Mercury compounds, carbonylation

With respect to coal emissions, mercury, for example, was found to exist principally (as much as 96% ) in the elemental form (30). Previously, it was argued by some that ultraviolet radiation transformed it to the less toxic mercuric oxide (30). Sunlight tends to degrade mercurial compounds to the elemental form (47). Beryllium emissions from coal combustion may be in the nontoxic elemental form (46), but this is not known for certain. Fluoride, which is generally assumed to be 100% volatized (19), may be trapped with lime in particulates (33), but this also is questionable. Highly toxic nickel carbonyl (48) and arsine (49) emissions have not been reported to date, although the former is a distinct possibility (50). 

Phosphorus magnetic shielding tensors, general phosphido ligands in transition metal complexes, 1, 472 Phosphorus(III) mercury compounds, preparation, 2, 425-426 Phosphorus—metal complexes, characteristics, 2, 34 Phosphorus—nitrogen-containing rings, chromium carbonyl link, 5, 225... 

A point of practical interest is that the presence of metals in the compounds examined may result in the necessity for more frequent cleaning and/or replacement of sources than is necessary for conventional organic compounds. This has been reported to be the case with many metal carbonyls (244), and also for some tin and mercury compounds. 

The mercury compounds HgFe(CO)4 and Fe(CO)4(HgX)2 (X = C1, Br, I), which were the first representatives of non-ionic metal derivatives of iron carbonyl hydrides, were discovered by Hock and Stuhlmann (V, 36). During investigations into the preparation of cobalt carbonyls from cobalt halides under CO pressure, in the presence of another metal as a halogen acceptor, we discovered the mixed metal carbonyls M[Co(CO)4]2 (M = Zn, Cd, Hg, Sn) and M[Co(CO)4]3 (M = In, Tl) (44), e.g.,... 

Other factors affecting the diastereoselectivity in the metal hydride demercuration of a-mercury(II) carbonyl compounds have also been identified, which include the nature of the solvent, the amount of hydride used, the mode of addition, the nature of the hydride source and the ligand on mercury. The rationalization of these results is difficult. 

The cobalt carbonylates of Cd and In gave mixtures of dimers at the same concentrations at which Zn[Co(CO)4]2 also gave dimer mixtures. However, both catalysts also responded to Lewis acid cocatalysis. The mercury compound in itself was also unselective, but gave Binor-S in the presence of BPa O(C2H6)2. The catalyst In[Co(CO)4]3 did not produce a norbornadiene trimer. Concerted trimerization, though not completely unlikely, would require all three norbornadiene molecules in... 

Cycloaddition of carbon-carbon double bonds can also occur intramolecularly. Direct irradiation of simple dienes leads to cyclobutanes. This is a singlet-state process and is concerted. The stereochemistry of the cyclobutane can be predicted on the basis of orbital-symmetry rules (Part A, Section 10.1). Nonconjugated dienes can also undergo photochemical cyclization employing mercury or carbonyl compounds as sensitizers. Cyclobutane formation is usually unfavorable with 1,4-dienes because it would result in a very strained ring system. When the alkene units are separated by at least two carbon atoms, cyclization becomes more favorable sterically ... 

Mercury compounds 66,305,313 Metal alkene compounds 76, 304 Metal alkyl compounds 66, 296, 302 Metal alkyne compounds 84, 307 Metal ammine complexes 296. 309 Metal aryl compounds 158 Metal azides 92, 295. 321 Metal carbonyl compounds 121, 294, 295, 309, 314, 317 Metal cyano compounds 297, 303 Metal ethylene complexes 73, 296, 304 Metal halides 297, 303 Metal hexafluoro compounds 304 Metal hydrides 293, 323 Metal-ligand vibrations 292 Metal olefin compounds 73, 76, 296, 304... 

C = C triple bonds are hydrated to yield carbonyl groups in the presence of mercury (II) ions (see pp. 52, 57) or by successive treatment with boranes and H2O2. The first procedure gives preferentially the most highly substituted ketone, the latter the complementary compound with high selectivity (T.W. Gibson, 1969). 

Bisorganomercury compounds with carbonyl groups in the P- and P -positions (10.68) give arylmercury chloride (10.67) together with the dimer (10.69) of the organic residue that is bounded to mercury in the starting material (Hu et al., 1991 yields 10.67 64-98%, 10.69 50-63%). 

The mercuration of ferrocenylimines with Hg(OAc)2 has been studied. - 6 Mercuration occurs selectively at the a-position relative to the imine group to afford compounds 86a-i (Scheme gy107,108 The regioselectivity of these reactions points to the directing role of the Lewis-basic imine functionality. Similar factors probably play a role in the formation of the ferrocenylketone and ferrocenylaldehyde derivatives 87a-f and 87g-j, respectively. These derivatives readily react with amines to afford the corresponding imines (Scheme 9). Presumably, the Lewis-acidic mercury center of the monomercurated ferrocenylketones and ferrocenylaldehydes activates the carbonyl functionality toward nucleophilic attack by the amine. 

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

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