Characterization of the CH3F center dot BF3 van der Waals complex in the vapor phase

Using variable-temperature infrared spectroscopy, the vapor phase complexat ion enthalpy for the van der Waals complex CH3F . BF3 has been determined t o be -16.5(7) kJ mol(-1). This value is compared with literature values obt ained for solutions in liquid argon and in liquid krypton. The complexation enthalpy was transformed by statistical thermodynamics into a complexation enthalpy of -19.8(14) kT mol(-1), and this value is compared with ab initi o results in which the geometry of the complex is optimized at different le vels between MP2/6-31++G(d,p) and MP2/aug-cc-PVQZ, using BSSE-conected pote ntial energy surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.