Long-range "C,H NMR coupling coastants were measured in Strychnine at 400 MHz by a method that employs selective excitation of individual 13C sites under decoupled conditions followed by polarization traosfer to protolls. The sensitivity was improved by performing eight simultaneous soft-pulse experiments coded ( f) according to a Hadamard matrix and later separated by reference to the same matrix. The antiphase "C,H splittings were measured by Jdoubling performed in the frequency domain.

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Mixtures of isomers of (perfluoroalkyl)tetramethylcyclopenta-1,3-dienes (CH 3 ) 4 C 5 H(CF 2 ) n CF 3 (n = 3, 5, 7, 9) were synthesized as precursors of new cyclopentadienyl ligands for organotransition metal catalysis in fluorous biphase media and characterized by combination of GC-MS and 13 C NMR spectroscopy. Rhodium(III) chloro complexes [Rh{(CH 3 ) 4 C 5 (CF 2 ) n CF 3 }Cl 2 ] 2 and rhodium(I) carbonyl complexes [Rh{(CH 3 ) 4 C 5 (CF 2 ) n CF 3 }(CO) 2 ] were prepared from the cyclopentadienes and molecular structure of [Rh{(CH 3 ) 4 C 5 (CF 2 ) 5 CF 3 }Cl 2 ] 2 was determined by X-ray diffraction. The ligands are electronically close to the unsubstituted cyclopentadienyl as shown by values of carbonyl stretching frequencies in the carbonyl complexes. Neither carbonyl frequencies nor NMR chemical shifts of the complexes are substantially affected by the length of the perfluoroalkyl chain.Catalysis in fluorous biphase systems (FBS), a method of catalyst separation alternative to catalyst heterogenization 1,2 or other biphase systems 3,4 , has gained considerable attention since the first report by Horváth and Rábai 5 in 1994. The interest in the topic, recently reviewed 6-8 , continues to grow. Although the majority of work still concentrates on solubilization of phosphine ligands, including the pioneering work of Horváth and Rábai, the range of available fluorophilic ligands broadens. It is somewhat surprising that research on solubilization of cyclopentadienyl ligands laggs behind

Two pulse sequences applicable to the determination of relative signs of coupling constants, gHSQC-RELAY(P) and gHSQC-RELAY(D), were developed and tested. These sequences are suitable for determination of relative signs of long-range coupling constants (<2 Hz) between two heteronuclei of low abundance (such as (29)Si and (13)C), and are applicable even to cases in which one of the heteronuclei ((29)Si) does not exhibit coupling with some of the detected protons ((1)H). The two sequences differ in the manner in which they suppress undesirable homonuclear coherence transfers. Each of the sequences can be combined with an isotope filter for better suppression of the centerlines arising from more abundant NMR-inactive isotopes. The sequences were tested on ethoxytrimethylsilane and (E)-(buta-1,3-dienyloxy)trimethylsilane, and we conclude that (2)J((29)Si-O-(13)C) is positive while (3)J((29)Si-O-C-(13)C) is negative in both compounds.