Applications of P-31 NMR to the Study of Metal-Phosphorus Bonding (original) (raw)
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Inorganic Chemistry, 1992
Two-dimensional homonuclear shift correlated spectroscopy (COSY) is applied to the analysis of a series of dinuclear R(1) complexes containing phosphine ligands. On the basis of the spectra of known symmetrical dimers, it is established that cross-peak positions of the Pt-P satellite signals can be used to determine the sign and magnitude of the 2JR_p coupling constant. This coupling constant has been correlated with the strength of the Pt-Pt interaction in these complexes. Using cross-peak positions present in the spectra of unsymmetrical dimers which contain five or more phosphorus nuclei, previously unobtainable values for the 2Jpt-p coupling constants are determined. The signs and the magnitudes of these coupling constants are found to follow the trans effect trend established for ligands in other Pt complexes.
Inorganic Chemistry, 1992
Two-dimensional homonuclear shift correlated spectroscopy (COSY) is applied to the analysis of a series of dinuclear R(1) complexes containing phosphine ligands. On the basis of the spectra of known symmetrical dimers, it is established that cross-peak positions of the Pt-P satellite signals can be used to determine the sign and magnitude of the 2JR_p coupling constant. This coupling constant has been correlated with the strength of the Pt-Pt interaction in these complexes. Using cross-peak positions present in the spectra of unsymmetrical dimers which contain five or more phosphorus nuclei, previously unobtainable values for the 2Jpt-p coupling constants are determined. The signs and the magnitudes of these coupling constants are found to follow the trans effect trend established for ligands in other Pt complexes.
Inorganic Chemistry, 1992
The synthesis and characterization of a new platinum(1) phosphine complex, [Pt,(p-dppm)(q'-dppm)dppeCl]Cl, is reported. This unique complex is the fmt example of a stable Pt(1) dimer in which all three types of coordination possible for a diphosphine ligand are observed. To structurally characterize this complex, we have employed one-and two-dimensional 31P NMR spectroscopy. Using 14 other structurally simpler platinum phosphine complexes, it is established that the 31P homonuclear shift correlated spectroscopy (COSY) technique provides valuable information about both the phosphorus-phosphorus and platinum-phosphorus couplings, especially when the rtSOnanceS in the onedimensional spectra are poorly resolved. The ,JRP and 3JR-p coupling constants are obtained from the relative positions of the observed cross-correlations with respect to the main phosphorus resonances. From the analysis of the coupling patterns observed and the coupling constants measured from the two-dimensional data sets, determination of the geometrical arrangement of the phosphine ligands is demonstrated. The structural assignment of the new Pt complex is based on the analysis of its ,IP COSY map and further supported by the COSY studies of the other platinum complexes.
High resolution 31P solid state NMR in phosphorus-transition metal compounds
Materials Chemistry and Physics, 1991
The use of a high resolution solid state 31P NMR technique to investigate the coordination of phopshorus ligands bound to transition metal atoms is reviewed using examples which include information on molecular structure and crystallographic sites in organometallic solids, and characterization of supported transition metal complexes on surfaces. Moreover 31P CPMAS (cross polarization magic angle spinning) experiments can afford a wealth of information such as chemical shift anisotropy, isotropic coupling constants with quadrupolar nuclei and quadrupole coupling constants that are often obscured in solution state due to the rapid isotropic motion of the molecules.
Journal of the American Chemical Society, 1990
The nature of the carbon-phosphorus double bond in ~,~,~-~-B L I , C~H~P = C (S~M~~)~ and the carbon-phosphorus triple bond in 2,4,6-t-Bu3C6H2C=p has been studied by 13C and 31P solid-state NMR. Magic angle spinning and static cross-polarization experiments have been used to determine the principal elements of the I3C and 31P shielding tensors. In the I3C spectra, the presence of a dipolar coupling to the IIP nucleus permits assignment of the orientation of the I3C shielding tensors in the molecular frame. These shift tensors are compared to previous work on diphosphenes, disilenes, alkenes, and alkynes. It is found that the shift anisotropies for 3'P and I3C in these multiply bonded environments are quite similar when the larger intrinsic chemical shift range for 31P is taken into account.
Journal of Organometallic Chemistry
A crystal and molecular structure determination of [Pt(PPh3)2(2,4,6-mesitylNSO)] shows a side-on coordination via the NS unit to Pt0, while the mesityl group is in the cis configuration with respect to SO. The same structure persists in solution, as shown by IR, UV, 1H-, 31P- and 195Pt-NMR studies on [Pt(PPh3)2(RNSO)] (R = Ph, 4-tol, 2-tol, 3,5-xylyl and 2,4,6-mesityl). In the case of [Pt(PPh3)2(Ph15NSO)], 31P- and 195Pt-NMR gave the cis and trans-couplings 2J(31PPt15N), 1J(31P195Pt) and 1J(195Pt15N). The PPh3 groups interchange their positions intramolecularly, probably via a rotation about the Pt(NS) axis. From the isotopic shifts (15N) in the vibrational spectra of both the free and coordinated PhNSO it is concluded that there is hardly any coupling between ν(SO) and ν(NS).In the light of these conclusions, the unstable [Pt(PPh3)2(RNSNR)] complexes, for which N-coordination has been tentatively proposed on the basis of the IR and UV spectra, were reinvestigated. It may ...