cyclobutene

    Parameter     ppm  Hz

      D(A)         5.95
      D(B)         2.57
       J(A,A')         2.70
       J(A,B)         -0.80
       J(A,B')        -0.80
       J(A,B'')        1.55
       J(A,B''')       1.55
       J(A',B)         1.55
       J(A',B')        1.55
       J(A',B'')      -0.80
       J(A',B''')     -0.80
       J(B,B')       -12.00
       J(B,B'')        1.65
       J(B,B''')       4.35
       J(B',B'')       4.35
       J(B',B''')      1.65
       J(B'',B''')
                     -12.00
     
     BORCIC,S. & ROBERTS,J.D. J.AM.CHEM.SOC. 87, 1056 (1965)
     J(C-13,A):170HZ, J(C-13,B) & J(C-13,B'):140HZ.