Sydney Brownstein

A low-temperature thermometer for 1H, 19F, and 13C

Abstract A single sample is described which can be used with either proton, fluorine, or carbon resonance spectra to calibrate probe temperature down to -145°C. Calibration data are tabulated.

Intensity variations in two-dimensional multiquantum proton resonance spectroscopy: Design of a pulse sequence using the superspin formalism☆

Abstract The effect of the pulse sequence 90°− τ /2−180°− τ /2− α φ o − t 1 − β o -FID upon detection of homonuclear multiple-quantum transitions was analyzed for a two-spin system. The behavior with respect to flip angle (α and β) and phase (φ, ψ) were both considered. The theoretical predictions were experimentally verified. It is shown that the above sequence is much less sensitive to choice of τ than sequences previously described.

Universal referencing in multinuclear magnetic resonance spectroscopy

Abstract Universal referencing to a single species, e.g., TMS, may be employed even if there is no signal available for an internal lock. The importance of solvent effects on some common standards is shown.

Complex fluoroanions in solution—X: Complexes of phosphorus and arsenic fluorides with simple anions

Abstract Phosphorus and arsenic pentafluorides and arsenic trifluoride form 1:1 complexes with many simple anions. The hexafluoroanion and multiply anion substituted species are frequently formed from the pentafluoride complex. Phosphorus trifluoride reacts with some anions to give PF6− and other species.

PROTON AND FLUORINE RESONANCE SPECTRA OF SOME COMPLEXES OF PF5 AND AsF5

Abstract Chemical shifts, spin coupling constants and relative rates of quadrupole relaxation were determined for some complexes as a function of relative Lewis acid and Lewis base strength. Exchange behavior with an excess of acid or base was also studied.

Complex fluoroanions in solution—II: Reactions of boron trifluoride and phosphorus pentafluoride with group vb hexalfluoroanions☆

Complexing of boron trifluoride and phosphorus pentafluoride by solutions containing hexafluorotantalate and hexafluoroniobate ions occurs primarily by a disproportionation reaction to yield M2F11−, where M is tantalum or niobium. The relative complexing abilities of several fluoroanions towards boron trifluoride are listed.

Complexes of BrF3 with BF3, PF5 and AsF5

Abstract Fluorine resonance spectra of the complexes between BrF 3 and BF 3 or AsF 5 are interpreted as indicating a non-linear BrF 2 + attached by a fluorine bridge to the appropriate fluoroanion. Complexes with two equivalents of BF 3 , PF 5 and AsF 5 are also stable at low temperature.

Charge-transfer complexes of nitric oxide, tri or tetravalent halides and aromatic hydrocarbons

Abstract Complexes of nitric oxide, some aromatic hydrocarbons and the halides BF 3 , BCl 3 , AlCl 3 , FeCl 3 , SiCl 4 , GeF 4 , SnCl 4 and TiCl 4 have been identified and characterized by spectroscopic measurements.

Increased spectral dispersion via triple-quantum nuclear magnetic resonance

Abstract Triple-quantum proton resonance spectra were collected and assigned for several spin systems of common occurrence in organic compounds. The increased dispersion in the ω1 dimension allows one easily to resolve the CH3 signals in a mixture of CH3CH2CH2OH and CH3CH2CH2CHO.

Unfolding of two-dimensional spectra which are folded in the f1 dimension

Abstract To obtain the connectivity information of two-dimensional (2D) homonuclear correlated spectra with the same degree of resolution as chemical shift spin-coupling dispersed spectra normally requires much larger arrays of data. It is shown how two previously reported techniques may be modified and combined to yield this connectivity information with significantly smaller data arrays.