Low-temperature heat capacities of three molybdenum oxychlorides

Abstract

The heat capacities of MoO2Cl2, McOCl3, and MoOCl4 have been determined from 5 to 350 K. No thermal anomalies were detected over this temperature range. At 298.15 K the values of the heat capacity Cp, entropy So, and the function {Go(T) - Ho(0)/T} found were (for MoO2Cl2), 24.53, 32.42, and -16.71 kcalth K-1 mol-1; (for MoOCl3), 26.85 39.16, and -20.94 kcalth K-1 mol-1; and (for MoOCl4), 33.44, 48.28, and -25.80 kcalth K-1 mol-1. The derived functions stated above assume the extrapolation of the observed results from 0 to 5 K to follow the Debye limiting law; i.e., possible magnetic thermal anomalies below 5 K have not been included.