Thermal degradation of transition metal carbonyl complexes. Part II - Thermogravimetry and differential scanning calorimetry of monosubstituted pyridine carbonyls of chromium, molybdenum and tungsten

Abstract

The thermal degradation of three monosubstituted hexacarbonyl complexes, M(CO)5py (where M=Cr, Mo, and W; py=pyridine) has been studied by thermogravimetry (TG) and differential scanning calorimetry (DSC) and their results reported. It was found that for each of the three complexes studied, the starting material M(CO)6 was formed which immediately sublimed unchanged with or without concomitant loss of carbonyl (CO) ligands to give the first large weight loss step. This was closely followed by the volatilisation of the pyridine ligands and at higher temperatures the loss of further CO ligands. The enthalpy changes associated with the above-mentioned steps are reported. The conversion of M(CO)5py to M(CO)6 and other products was confirmed by the analysis of residue after pyrolysis in a tube furnace under conditions similar to those observed in TG experiments. © 1988 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest.