Thermal degradation of transition metal carbonyl complexes. part iii. thermogravimetric and differential scanning calorimetric studies of triphenylphosphine pentacarbonyls of chromium, molybdenum and tungsten

Abstract

Thermogravimetric and differential scanning calorimetric studies on M(CO)5(PPh3) (M = Cr,Mo,W) revealed a sequential decomposition process which commenced at ca. 150°C. The Cr complex breaks down with a concurrent liberation of one PPh3 and two CO ligands. The Mo complex, however, eliminates two CO ligands stepwise, followed by the cleavage of the Mo-PPh3 bond. Expulsion of the PPh3 ligand in the W complex is facile, and occurs prior to the simultaneous elimination of the five CO ligands. Complete elimination of the ligands occurs readily in the latter complex below ca. 350 °C, which is consistent with a recent microcalorimetric study in the literature. The degradation pattern is dependent on the electronic and steric factors of the metal and ligands. © 1988.