The Gas-Phase Electric Dipole Moments of the Symmetric Top Tertiary Butyl Molecules (t)BuX, X=F, Cl, Br, I, CN, and NC.

The electric dipole moments of symmetric top tertiary butyl derivatives were determined from Stark effect measurements made with cavity Fourier transform microwave spectroscopy under conditions of supersonic expansion. The resulting values are 1.9562(15), 2.1817(16), 2.2574(17) and 2.2122(17) D for tertiary butyl fluoride, chloride, bromide, and iodide, and 4.0129(30), and 4.0640(31) for tertiary butyl cyanide and isocyanide, respectively. The experimental values are compared with ab initio calculations and with experimental and calculated dipole moments for the corresponding methyl derivatives. Copyright 2001 Academic Press.