Phosphorus decoupling

Decoupled Spectrum Proton Decoupling> Proton and Phosphorus Decoupling... 

There are two main classes di-Os(PRi )4H2 and Os(PR3)3H2Cl2 (Scheme 12 and Table 17). The cis configuration of the former is established, in the case of Os(PMePh2)4H2 at least, by phosphorus decoupling NMR experiments 276 the high-field NNMR spectra of Os(PMePh2)2H2Cl2 and of... 

Figure 4.12. Simplification of the conventional proton spectrum (a) of the palladium phosphine 4.4 in CDCI3 by the application of broadband phosphorus decoupling (b). All long-range couplings are removed, as is most apparent for the alkene proton (7.2 ppm) and the ortho protons of the phenyl rings (above 7.8 ppm).

Compound 1 contains one phosphorus atom, so that the broad-band proton decoupled spectrum is extremely simple it consists of only one line at 8.5 ppm. This spectrum is shown in Fig. 22, together with the proton-coupled spectrum. 

Fig. 22a,b Phosphorus-31 spectra of compound 1. a Protons decoupled b proton-phosphorus coupling present... 

It is by no means unusual to come across compounds which contain more than one phosphorus atom Fig. 23 shows the proton decoupled coupled phosphorus spectrum of compound 6, which contains three chemically different phosphorus nuclei. Phosphorus behaves in NMR just like the proton, so we shall expect to see three signals, split into multiplets if there is an observable coupling between the phosphorus nuclei. 

Figure 29 shows the P,C correlation for compound 1 carried out by selecting a J value of 15 Hz. The decoupled phosphorus signal is shown at the top, the proton decoupled carbon-13 spectrum on the left. The actual 2D spectrum... 

The first thing that we can see is that the 2D spectrum is not decoupled with respect to the phosphorus the methine carbon C-P doublet in the 13C spectrum is associated with a doublet along the phosphorus axis, from which can of course be extracted. 

The structure of the two rhodium-acyl complexes was elucidated using COSY90 spectra, selective decoupling of the phosphorus resonances, and HMQC spectra. Spectrum 3d (Figure 6.13) shows the complete simulation of the NMR spectrum obtained at 223 K. The NMR spectrum... 

Treatment of [Hf(BH4)3 N(SiMe2CH2PMe2)2 ] with Lewis bases (NEt3 or PMe3) yields the dinuclear trihydride [ Hf[N(SiMe2CH2PMe2)2] 2(H)3(BH4)3]. This complex is fiuxional JH and selectively decoupled 31P NMR spectra show the presence of three equivalent hydrides coupled to four equivalent phosphorus nuclei.140... 

It is possible to distinguish between phosphine complexes of platinum and rhodium by phosphorus-31 NMR spectroscopy, a technique not available to the early coordination chemists. Given that phosphorus-31 (100% abundant), platinum-195 (33% abundant), and rhodium-103 (100% abundant) all have nuclear spin quantum numbers of 1/2, sketch 31P NMR spectra of the following complexes (assume all protons are decoupled from the phosphorus nuclei) ... 

C-5 of the ribofuranose residue can easily be assigned. Another rule is found for the anomeric carbons C-l of the ribofuranose residue which always absorb at lowest field [696]. C-4 can be assigned by noting the phosphorus-carbon long-range coupling in the proton broadband-decoupled 13C NMR spectra of nucleotides [750] as demonstrated in Fig. 5.9. 

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