Tris(trimethylsilyl)methane as an internal13C NMR chemical shift thermometer

Tris(trimethylsilyl)methane has excellent properties for an internal chemical shift thermometer to measure temperatures in 13C DNMR spectroscopy [Δδ between the 13C signals of Si(CH3)3 and CH carbons]. It is chemically inert, soluble in most organic solvents and has an almost linear dependence of Δδ on temperature. The sensitivity (approximately 1°C Hz-1 at 90 MHz) allows the measurement of temperature to within 1°C. The chemical shift is solvent dependent, so each solvent mixture must be calibrated. Calibrations are presented for seven solvents.