Subject mercury halides

The catalytic activity of Hg in elimination and substitution reactions of transition-metal complexes continues to be the subject of study. Kinetic studies on the Hg" catalysed aquation of both cis-[Co(en)2(CN)Cl], cis-[(chloro)(aniline)CO(en)2], and [PdLX] (L = tetramethyldiethylenetriamine X = Cl, Br, or I) are consistent with intermediate adduct formation at the halide substituent. Mercury(ii) reacts reversibly with the [Co(NH3)5SCN] ion to yield [Co(NH3)5(SCN)Hg] which irreversibly undergoes either aquation to yield [Co(NH3)sH20] or isomerization to yield [Co(NH3)5(NCS)Hg] at approximately equal rates. The kinetics of the reaction... 

The last subject to be discussed in this section is one found with Group IV elements, and probably also with many Group II elements (cf. mercury, Section IV, E)—neighboring group effects and participation. Hawthorne (192) has pointed out that y-halopropylboranes, produced by hydroboration of allyl halides, undergo basic hydrolysis to yield cyclopropanes. 

Detectors Various detectors can be used in combination with GC for the determination of mercury species. An ECD is a sensitive detector with an absolute detection limit of a few picograms. It does not, however, measure mercury directly, but responds to the halide ion attached to the CH3Hg ion. The identification of small methylmercury peaks can sometimes be subject to a positive systematic error owing to coeluting contaminants. The use of a plasma atomic emission detector, a mass spectromet-ric detector, CV-AAS, CV-AFS, or ICP-MS can avoid such problems, since mercury is measured directly. 

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