Reaction of metal carbonyl anions with electrophilic alkynes: Synthesis of isomeric η3-acryloyl and σ-vinyl complexes

摘要: Abstract Treatment of the metal carbonylate anions [CpMo(CO)2(L)]− (Cp = η-C5H5; L = PPh2Me, PPh2Et) with electrophilic alkynes methyl propiolate or DMAD (RC CCO2Me, where R = H CO2Me, respectively) followed by protonation affords η3-acryloyl (1-oxoallyl) complexes [CpMo(η3-COCR CHCO2Me)(CO)(L)] (3a–d) as major products, together isomeric vinyl trans-[CpMo(CR CHCO2Me)(CO)2(L)] (4a–d). On basis regioselectivity reaction, it is proposed that nucleophilic attack anion occurs at alkyne carbon bearing R; migration anionic ligand to a CO gives 3, whereas without insertion 4. The X-ray structures acryloyl complex [CpMo(η3-COCH CHCO2Me)(CO)(PPh2Me)] (3b) and its isomer [CpMo(σ-CH CHCO2Me)(CO)2(PPh2Me)] (4b) have been determined.