Measurement of 195Pt chemical shift anisotropy in two solid Pt complexes, [Me3Pt(acetylacetonato)]2 and [Me3Pt]2SO4.4H2O. Effect on solution-state spin relaxation

Doddrell, David M.; Barron, Peter F.; Clegg, Donald E.; Bowie, Carol

doi:10.1039/c39820000575

Cited by 20 publications

(8 citation statements)

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“…On progressive cooling, the β-CF 2 resonance separates into two doublets corresponding to two diastereotopic fluorines, and two broad humps begin to appear, corresponding to two diastereotopic α-CF 2 fluorines. At −60 °C these become two sharp doublets, well separated by 29.8 ppm (at 470 MHz), but with platinum satellites still too broad to observe, probably due to chemical shift anisotropy effects that have been well documented in other compounds. − When the sample of 14 is heated to 90 °C, the β-CF 2 fluorines are observed as a sharp singlet with platinum satellites and the α-CF 2 has also begun to sharpen to a singlet.…”

Section: Resultsmentioning

confidence: 98%

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

et al. 2001

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Reaction of (TMEDA)Pt(CH 3 ) 2 with n-perfluoropropyl iodide in hexanes results in an apparent cis addition of the perfluoroalkyl iodide to give the six-coordinate Pt(IV) complex (TMEDA)Pt(n-C 3 F 7 )(CH 3 ) 2 I (6a). Complex 6a slowly and reversibly reductively eliminates CH 3 I in solution to afford an equilibrium with the Pt(II) complex (TMEDA)Pt(n-C 3 F 7 )(CH 3 ) (9a). Addition of triethylamine drives the equilibrium toward 9a. Identical reactions of perfluoroethyl iodide are observed to afford 6b and 9b. Reaction of 6a with AgBF 4 generates the cationic Pt(IV) complex [(TMEDA)Pt(n-C 3 F 7 )(CH 3 ) 2 (OH 2 )]BF 4 (11), which reacts with NaCl to form (TMEDA)Pt(n-C 3 F 7 )(CH 3 ) 2 Cl (12); both reactions retain the cis stereochemistry of the starting material 6a. Reaction of 9a with CF 3 SO 3 H in moist solvents generates the cationic Pt(II) complex [(TMEDA)Pt(n-C 3 F 7 )(OH 2 )]O 3 SCF 3 (17), which reacts with iodide to afford the neutral iodide complex (TMEDA)Pt(n-C 3 F 7 )I ( 14). Reaction of complex 9a with I 2 in hexanes results in trans addition of I 2 to generate (TMEDA)Pt(C 3 F 7 )(CH 3 )I 2 (13), which is converted to (TMEDA)Pt(n-C 3 F 7 )I ( 7) by treatment with AgBF 4 followed by NaI. Complex 14 reacts with NaBH 4 to produce (TMEDA)Pt(n-C 3 F 7 )H ( 18). The TMEDA ligand can be displaced from 9a by DPPE to give (DPPE)Pt(n-C 3 F 7 )(CH 3 ) ( 19), which reacts with CF 3 -SO 3 H to give the triflate complex (DPPE)Pt(n-C 3 F 7 )O 3 SCF 3 (20), in equilibrium with a water complex, [(DPPE)Pt(n-C 3 F 7 )(OH 2 )]O 3 SCF 3 (21). Reaction of 20 with iodide, or 19 with I 2 , gives (DPPE)Pt(n-C 3 F 7 )I ( 22), which can be converted to the hydrido complex (DPPE)Pt(n-C 3 F 7 )H ( 23) with NaBH 4 . The X-ray crystal structures of complexes 6a, 9a, 9b, 10, 13, 18, 19, 20, and 23 have been determined, and structural comparisons in terms of ligand cis and trans influences are discussed.

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Section: Resultsmentioning

confidence: 98%

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

et al. 2001

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“…If the CSA mechanism is the dominant relaxation mechanism, the rate of spin−lattice relaxation, ( T 1 ) -1 , depends on the square of the CSA and the square of the applied magnetic field, B 0 , thus providing a good estimate of the CSA − The first solid-state 195 Pt NMR experiments (apart from single-crystal experiments) , were undertaken on compounds having relatively high symmetry with therefore relatively small CSAs (<1000 ppm). ,,,,− Such species were also studied because of the scalar coupling between 195 Pt and other nuclei such as 13 C, 31 P, , or 35 Cl . To our knowledge, there are only three papers dealing with large 195 Pt CSAs, ,, from which K 2 PtCl 4 with a CSA of 6943 ppm is the largest yet determined for 195 Pt …”

Section: Resultsmentioning

confidence: 99%

Application of Multiple-Pulse Experiments to Characterize Broad NMR Chemical-Shift Powder Patterns from Spin-¹/₂Nuclei in the Solid State

2004

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The utility of the Carr-Purcell Meiboom-Gill (CPMG) experiment and a modified-CPMG experiment in characterizing NMR chemical-shift powder patterns for spin-1 / 2 nuclei is demonstrated. Heavier NMR-active nuclei such as 195 Pt, 199 Hg, and 207 Pb are known to be extremely sensitive to their local environment and as such have very large chemical-shift ranges. In the solid state, such nuclei commonly exhibit chemical shifts that range well over 1000 ppm, depending upon the orientation of the molecule within the applied magnetic field. Thus, acquiring NMR spectra of polycrystalline samples is often an experimental challenge because of these very broad powder patterns. In acquiring chemical-shift powder patterns of these nuclei, we provide several examples that demonstrate that a considerable saving in time is realized by using the CPMG experiment as opposed to the standard one-pulse or spin-echo experiment. In general, this time saving is even greater if a modified-CPMG experiment is used. Homonuclear dipolar interactions are considerably reduced in the CPMG experiment and are almost completely removed in the modified-CPMG experiment. For samples containing 1 H, larger enhancements are realized by combining the CPMG experiment with cross polarization. By use of the CPMG and the modified-CPMG experiments, the principal components of the chemical-shift tensors are determined for each of the samples studied.

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“…Estimates of the CSA in one Pt(II) complex have ranged from 900 ppm to 7500 ppm.2,4 Doddrell et al have circumvented several problems of solution state determinations by directly measuring platinum chemical shielding tensors in the solid state. 4 The two platinum(IV) compounds reported have anisotropies of 950 ppm and 1123 ppm. The investigators conclude shielding anisotropies may be considerably larger in the less symmetric tetra-coordinated platinum(II) complexes.…”

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confidence: 99%

Platinum-195 shielding tensors in potassium hexachloroplatinate(IV) and potassium tetrachloroplatinate(II)

Sparks¹,

Ellis²

1986

J. Am. Chem. Soc.

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Measurement of 195Pt chemical shift anisotropy in two solid Pt complexes, [Me3Pt(acetylacetonato)]2 and [Me3Pt]2SO4.4H2O. Effect on solution-state spin relaxation

Cited by 20 publications

References 1 publication

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

Application of Multiple-Pulse Experiments to Characterize Broad NMR Chemical-Shift Powder Patterns from Spin-¹/₂Nuclei in the Solid State

Platinum-195 shielding tensors in potassium hexachloroplatinate(IV) and potassium tetrachloroplatinate(II)

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Measurement of 195Pt chemical shift anisotropy in two solid Pt complexes, [Me3Pt(acetylacetonato)]2 and [Me3Pt]2SO4.4H2O. Effect on solution-state spin relaxation

Cited by 20 publications

References 1 publication

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

Synthesis and Molecular Structures of Perfluoro-n-alkyl Complexes of Platinum(II) and Platinum(IV) Containing Tetramethylethylenediamine (TMEDA) or 1,2-Bis(diphenylphosphino)ethane (DPPE) Ligands

Application of Multiple-Pulse Experiments to Characterize Broad NMR Chemical-Shift Powder Patterns from Spin-1/2Nuclei in the Solid State

Platinum-195 shielding tensors in potassium hexachloroplatinate(IV) and potassium tetrachloroplatinate(II)

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Product

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Application of Multiple-Pulse Experiments to Characterize Broad NMR Chemical-Shift Powder Patterns from Spin-¹/₂Nuclei in the Solid State