Metallacycle Expansion by Alkyne Insertion. Chemistry of a New Family of Ruthenium Organometallics
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- 作者：Kaushik Ghosh ; Sujay Pattanayak ; and Animesh Chakravorty
- 刊名：Organometallics
- 出版年：1998
- 出版时间：May 11, 1998
- 年：1998
- 卷：17
- 期：10
- 页码：1956 - 1960
- 全文大小：94K
- 年卷期：v.17,no.10(May 11, 1998)
- ISSN：1520-6041
文摘
Acetylene and phenylacetylene reacts withcarbonylchloro[4-methyl-6-((R-imino)methyl)phenolato-C,O]bis(triphenylphosphine)ruthenium(II),Ru(RL1)(PPh3)2(CO)Cl(3), affordingthe inserted productcarbonylchloro[2-vinyl-4-methyl-6-((R-imino)methyl)phenolato-C,O]bis(triphenylphosphine)ruthenium(II),Ru(RL2,X)(PPh3)2(CO)Cl(4), in virtually quantitativeyield. The X-ray structures of 4b (R = X = Ph) and4g (R = Et, X = H) have revealed thepresence of distorted-octahedral RuC2P2ClOcoordination spheres. In the conversion 3 
4,the Ru(C,O) chelate ring expands from four-membered tosix-membered. The insertion ofphenylacetylene is regiospecific, and a reaction model implicatinginitial Ru-O cleavageand steric control is proposed. The Ru-O bond in 4 issignificantly shorter (by ~0.14 Å)and stronger than that in 3. This is reflected in thelowering of the ruthenium(III)-ruthenium(II) reduction potential by ~200 mV. Theuncoordinated Schiff base moiety in 4is present in the hydrogen-bonded iminium-phenolato zwitterionicform, as revealed bythe N···O distance as well as by IR and NMR data.
4,the Ru(C,O) chelate ring expands from four-membered tosix-membered. The insertion ofphenylacetylene is regiospecific, and a reaction model implicatinginitial Ru-O cleavageand steric control is proposed. The Ru-O bond in 4 issignificantly shorter (by ~0.14 Å)and stronger than that in 3. This is reflected in thelowering of the ruthenium(III)-ruthenium(II) reduction potential by ~200 mV. Theuncoordinated Schiff base moiety in 4is present in the hydrogen-bonded iminium-phenolato zwitterionicform, as revealed bythe N···O distance as well as by IR and NMR data.