An einen Zirkel erinnert die Struktur des planaren, annähernd C2v‐symmetrischen Moleküls Se2NCl3 1. Dieses Chloridnitrid ist leicht löslich, stabil und zugleich sehr reaktiv. Das verbrückende Chloratom in 1 läßt sich leicht mit GaCl3, unter Bildung von [Se2NCl2]‐[GaCl4] herauslösen, dessen Kation eine U‐förmige Struktur hat. Beide Verbindungen liegen im diamagnetischen Singulett‐Grund‐zustand vor.
proline residues. The L-proline' multiplet can be separated easily by a transfer from pcis to /3"""s as shown in Figure 6 b.In order to excite only the pis proton of L-proline', magnetization was transferred from the strongly coupled pair p + 6"""" to the strongly coupled pair pcis + fra's. The resulting multiplet is represented in Figure 6 c and corresponds perfectly to the pattern in Figure 6a obtained by soft-COSY. I Qa 7 I Fig. 6. a) Multiplets obtained with normal soft-COSY of 1, centered at 6 = 1.60 in o, and b = 4.28 in wz.To the left, cross-peak correlating the p"""' proton (at 6 = 1.62) and the a proton (6 = 4.32) of L-proline*; to the right, cross-peak connecting the P" proton (6 = 1.58) and the a proton (6 = 4.23) of L-proline'. b) SPLIT-COSY multiplet of L-proline' alone obtained by injection of magnetization from P's (6 = 2.10) to B"""" via J(p"B""") = -12.8 Hz with T~, =78 ms. c) SPLIT-COSY multiplet of L-proline' alone obtained by injection of magnetization from the two nearly degenerate protons 6"' (6 = 3.52) and bL""" (6 = 3.57), with J(bCis6"""") = -11.7 Hz, to the two nearly degenerate and strongly coupled protons Y'""~ and (6 =1.61 and 1.58, with J(y''""'p"") = 3.4 Hz) via J(6c'y"'ns) = 3.1 Hz and J(6tr~"sy"""s) = 6.7 Hz. The cleanest in-phase magnetization was obtained for T~~, = 220 ms. In this case, the double irradiation period was followed by a hard purging pulse in order to remove antiphase terms [6]. Experimental conditions were the same as those for the spectra in Figure 3.Our new SPLIT-COSY technique allows one to separate overlapping multiplets in crowded parts of COSY spectra in order to extract hidden information. The structure of the resulting multiplets is the same as in soft-COSY, unlike the multiplets obtained in Selectively Znverted Soft COSY (SIS-COSY).r'51 In general, samples containing mixtures of isomers, which are likely to give overlapping cross-peaks, should become amenable to investigation, provided each isomer has at least one site with a distinct chemical shift. If necessary, several consecutive HOHAHA transfer steps may be used.
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