Mercury, carbene complexes

Diethylzinc l,3-bis(l-adamantyl)imidazol-2-ylidene adduct is known (93JOM(462)13). Bis(l,3-diphenylimidazol-2-ylidene) mercury(II) carbene complexes follow from the corresponding imidazolium perchlorate and mer-cury(II) chloride (68AGE682). 

Structures of Organomercury Compounds 2.07.1.4.1 Mercury carbene and carbonyl complexes... 

Bis(butadiene) complexes, with tantalum, 5, 173 Bis(z-butanethiolato) complexes, with bis-Cp Ti(IV), 4, 601 Bis(calixarene) complexes, as organic molecule hosts, 12, 799 Bis(carbene) complexes with gold(I), 2, 287-288 with manganese, 5, 780, 5, 826 with mercury, 2, 429 with palladium, 8, 230 with silver , 2, 206... 

As mentioned earlier, the carbene ligand in our complexes shows nucleophilic character with respect to the metal fragment. Therefore, we decided to combine it with an electrophilic carbene. For this purpose we treated pentacarbonyl[methoxy(phenyl)carbene]chromium(0) with phenyl(tri-chloromethyl) mercury (85). Compounds of this kind have been studied intensively by Seyferth et al. (86) and are known as a source of dihalogeno-carbenes. The carbene complex reacted with the carbenoid compound at... 

H.-W. Wanzlick, and H.-J. Schonherr, Direct Synthesis of a Mercury Salt-Carbene Complex, Angew. Chem. Int. Ed. Engl. 7, 141-142 (1968). 

Note The cationic mercury(II) carbene complex in Figure 3.74 shows Hg-0 distances that are consistent with Hg-0 bond lengths in mercury crown ether complexes [212]... 

Despite their apparent steric bulk, both the Fc and bis-ferrocenyl modified carbene ligands could be successfully i Ued in the synthesis of mono- and bis-carbene complexes of mercury(II) [147], mngsten(0) [147], palladium(II) [147,183,192] andsilver(I) [191] (see Hgure 4.57). 

Figure 4.60 Synthesis of Cp-metallated annulated Cp-NHC ligands and their mercury(ll) carbene complexes.

Note The above mercury complex is the first purine transition metal carbene complex... 

Figure 6.35 Synthesis of a mercury bis-carbene complex using N -methylated caffeine as the...

Wanzlick HW, Schonherr HJ (1968) Direct synthesis of a mercury salt-carbene complex. Angew Chem Int Ed Engl 7 141-142... 

Luger P, Ruban G (1971) Crystal structure of a mercury salt-carbene complex. Acta Crytallogr Sect B 27 2276-2279... 

The O-alkylation of acyl mercurials produces cationic carbene complexes (Gerhart and Schollkopf, 1967). Similar procedures have been used to prepare... 

In the early 1960s, Wanzlick published the first investigations concerning the chemistry of NHCs [19]. In 1968, the synthesis of first stable crystalline transition metal-carbene complexes based on imidazolium salts with mercury(II) and chromium(O), respectively, were published [20, 21]. In the following years, NHCs... 

More useful for synthetic purposes, however, is the combination of the zinc-copper couple with methylene iodide to generate carbene-zinc iodide complex, which undergoes addition to double bonds exclusively to form cyclopropanes (7). The base-catalyzed generation of halocarbenes from haloforms (2) also provides a general route to 1,1-dihalocyclopropanes via carbene addition, as does the nonbasic generation of dihalocarbenes from phenyl(trihalomethyl)mercury compounds. Details of these reactions are given below. 

The cationic carbene-mercury complex 22 was prepared more than 30 years ago (3) via the reaction of 1,3-diphenylimidazolium perchlorate 5 (R = Ph R = H) with mercuric acetate. The same synthetic approach has been used more recently for the preparation of the analogous l,3-dimethylimidazol-2-ylidene complex, 23 (20). Thus, although 22 possesses a linear carbene-Hg-carbene skeleton (21), that of 23 is distorted toward a tetrahedral arrangement (C(carbene)-Hg-(C(carbene)) = 161.4(3)°) due to interactions with the chloride anions... 

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