Formation of a zirconium—molybdenum bond via methane elimination

Rh4(CO)12-Catalyzed Hydroformylation of Cyclopentene Promoted with HMn(CO)5. Another Example of Rh4(CO)12/HMn(CO)5 Bimetallic Catalytic Binuclear Elimination

“…It can be noted that after the simultaneous addition of the manganese carbonyls HMn(CO) 5 and Mn 2 (CO) 10 and hydrogen to the systems initially containing Rh 4 -(CO) 12 , alkene, hexane, and CO, the concentrations of Rh 4 (CO) 12 monotonically decreased and the concentration of RCORh(CO) 4 monotonically increased for the first 6 h. However, the data presented in Figure 3 indicate that the decrease of Rh 4 (CO) 12 and increase of RCORh(CO) 4 are not simple monotonic functions at initial reaction times. Indeed, upon addition of Mn 2 -(CO) 10 , HMn(CO) 5 , and H 2 , a rapid decline in the catalyst precursor concentration and a corresponding increase in acyl complex concentration occur.…”

“…16 Hydroformylation of alkene in the presence of tetrarhodium dodecacarbonyl alone has been extensively studied at low temperatures. 17 In the present Rh 4 (CO) 12 /HMn(CO) 5 bimetallic catalyzed hydroformylation of cyclopentene (CP), the chemometric analysis of the in situ infrared spectra of the reaction recovered the following: the precursors Rh 4 -(CO) 12 , HMn(CO) 5 , and Mn 2 (CO) 10 , the organic reagent cyclopentene, the rhodium intermediate RCORh(CO) 4 , and the organic product cyclopentanecarboxaldehyde. Similar to the results of the Rh 4 (CO) 12 /HMn(CO) 5 -catalyzed hydroformylation of 33DMB, 10 no Rh-Mn complex analogous to MnCo(CO) 9 2m was observed in Rh 4 (CO) 12 /HMn(CO) 5 -catalyzed hydroformylation of the cyclopentene system.…”

“…60 min when 150.25 mg of Mn 2 (CO) 10 was used, whereas a half-life under similar reaction conditions for pure Rh systems is ca. 2 h. This atypical initial time behavior is indicative of the existence of a second parallel precatalytic pathway for the transformation of Rh 4 (CO) 12 to RCORh(CO) 4 in the presence of manganese carbonyls: namely, the hydride-facilitated degradation of the cluster Rh 4 (CO) 12 . It should be mentioned that the effects observed in the present study were also observed in the Rh 4 (CO) 12 /HMn(CO) 5 /3,3-dimethylbut-1-ene system.…”

“…Generally speaking, the higher the concentration of HMn(CO) 5 , the faster the transformation of Rh 4 (CO) 12 to RCORh(CO) 4 . Moreover, the half-life for Rh 4 (CO) 12 in the mixed Rh 4 (CO) 12 /HMn-(CO) 5 system is ca.…”

“…When M 1 and M 2 are the same element, the stoichiometric binuclear elimination is homometallic. In perhaps the first known case, Heck and Breslow identified such a reaction pathway involving an intermolecular hydride transfer between HCo(CO) 4 and CH 3 COCo(CO) 3 to eliminate the dinuclear complex Co 2 (CO) 8 and aldehyde product. 1 Additonal examples of homometallic stoichiometric binuclear elimination have been identified.…”