Sonochemical ligand substitution temperatures

The transient nature of the cavitation event precludes conventional measurement of the conditions generated during bubble collapse. Chemical reactions themselves, however, can be used to probe reaction conditions. The effective temperature realized by the collapse of clouds of cavitating bubbles can be determined by the use of competing unimolecular reactions whose rate dependencies on temperature have already been measured. The sonochemical ligand substitutions of volatile metal carbonyls were used as... 

The sonolysis of Mn2(CO)10 makes for an interesting comparison (186), since either metal-metal (as in photolysis) (187) or metal-carbon (as in moderate temperature thermolysis) (188) bond breakage could occur. Ligand substitution will occur from either route producing the axially di-substituted Mn2(CO)8L2. Using benzyl chloride as a trap for the possible intermediacy of Mn(CO)5, the sonochemical substitution of Mn2(CO)10 has been shown to follow the thermal, rather than the photochemical, pathway of dissociative CO loss. 

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