Irradiation of liquids with high-intensity ultrasound creates, via cavitation, localized hot spots with transient pressures of >300 atm and temperatures ~3000 K. We report the first studies of the chemical effects of ultrasound on Mn2(CO)10, MnRe(CO)10, and Re2(CO)10. Ultrasonic irradiation of Mn2(CO)10 produces ligand substitution by phosphines or phosphites. The rate of this substitution is independent of the choice of ligand or of its concentration, and the mechanism of substitution does not involve metal-metal bond cleavages. MnRe(CO)10 and Re2(CO)10 do not undergo sonochemical ligand substitution at appreciable rates, presumably because their lower vapor pressures preclude their presence in the cavitation event. In addition, we have found that Mn2(CO)10 and Re2(CO)10 undergo rapid sonochemical halogenation with halocarbon solvents, with rate enhancement of 105. The primary sonochemial event in these halogenations is homolysis of the solvent, generating halogen atoms (which can be trapped by M2(CO)10 or by alkane solvent) and carbon radicals (which dimerize and have been so characterized).
ASJC Scopus subject areas
- Colloid and Surface Chemistry