Argon-benzene complexes

In an atmosphere of argon, a solution of 13.5 g (88%, 94 mmol) of S.6b and 300 mg (11 mmol) of copper (I) trifluoromethanesulfonate benzene complex (CuOTf) in 120 mL of dry diethyl ether is irradiated in a Pyrex photoreactor with a water cooled quartz immersion well by a high-pressure mercury lamp (HPK 125 W, Fa. Philips). After the reaction is complete (monitored by GLC), the mixture is concentrated in vacuo and purified by column chromatography (cyclohexane/ethyl acetate 2 3) to give 10.5 g (64% from... 

The complex OsHCl(CO)(P Pr3)2 is a red, very air sensitive solid, which is, however, stable for long periods at room temperature if kept under argon. In the IR spectrum in benzene, the most noticeable feature is the presence of a v(CO) band at 1886 cm-1. At room temperature the 111 NMR spectrum in benzene- shows... 

It has been shown that ruthenium carbene complex lb developed for olefin metathesis can catalyze RCM of enynes. Using this catalyst lb, five- to nine-membered ring compounds 3 are synthesized from enyne 2 (Scheme j) i Sa-iSc The reaction procedure for RCM of an enyne is very simple. A benzene solution of enyne 2b is stirred in the presence of 1 mol% of ruthenium carbene complex lb at room temperature (RT) under argon gas to give cyclic compound 3b having a diene moiety. 

Figure 2. 12 K epr spectra of open-faced vanadiumbenzene sandwich and bis(benzene)vanadium sandwich complexes in solid argon. See text for details.

Anionic polymerization of IPTMSK and styrene was carried out at -78 °C in a Schlenk flask attached to a vacuum line. The reaction was carried out in benzene or benzene-THF (tetrahydrofuran) with an n-butyllithium-18-crown-6 complex as the initiator. The reaction was carried out under argon atmosphere and was quenched by injecting methanol into the polymerization mixture. 

Benzene, benzene-d , and fluorobenzene were found (770, 777) to react with chromium, cobalt, iron, and nickel atoms on codeposition in the neat ligand at 77 K, or in argon matrices at 10-12 K. IR studies of the products indicated that the initial reaction of these transition-metal atoms with an aromatic system is 7r-complex formation. Studies of ligand concentration-effects showed that the chromium-atom reaction is approximately second-order with respect to benzene, yielding the previously known (782) complex (CeH6)2Cr, whereas, with the other metals, the reaction is first-order, yielding MfCsHs), M = Co, Fe, or Ni. The absence of CrfCeH ) is probably a reflection of (a) the fact that the... 

Bludsky. O.. Spirko. V.. Hrouda. V.. and Hobza. P. (1992) Vibrational dynamics of the benzene/argon complex, Chem. Phys. Lett., 196, 410-416. 

The photochemical isomerization of the parent system 1 to cyclopropene (2) was first detected in an argon matrix at 8 K. The allene photoisomerizations most likely involve singlet intermediates employing benzene as a triplet sensitizer leads to complex mixtures containing structurally completely different isomers. A two-step mechanism whereby hydrogen migrates first to the central allene carbon atom, followed by either cyclization or a second 1,2-hydrogen shift from a vinylcarbene intermediate, accounts for the overall features of the allene cyclization. ... 

Numerous papers deal with the vibrational spectroscopy of charge-transfer complexes. Only a few recent papers are mentioned here because they deal with systems for which the possibility of performing deeper theoretical investigations in near future is very promising. The infrared spectra of the following complexes were studied in nitrogen (and argon) matrices H O... COj (for an ab initio study see Ref. ) HjN. .. CO/ , H,N. .. Cl/ , H,(). .. H O , benzene. .. Cl, Br, IC1 , benzene. .. I/ , H S. .. CH,O . 

---