98652-44-9Relevant academic research and scientific papers
Mechanistic study of the reactions of 1,1-dimethylallene with nickel(O) complexes. π- and σ-complex formation vs. electron transfer
Pasto, Daniel J.,Huang, Nai-Zhong
, p. 1386 - 1395 (2008/10/08)
The reactions of 1,1-dimethylallene (DMA) with several Ni(0) complexes have been studied. Kinetic and NMR studies on the reaction of DMA with tris(triphenylphosphine)nickel(0) [(TPP)3Ni] indicate the formation of mono(1,1-dimethylallene)-, cis- and trans-bis(1,1-dimethylallene)-, and tris(1,1-dimethylallene)nickel complexes, the ratio of the complexes depending on the concentration of DMA and added TPP. At temperatures below -60°C the cis-bis(DMA) π-complex [and possibly the tris(DMA) π-complex] undergoes coupling to form mainly the 3,4-bis(isopropylidene)nickelacyclopentane complex 30. At temperatures above -15°C, 30 undergoes hydrogen atom migration and reductive elimination to form 12. The reaction of tris(triethylphosphine)nickel(0) with DMA also results in the formation of 12; however, the extent of mono-, bis-, and tris(DMA) π-complex formation is much less. In contrast, DMA reacts with (COD)2Ni in an electron-transfer process to initially form the DMA radical anion. The overall reaction is very complex. Carbonylation of the finally derived complex(es) produces the two isomeric, trimeric ketones 22 and 24. The reaction of DMA with the mixed-ligand complexes (cyclooctadiene)(triphenylphosphine)nickel(O) and (cyclooctadiene)(ethyl acrylate)nirkel(0) proceed in a manner similar to that with the substituted-phosphine complexes.
