Conducting organometallic polymers are an interesting class of materials because they combine the electronic properties of metals with the simpler processing requirements of organic polymers. In an approach to incorporating poly(thiophene) segments into controlled three-dimensional environments, we have synthesized 5,5′-bis(diphenylphosphino)-2,2′bithiophene, Ph 2 P(C 4 H 2 S) 2 PPh 2 , and have reacted this ligand with Mo(CO) 4 (nbd) in a 1:1 ratio. The product of this reaction is a cyclic oligomer, as indicated by the presence of only cis-Mo(CO) 4 absorptions in the IR spectrum and the absence of resonances of free phosphines in the 31 P{ 1 H} NMR spectrum. Size exclusion chromatography of the polymer in THF gives an M h n value of 6.0 × 10 3 and M h w value of 9.7 × 10 3 for the polymer. To better understand the structural features of the polymer, model complexes for the edge, Mo(CO) 5 (Ph 2 P(C 4 H 2 S) 2 -PPh 2 )Mo(CO) 5 , and the corner, cis-Mo(CO) 4 (Ph 2 P(C 4 H 2 S) 2 H) 2 and cis-Mo(CO) 4 (Ph 2 PC 4 H 2 S)H) 2 , of the cyclic polymer have been prepared and characterized. X-ray crystal structures of Ph 2 P-(C 4 H 2 S) 2 PPh 2 and the edge model have also been determined.
Polythiophenes exhibit interesting third-order nonlinear optical properties but poor solubilities. Incorporating polythiophenes into transition metal complexes should yield readily soluble materials, and the transition metal substituent may alter third-order nonlinear optical properties of the polythiophene. In this paper, we report the synthesis and characterization of 2-diphenylphosphinothianaphthene, A, and its trans-PdCl 2 L 2 , B, and cis-PtCl 2 L 2 , C, analogues. Additionally 2-diphenylphoshino-5:2′,5′:2′′-terthiophene, D, its trans-PdCl 2 L 2 complex, E, both first prepared by Wolf, 25 the previously unprepared cis-PtCl 2 L 2 analogue, F, and the oxide of A, G, were prepared and investigated for nonlinear optical (NLO) behavior. No appreciable third-order NLO behavior was observed for A, D, or G. However both E and F exhibited nonlinear refraction, as shown by Z-scan measurements, and nonlinear absorption. The nonlinear absorption was significantly stronger for E, indicating that the metal center has a significant affect on nonlinear absorption. This is the first reported observation of this type of nonlinear behavior in metalphosphinothiophene systems.
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