The heats of formation of SiCln and SiCln+, for n = 1-4, have been det
ermined using the G2(B3LYP/MP2/CC) approach. The results for the neutr
al systems are in very good agreement with previous work. High level c
alibration calculations allow us to refine the G2(B3LYP/MP2/CC) values
. While the computed and experimental IPs of SiCl4 agree, the calculat
ions show that the adiabatic TP is about 7 kcal/mol smaller than the a
ccepted value. The temperature dependence of the heat of formation, he
at capacity, and entropy are computed for 300 to 4000 K and fit to a p
olynomial. (C) 1997 Published by Elsevier Science B.V.