Synthesis and Characterization of Cyclic Oligomeric [<i>cis</i>-Mo(CO)₄(Ph₂P(C₄H₂S)₂PPh₂)]<i>_n</i> and Model Complexes for the Edge and Corners in the Cyclic Oligomer

Abstract

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 M̄ n value of 6.0 × 10 3 and M̄ 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.