Structural Characterization of a Cyclohexameric meta-Phenyleneethynylene Made by Alkyne Metathesis with In Situ Catalysts U.H.F.B. and P.-H.G. thank the National Science Foundation (CHE 9814118), the Research Corporation, and the EPSCoR Office of the State of South Carolina for generous support. R.D.A. thanks the Alexander von Humboldt Foundation for an award which supported this work.