77922-78-2Relevant academic research and scientific papers
Unequivocal proof of slowed chromium tricarbonyl rotation in a sterically crowded arene complex: An X-ray crystallographic and variable-temperature high-field NMR study of (C6Et5COCH3)Cr(CO)3
Downton,Mailvaganam,Frampton,Sayer,McGl inchey
, p. 27 - 32 (1990)
The low-temperature 13C NMR spectrum of (C6Et5COCH3) Cr(CO)3 is explicable only in terms of a single sterioisomer, i.e., the 1-proximal-acetyl-2,4,6-distal-3,5-p roximal conformer. The Cr(CO)3/s
Carbon-carbon bond formation reaction of zirconacyclopentadienes with alkynes in the presence of Ni(II)-complexes
Takahashi, Tamotsu,Tsai, Fu-Yu,Li, Yanzhong,Nakajima, Kiyohiko,Kotora, Martin
, p. 11093 - 11100 (2007/10/03)
Zirconacyclopentadienes, prepared from two alkynes or a diyne, reacted with the alkyl-, trimethylsilyl-, or alkoxy-substituted third alkyne as well as an alkyne with an electron-withdrawing group in the presence of a stoichiometric amount of NiBr2(PPh3)2 to give benzene derivatives in good yields. Heteroatom-containing diynes such as dipropargylbenzylamine and propargyl-homopropargylbenzylamine gave isoindoline and tetrahydroisoquinoline derivatives in good to high yields. This procedure was also used for the selective preparation of benzene derivatives from three different alkynes. The use of trimethylsilyl-substituted alkyne as the first, second or third alkyne afforded desilylated benzene derivatives. The reaction of zirconacyclopentadienes with allenes gave benzene derivatives as a mixture of two isomers.
Charge-transfer probes for molecular recognition via steric hindrance in donor-acceptor pairs
Rathore,Lindeman,Kochi
, p. 9393 - 9404 (2007/10/03)
Molecular association of various aromatic hydrocarbons (D, including sterically hindered donors) with a representative group of diverse acceptors (A = quinone, trinitrobenzene, tetracyanoethylene, tropylium, tetranitromethane, and nitrosonium) is visually apparent in solution by the spontaneous appearance of distinctive colors. Spectral (UV-vis) analyses of the colored solutions reveal their charge-transfer origin (λ(CT)) and they provide quantitative information of the intermolecular association in the form of the K(DA) and ε(CT) values for the formation and visualization, respectively, of different [D,A] complexes. Importantly, such measurements establish charge-transfer absorption to be a sensitive analytical tool for evaluating the steric inhibition of donor-acceptor association. For example, the steric differences among various hindered aromatic donors in their association with quinone are readily dramatized in their distinctive charge-transfer (color) absorptions and verified by X-ray crystallography of the charge-transfer crystals and/or QUANTA molecular modeling calculations of optimum intermolecular separations allowed by van der Waals contacts.
