ChemInform Abstract: MERCURIERUNG DES BENZOLCHROMTRICARBONYLS

Abstract

Die Mercurierung der Verbindung (I) erfolgt mit Quecksilberacetat in Äthanol das mit Argon gesättigt ist.

Syntheses of Ortho-Mercurated and -Palladated (η6-Arene)tricarbonylchromium Complexes

“…In complexes 1b , 2b , and 3b the chelated −HgCl moiety results in almost no variation of k CO relative to 1a , 2a , and 3a , respectively, probably because of a chelation of the mercury atom by the intramolecular nitrogen Lewis base (Table , entries 1−3). Indeed, the values of Δ k CO related to the last three complexes are much lower than the large positive effect computed for (η 6 -C 6 H 5 -HgCl)Cr(CO) 3 (Table , entry 7), i.e., 5b , in which the apparently strong electron-withdrawing effect of −HgCl directly stems from the marked ionic character of the Hg−Cl bond and the attractive inductive effect of Cl. In the Ar 2 Hg-type complex 5c , a large negative value for Δ k CO is obtained (Table , entry 8).…”

“…Ortho Mercuration of Model ( η 6 -arene)Cr(CO) 3 Complexes. According to numerous reports, the preparation of metalated (η 6 -arene)tricarbonylchromium complexes can be carried out by not less than six direct ways: (1) low-temperature lithiation−deprotonation, , (2) ipso-S N Ar displacement of a halogen leaving group by a nucleophilic metal anion, (3) C−H bond activation, (4) oxidative addition of a metal to a C Ar −X bond and a Grignard type reaction, (5) CO extrusion from a metal−acyl complex, and, seldom reported, (6) electrophilic aromatic substitution or mercuration …”

“…A few examples of Friedel−Crafts type reactions carried out with (η 6 -arene)Cr(CO) 3 complexes showed that the conversions were quite low and the regioselectivities somewhat poor . As far as S E Ar reactions are concerned, only two reports describe the reaction of mercury(II) acetate, Hg(OAc) 2 , with (η 6 -arene)tricarbonylchromium complexes: for example, (η 6 -benzene)Cr(CO) 3 , (η 6 -toluene)Cr(CO) 3 , and (η 6 - N , N -dimethylaniline)Cr(CO) 3 . In all cases, the authors stated that the reaction worked fairly well with the benzene derivative (eq 1), while the toluene derivative reacted sluggishly and, surprisingly, the aniline derivative afforded no product at all.…”

Chloride-Promoted Synthesis of Cis Bis-Chelated Palladium(II) Complexes from Ortho-Mercurated Tricarbonyl(η6-arene)chromium Complexes

“…One alternative method of direct metalation of (η 6 -arene)Cr(CO) 3 complexes is the mercuration reaction by means of Hg(OAc) 2 , which affords compounds that are both temperature and air stable as well as reasonably reactive. Surprisingly, until recently, only three reports dealing with the matter were known . The sparseness of data on such an important reaction applied to (η 6 -arene)Cr(CO) 3 complexes was unusual, especially if one considers the “popularity” of organomercury(II) chemistry in the recent past and, of course, the amount of work published on the same topic for cymantrene, ferrocene, ruthenocene, and other metallocene derivatives .…”