C5H4Mo(CO)3Cl or Cl(CO)2FeC5H4-R-C5H4Fe(CO)2Cl type products when the polymers are irradiated in the presence of CCl4. In the presence of triethyl phosphite, disproportionation of the Mo-Mo- and Fe-Fe-bonded units occurred to give polymer fragmentation products containing (C5H4R)Mo(CO)3- and (C5H4R)Mo(CO)2(P(OEt)3)2+ or (C5H4R)Fe(CO)2- and (C5H4R)Fe(CO)(P(OEt)3)2+ groups, respectively. Photochemical decomposition of the poly(ether urethanes) also occurred over several days in the solid state. Both light and oxygen are necessary for this decomposition in the solid state. It is proposed that cleavage of the metal-metal bonds leads to polymer fragmentation and the formation of metal oxide species in this solid-state reaction.