158569-95-0Relevant academic research and scientific papers
Formation of pentadienal complexes upon protonation of molybdenum (1-alkylcyclopropyl)carbynes. Electronic effects on reductive elimination versus β-hydrogen elimination in metallacyclohexenones
Mortimer, Mark D.,Carter, John D.,Kingsbury, Kevin B.,Abboud, Khalil A.,McElwee-White, Lisa
, p. 8629 - 8637 (2007/10/02)
The (1-alkylcyclopropyl)carbynes (η5-C5H5)(CO){P(OMe) 3}Mo≡CC(R)CH2CH2 [R = CH2CH=CH2 (3a), CH3 (3b), SCH3 (3c), CH2C6H5 (3d)] have been prepared and characterized. Reaction of 3a-d with HCl·Et2O yields mixtures of the η4-2,4-pentadien-1-al complexes (η5-C5H5)Cl{P(OMe)3}Mo{CH 2=CHC(R)=CH(CHO)} (4a-d) and the η2-acyl complexes (η5-C5H5)Cl2{P(OMe) 3}Mo{η2-C(O)CH2C(R)CH2CH 2} [R = CH3 (5a), SCH3 (5b)]. Only one isomer of 4a-d forms initially, but over a period of days, there is interconversion of a series of isomers. Formation of dienal complexes 4a-d when R is an electron-donating group contrasts with the previously observed formation of cyclopentenones from derivatives of 3 where R = H, COR′, and CO2R′. These results are consistent with an electronic effect on the partitioning between reductive elimination and β-hydrogen elimination in a metallacyclohexenone intermediate. Complexes 3b and 3c oxidize slowly in CHCl3 to give the dichloro derivatives (η5-C5H5)Cl2{P(OMe) 3}-Mo≡CC(R)CH2CH2 [R = CH3 (6a), SCH3 (6b)]. The structures of 4b and 6a have been determined by X-ray diffraction: (4b) monoclinic, P21/n, a = 10.188(1) A?, b = 11.666(1) A?, c = 14.128(2) A?, β = 90.73(1)°, V = 1679.0(8) A?3, Z = 4, R = 4.33, Rw = 5.09% for 2826 reflections I > 3σ(I); (6a) orthorhombic, P212121, a = 9.480(1) A?, b = 13.383(1) A?, c = 13.585(1) A?, V = 1723.5(3) A?3, Z = 4, R = 4.41, Rw = 4.96% for 2024 reflections I > 2σ(I).
