Optimum spin-state selection for all multiplicities in the acquisition dimension of the HSQC experiment

SQ—SQ experiment for determination of relative signs of small nJ(29Si,13C) couplings in a wide variety of silicon compounds

“…For the pulse sequence applied on a (CH 3 ) 3 Si group, the silicon satellites in the carbon spectrum have an overall intensity given by natural abundance (4.7%) of 29 Si isotope which is about ten times enhanced by polarization transfer from the methyl hydrogens. [29] Then the signal intensity of 1 H- 29 Si-13 C isotopomer doublet can achieve almost 25% of the intensity due to 1 H- 28,30 Si- 13 C isotopomer in the carbon spectrum. Here, the second isotopomer may be excited by the SQ-SQ sequence.…”

“…Since the method should be applicable to quaternary carbons bearing no hydrogen atom (the other cases can be solved by the methods mentioned in the introduction section), 13 C-1 H couplings over two or more bonds must be employed. In the fragment O-C(α)H m -C(β)H n -C(γ )H o , numerous carbon-hydrogen couplings across different numbers of bonds are encountered.…”

“…[4] There are also more sophisticated methods like variants of E.COSY [5 -12] or TROSY [5,13 -23] producing similar type of results. They are usually used for detection of 1 H-Z coupling constants (Z frequently being 13 C or 15 N) and not for detection of signs of coupling constant between two low abundant nuclei.…”

“…Of the many 29 Si- 13 3 J(Si,C(β)) couplings may be detected using gHSQC-RELAY (P) or gHSQC-RELAY (D) pulse sequences [27] , but only under assumption that both C(α) and C(β) have directly attached hydrogen(s). If C(α) bears no hydrogen atom (m = 0), none of the silicon-carbon couplings can be detected by this method.…”

Time‐shared NMR experiments

“…11(A) is well suited to obtain spin-state selection in the detected F2 dimension using the very simple IPAP approach described in Ref. 24. Fully complementary in-phase (IP data: f 3 ¼ y and f 4 ¼ x) and antiphase (AP data: f 3 ¼ x and f 4 ¼ y) data are separately acquired without X-decoupling and further processed (IP 6 AP) to obtain the individual a-and b-spectra.…”