Thermal decomposition of some ruthenium carbonyl hydrides

The thermal stability of α-H₄Ru₄(CO)₁₂, H₄Ru₄(CO)₁₀P₂, H₄Ru₄(CO)₉P₃, H₄Ru₄(CO)₈P₄ (where P=triphenylphosphine) has been investigated by differential scanning calorimetry and by thermogravimetric analysis under argon dynamic atmosphere.The TG curves of the triphenylphosphine substituted derivatives of α-H₄Ru₄(CO)₁₂ suggest the release of the carbonyl and of the phenyl groups through a not well-defined pattern and overlapping decomposition reactions up to the retention of phosphorus in the residue, while α-H₄Ru₄(CO)₁₂ decomposes to metallic ruthenium. The decomposition heat of α-H₄Ru₄(CO)₁₂ and the isomerization heat of H₄Ru₄(CO)₈P₄ have been evaluated.