1. Purpose

The nuclides ⁴⁷Ti and ⁴⁹Ti (I = 5/2 and 7/2, natural abundance 7.28% and 5.51%) are a curiosity since they are the only isotopes of the Periodic Table the signals of which appear together in a single NMR spectrum. Therefore one always gets two titanium signals, separated by 266 ppm, even if only one chemical species is present. Furthermore, both nuclides have a quadrupolar moment and a relatively low gyromagnetic ratio, and therefore methods for suppressing probe-head ringing can be tested with these nuclides. Titanium organic catalysts are of prime importance in modern synthetic organic chemistry; unfortunately, in many cases NMR spectroscopy fails to obtain a signal at all from these nuclides. In this experiment we demonstrate the observation of the titanium signals using TiCl₄.

2. Literature

C. D. Jeffries, H. Loeliger, H. H. Staub, Phys. Rev. 1952, 85, 478–479; C. D. Jeffries, ibid. 1953, 92, 1262–1263.
N. Hao, B. G. Sayer, G. Denes, D. G. Bickley, C. Detellier, M. J. McGlinchey, J. Magn. Reson. 1982, 50, 50–63.
D. Rehder in Multinuclear NMR, J. Mason (ed.), Plenum Press, New York, 1987, 487–488.
S. Berger, W. Bock, C. F. Marth, B. Raguse, M. T. Reetz, Magn. Reson. Chem. 1990, 28, 559–560.
S. Berger, W. Bock, G. Frenking, V. Jonas, F. Müller, J. Am. Chem. Soc. 1995, 117, 3820–3829.

3. Pulse Scheme and Phase Cycle

Experiment a

Standard pulse sequence for titanium-47 and titanium-49 NMR