168097-38-9Relevant academic research and scientific papers
Methyl/phenyl exchange between palladium and a phosphine ligand. Consequences for catalytic coupling reactions
Morita, David K.,Stille,Norton, Jack R.
, p. 8576 - 8581 (2007/10/03)
The methyl ligand of trans-CH3Pd(PPh3)2I (1) exchanges with a phenyl from its PPh3 ligand, initially giving PhPd(PPh3)(PMePh2)I (4). The PMePh2 ligand of 4 then exchanges with a PPh3 of 1 to give CH3Pd(PPh3)-(PMePh2)I and with the PMePh2 ligand of more 4 to give PhPd(PPh3)2I and trans-PhPd(PMePh2)2I. The observed rate constant for the disappearance of 1 is about 7 × 10-5 s-1 at 75 °C. The rearrangement is irreversible, does not involve a free phosphonium cation, and does not require phosphine dissociation. The rearrangement competes with transmetalation when 1 is treated with tin reagents, leading to coupling products incorporating phenyls from PPh3. Relatively electropositive phosphine substituents seem reluctant to rearrange onto palladium.
