454253-18-0Relevant academic research and scientific papers
Thermal reactivity of Group 9 transition metal pinacolate complexes: Heterocumulene cleavage and C-O bond formation
Holland, Andrew W.,Bergman, Robert G.
, p. 99 - 106 (2008/10/08)
The reactions of Group 9 transition metal pinacolate complexes Cp*M(pin) (M=Co (1), Rh (2), Ir (3)) with heterocumulenes (Y=C=Z) are described. In these transformations the C=Z bond of the heterocumulene is cleaved, and the pinacolate ligand is incorporated into an organic heterocycle (pin)C=Y. In some cases a clean organometallic product of the general formula Cp*MZ2C=Y is also produced. The regiochemistry of these reactions has been explored and found to follow expected trends, and evidence suggests a mechanism involving initial heterocumulene insertion into an M-O bond yielding a 7-membered metallacycle, followed by 1,2 elimination.
Heterocumulene metathesis by iridium guanidinate and ureylene complexes: Catalysis involving reversible insertion to form six-membered metallacycles
Holland, Andrew W.,Bergman, Robert G.
, p. 9010 - 9011 (2007/10/03)
The four-membered metallacycles Cp*Ir((NAr)2C=Z) have been prepared for Z = NAr and Z = O. These complexes undergo facile exchange with free heterocumulenes. This exchange process can be employed to effect the rapid, catalytic metathesis of aryl carbodiimides at room temperature and the metathesis of aryl carbodiimides with aryl isocyanates at slightly elevated temperature. The exchange process appears to proceed via a novel associative mechanism involving ring expansion to form a six-membered metallacycle rather than cycloreversion to give an imido complex. Observation of key intermediates and the results of crossover experiments support this hypothesis. Copyright
