Comparison of sp-C–H···N Hydrogen Bond Lengths in Fluorinated and Nonfluorinated Ethynylbenzenes

Abstract

1,4-Diethynyltetrafluorobenzene was prepared and separately co-crystalized with 4,4′-bipyridine, 1,2-bis(4′-pyridyl)ethyne and trans-1,2-bis(4′-pyridyl)ethane to form 1:1 co-crystals that each contain essentially linear C–H···N hydrogen bonded ribbons of alternating diyne and dipyridine. The C–H···N hydrogen bond distances and angles in the 1:1 co-crystals are analyzed and compared to the previously reported C–H···N hydrogen bond distances and angles in the corresponding co-crystals formed with 1,4-diethynylbenzene. 1,4-Diethynyltetrafluorobenzene was prepared and separately co-crystalized with 4,4′-bipyridine, 1,2-bis(4′-pyridyl)ethyne and trans-1,2-bis(4′-pyridyl)ethane to form 1:1 co-crystals that each contain essentially linear C–H···N hydrogen bonded ribbons of alternating diyne and dipyridine. The C–H···N hydrogen bond distances and angles in the 1:1 co-crystals are analyzed and compared to the previously reported C–H···N hydrogen bond distances and angles in the corresponding co-crystals formed with 1,4-diethynylbenzene.