1221000-41-4Relevant articles and documents
Reactions of alkynes with phosphido niobocenes: A combined experimental and theoretical study
Antinolo, Antonio,Garcia-Yuste, Santiago,Solera, Isabel Lopez,Otero, Antonio,Perez-Flores, Juan Carlos,Reguillo-Carmona, Rebeca,Villasenor, Elena,Santos, Eva,Zuidema, Erik,Bo, Carles
, p. 1962 - 1971 (2010)
The reactions of phosphido complexes [Nb(η5-C 5H4SiMe3)2(L)(PPh2)] [L = CO (1), CNxylyl (2), CNCy (3)] with alkynes have been carried out. The new diphenylphosphinoalkenyl niobocene complexes [Nb(η5-C 5H4SiMe3)2(η1-C- C(CO2CH3)C(R)PPh2)(CO)] [R = H (4), CH 3 (5)] and [Nb(η5-C5H4SiMe 3)2(η1-C-C(CO2R)C(CO 2R)PPh2)(CO)] [R = CH3, (6), R = tBu, (7)] were successfully synthesized by the reaction of 1 with methyl propiolate (HCCCO2CH3) or methyl 2-butynoate (CH3CCCO2CH3) and dimethyl 2-butynedioate [(CH3 O2C)CC(CO2CH3)] or di(tert-butyl) 2-butynedioate [(tBuO2C)CC(CO 2tBu)], respectively. However, reaction was not observed with more electron-rich alkynes. Complex 2 reacted with methyl propiolate, methyl 2-butynoate (MeCCCO2Me) or di(tert-butyl) 2-butynedioate to give surprising new heteroniobacycle complexes [Nb(η5-C 5H4SiMe3)2(η1-C- C(NXylyl)C(R1)C(R2)PPh2-κ1-P)] [R1 = H, R2 = CO2Me (8); R1 = Me, R2 = CO2Me (9); R1 = CO2 tBu, R2 = CO2tBu (10)]. Finally, the phosphido complexes 2 and 3 reacted with phenylacetylene (PhCCH) to give new diphenylphosphinoalkenyl niobocene derivatives [Nb(η5-C 5H4SiMe3)2(η1-C- C(C6H5)C(H)PPh2)(CNR)] [R = xylyl (11), Cy (12)]. All of these compounds were characterized by NMR spectroscopy and the molecular structure of 8 was determined by single-crystal X-ray diffraction studies. Theoretical studies were also carried out by means of density functional theory (DFT) calculations on the insertions of alkynes into the Nb-P bond in the phosphido niobocenes.
