3,4-Difluorothiophene

    Parameter     ppm  Hz

      D(A)         6.507
      D(X)        23.797
       J(A,A')         3.94
       J(A,X)          1.23
       J(A,X')         3.17
       J(A',X)         3.17
       J(A',X')        1.23
       J(X,X')       -12.88
     
     CHRISTIANSEN,H. ET AL. ARK.KEMI. 30, 561 (1968)
     F-19 REFERENCE:HEXAFLUOROBENZENE.