Standard Heats and Free Energies of Formation and Absolute Entropies of 2-Chloro-2-methylpropane
$\Delta H_\mathrm{f}^\circ = -211.3~\mathrm{kJmol^{-1}}$ 

Neither source provided entropy or free energy data though but this is a start.

http://courses.chem.indiana.edu/c360/documents/thermodynamicdata.pdf
    http://webbook.nist.gov/cgi/cbook.cgi?ID=C507200&amp;Units=SI&amp;Mask=2#Thermo-Condensed