The thermal degradation of three monosubstituted hexacarbonyl complexes, M(CO)spy (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 ofcarbonyl (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)spy 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.
The field of organometallic chemistry has grown very rapidly in the last two decades. This is largely due to the increasingly important roles of these compounds, particularly metal carbonyl complexes, in homogeneous and heterogeneous catalysis [1-3], thermal and photochemical polymerization reactions [4-6], and selective organic syntheses with low energy input requirements [7-8]. Many of these metal carbonyl complexes contain phosphorus and amine ligands which can greatly influence the rate and product of the reactions.Dissociation of a two electron ligand from eighteen electron species leading to sixteen electron intermediates plays a very important rote in organometallic compounds. Therefore, the knowledge on the thermal stabilities of the metal
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