Singlet-triplet coupling constant

As for CIDNP, the polarization pattern is multiplet (E/A or A/E) for each radical if Ag is smaller than the hyperfme coupling constants. In the case where Ag is large compared with the hyperfmes, net polarization (one radical A and the other E or vice versa) is observed. A set of mles similar to those for CIDNP have been developed for both multiplet and net RPM in CIDEP (equation (B1.16.8) and equation (B1.16.9)) [36]. In both expressions, p is postitive for triplet precursors and negative for singlet precursors. J is always negative for neutral RPs, but there is evidence for positive J values in radical ion reactions [37]. In equation (B 1.16.8),... 

Singlet. Doublet. Triplet. Shifts in p.p.m. from external TFA + upheld from TFA. Coupling constants in Hertz. Basic quartet, C1F5 group CF, 6.76, multiplet CFj, 38.4, J TF = 3.3, septet. Triplet. 4 of 10 lines. Pentet. Septet. Quartet. 6 of 8 lines. 7 of 9 lines. Septet. Quartet. Triplet. 5 of 7 lines. Sextet. " Pentet. 6 of 8 lines. Pentet. Quartet. Pentet. Sextet. Sextet. Doublet. 5 of 7 lines. " Pentet. Pentet. Quartet. Pentet. Quartet. Triplet. Triplet. Triplet. 

Singlet. Doublet. Triplet." Chemicalshiftsinp.p.m. + downfield from external MciSi. Coupling constants in Hertz. " OH (2.43), singlet. 

Organic compounds contain four types of carbon atom methyl, methylene, methine and quaternary. And so if we simply record the spectrum as we would a proton spectrum, the result will be a series of quartets, triplets, doublets and singlets, each associated with a carbon-proton one-bond coupling constant of between 125 and 250 Hz. If we are dealing with a complex molecule, these multiplets will overlap and give us spectra which are almost impossible to analyse. In addition, coupling interactions over two or more bonds complicate the picture still further. 

Note The peaks listed are singlets, unless described as doublets (d), triplets (t), quartets (q), or multiplets (m). Coupling constants (in Hz) are given in parentheses. 

In ruthenocene it also proved possible at 77 K to resolve the broad band containing the 12+ -> 1n, and 1Z+ -+ x4> transitions, but as for Fe(Cp)2 only one spin-forbidden d-d band, assigned as shown in Table 11, could be found, despite a spin-orbit coupling constant of the order of 1 kK. Note that although the 3I1 (on S4), 34 (o2 tr 5 3), and 3II (o2 n 6 3) levels are predicted (81) to be split by , %, and 31, respectively, abnormally large band widths would not be anticipated since only one component of each triplet level is capable of mixing with the nearby singlet states. 

NMR spectra were recorded on Bruker AC200 spectrometers unless indicated otherwise deuteriated chloroform was used as solvent and tetramethylsi-lane as internal reference. Chemical shifts (8) are given in ppm. The following abbreviations were used to define the multiplicities s, singlet d, doublet t, triplet q, quartet m, multiplet br, broad coupling constants (/) are measured in Hertz (Hz). IR spectra were recorded on a Nicolet Magna-550 FTIR... 

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