874300-16-0Relevant academic research and scientific papers
Intramolecular metathesis of a vinyl group with vinylidene C=C double bond in Ru complexes
Yen, Yung-Sheng,Lin, Ying-Chih,Huang, Shou-Ling,Liu, Yi-Hung,Sung, Hui-Ling,Wang, Yu
, p. 18037 - 18045 (2007/10/03)
The cationic complex {[Ru]=C=CHCPh2CH2CH=CH 2}BF4 (3a, [Ru] = (η5-C5H 5)(PPh3)2Ru) in solution transforms to {[Ru]=C=CHCH2CPh2CH=CH2}BF4 (4a) via a new metathesis process of the terminal vinyl group with the C=C of the vinylidene group which is confirmed by 13C labeling studies. This transformation is irreversible as revealed by deuteration and decomplexation studies. The cationic complex {[Ru]=C=CHCPh2CH2CMe=CH 2}BF4 (3b) undergoes a cyclization process yielding 6b containing a η2-cyclic allene ligand which is fully characterized by single-crystal X-ray diffraction analysis. Analogous complexes 4a′ and 6b′ ([Ru] = (η5-C5H5)(dppe)Ru) containing dppe ligands were similarly obtained from protonation of the corresponding acetylide complexes via formation of vinylidene intermediate. Protonation of the acetylide complex containing a terminal alkynyl group [Ru]-C≡CCPh2CH2C≡CH (2c) generates the vinylidene complex {[Ru]=C=CHCPh2CH2C≡CH}BF 4 (3c) which again undergoes an irreversible transformation to give {[Ru]=C=CHCH2CPh2C=CH}BF4 (4c) possibly via a π-coordinated alkynyl complex followed by hydrogen and metal migration. No similar transformation is observed for the analogous dppe complex 3c′. With an extra methylene group, complex {[Ru]=C=CHCPh2CH 2CH2CH=CH2}BF4 (3d) and complex {[Ru]=C=CHCPh2CH2Ph}BF4 (3e) are stable. The presence of a gem-diphenylmethylene moiety at the vinylidene ligand with the appropriate terminal vinyl or alkynyl group along with the correct steric environment implements such a novel reactivity in the ruthenium vinylidene complexes.
