Molecular conformation trapping as an aid to chemical shift assignments for multi-conformation systems: A platinum(II) complex
✍ Scribed by Linda A. Luck; Wendy L. Elesser; John L. Hubbard; C. Hackett Bushweller
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 215 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Recent work in our laboratory has shown that 31P{1H} dynamic NMR (DNMR) spectroscopy is useful in studying restricted rotation about the metal-phosphorus bonds in bulky bis-phosphine-di-halo complexes of platinum(I1). Decoalescence is observed and the 31P{1H} NMR chemical shift is clearly sensitive to changes in molecular conformation. However, in most instances, the spectrum of a given conformation is a simple singlet which inherently contains no information regarding molecular geometry. Assignment of a given singlet to a specific conformation is problematic. A method is described for obtaining unequivocal assignment of NMR signals to specific molecular conformations by using DNMR spectroscopy, x-ray crystallography and dissolution of the conformationally homogeneous crystals a t very low temperatures ('molecular conformation trapping'). This methodology should be useful for the analysis of any multi-conformation system which has a sufficiently high energy barrier to conformational equilibration.
KEY WORDS Bisphosphine platinum(I1) complex Molecular conformation trapping 31P{ 'H} chemical shift assignments