NMR, phosphorus

I mentioned this in my chapter in Annual Review. That was when I found the isotopic shift due to on the NMR phosphorus chemical shifts of ATP because I had come full circle. I was now showing an isotopic mass effect in a spectroscopic parameter and that s where I started in my graduate work. It isn t a very important finding, but it gave me great pleasure to discover yet another effect of isotopic mass of a stable isotope with a spectroscopic manifestation. 

NMR is a useful alternative to proton NMR. It is a reasonably sensitive nucleus which does not suffer from the relaxation problems associated with NMR. Phosphorus trichloride can be used as a reagent for self-recognition by a chiral substrate. Two molecules of an enantiomerically enriched alcohol react with each PCI3 molecule to form a phosphonate. Four stereochemically distinct species are possible (R,R) and (5, S) (a pair of enantiomers), (R,S) and (5, R) which are meso compounds. There are consequently three resonances in the 3ip NMR spectrum, whose non-equivalence is typically 0.5 ppm and integration gives results within 2% of those obtained by chiral GC methods. Subsequently methyl phosphoryl chloride has been employed in the same way giving improved chemical shift non-equivalences, A5 = 1 ppm (Scheme 3.3). 

NMR Proton nuclear magnetic resonance P-NMR Phosphorus-31 nuclear magnetic resonance DCB o-dichlorobenzene... 

It must be emphasized that NMR is first and foremost a tool for structural analysis and, in addition to the petroleum analyses described above, the technique (phosphorus NMR and sometimes nitrogen NMR) is abundantly used in all petrochemical synthesis operations. 

Quin L D and Verkade J G (eds) 1994 Phosphorus-31 NMR Spectral Properties in Compound Characterization and Structural Analysis (New York VCH)... 

IS the only phosphorus isotope present at natural abundance and has a nuclear spin of The H NMR spectrum of tnmethyl phosphite (CH30)3P exhibits a doublet for the methyl protons with a splitting of 12 Hz... 

Pyran-2-one, 5,6-dibromo-5,6-dihydro-reactions, 3, 735 Pyran-2-one, 5,6-dihydro-allylic bromination, 3, 799 dehydrogenation, 3, 724, 799 H NMR,3, 581 synthesis, 3, 841, 843 Pyran-2-one, 4,6-dimethyl-irradiation, 3, 677 photochemistry, 3, 678 Pyran-2-one, 5,6-dimethyl-chloromethylation, 3, 680 conformation, 3, 631 Pyran-2-one, 5-f ormyl-IR Spectra, 3, 595 Pyran-2-one, 6-formyl-IR spectra, 3, 595 Pyran-2-one, 5-halo-synthesis, 3, 799 Pyran-2-one, 3-hydroxy-IR spectra, 3, 595 Pyran-2-one, 4-hydroxy-methylation, 2, 57 3, 676 pyran-4-one synthesis from, 3, 816 reactions with phosphorus oxychloride, 2, 57 synthesis, 3, 792, 794, 795, 798 tautomerism, 2, 56 3, 642 Pyran-2-one, 4-hydroxy-6-methyl-methylation, 3, 692 reactions... 

NMR isotope measured. For example, for the detection of phosphorus by NMR in a sample containing 3 wt.% phosphorus, approximately 10 mg of sample are required. By contrast, the corresponding detection limit for Si in a similar situation is 22 dmes higher, due to the much lower natural abundance (4.7%) of the Si isotope. 

The primary function of this section is to organize data to faalitate NMR structure elucidation of organofluonne compounds Selectively fluonnated aliphatics are emphasized, whereas fluonnated aromatics are covered m less detail Inorganic nitrogen, phosphorus, silicon, and sulfur fluondes are not included, although compounds containing these and other heteroatoms attached to CF3 are the focus of multmuclear data presented later (see Table 16)... 

Phosphorus has only one stable isotope, J P, and accordingly (p. 17) its atomic weight is known with extreme accuracy, 30.973 762(4). Sixteen radioactive isotopes are known, of which P is by far the most important il is made on the multikilogram scale by the neutron irradiation of S(n,p) or P(n,y) in a nuclear reactor, and is a pure -emitter of half life 14.26 days, 1.7()9MeV, rntan 0.69MeV. It finds extensive use in tracer and mechanistic studies. The stable isotope has a nuclear spin quantum number of and this is much used in nmr spectroscopy. Chemical shifts and coupling constants can both be used diagnostically to determine structural information. 

Besides the thiocyanates, just mentioned, other 5-donor complexes which are of interest are the dialkyl sulfides, [MCl3(SR2)3], produced by the action of SR2 on ethanolic RhCl3 or on [IrClg] ". Phosphorus and arsenic compounds are obtained in similar fashion, and the best known are the yellow to orange complexes, [ML3X3], (M = Rh, Ir X = Cl, Br, I L = trialkyl or triaryl phosphine or arsine). These compounds may exist as either mer or fac isomers, and these are normally distinguished by their proton nmr spectra (a distinction previously made by the measurement of dipole moments). An especially... 

A seminal paper [155] examined platinum-phosphorus NMR coupling constants in a series of cis- and trans-platinum(II and IV) complexes. The trans-influence had hitherto been explained in terms of d7r-p7r bonding, in other words, such a mechanism dominated with trans-effect... 

The Ru(II)-BINAP complex,2 [Et2NH2]+[Ru2Cl5(BINAP)2]-,3 is prepared as a toluene solvate in nearly pure form by this procedure. Typical crystallized product shows no other signals in the phosphorus NMR and gives a good combustion analysis. The material is quite stable and can be routinely handled in air. Storage under nitrogen will extend its shelf life, however. 

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