1,1-Dibromo-3-fluoro-1,3-butadiene

    Parameter     ppm  Hz

      D(A)         4.902
      D(B)         4.806
      D(C)         6.888
       J(A,B)         -3.22
       J(A,C)          0.54
       J(A,X)         16.08
       J(B,C)         -0.31
       J(B,X)         46.30
       J(C,X)         17.33
     
     BOTHNER-BY,A.A. & KOSTER,D.F. J.AM.CHEM.SOC. 90, 2351 (1968)