TRIS(TRIMETHYLSILYL)METHANE AS AN INTERNAL C-13 NMR CHEMICAL-SHIFT THERMOMETER

Tris(trimethylsilyl)methane has excellent properties for an intern al chemical shift thermometer to measure temperatures in C-13 DNMR spectr oscopy [Delta delta between the C-13 signals of Si(CH3)(3) and CH carb ons]. It is chemically inert, soluble in most organic solvents and has an almost linear dependence of Delta delta on temperature. The sensit ivity (approximately 1 degrees C Hz(-1) at 90 MHz) allows the measurem ent of temperature to within 1 degrees C. The chemical shift is solven t dependent, so each solvent mixture must be calibrated. Calibrations are presented for seven solvents. (C) 1998 John Wiley & Sons, Ltd.