Quasi-Complex Compounds

The arylation reactions described in this section were used not only synthetically but also for analysis of structures of quasi-complex compounds of mercury. 

The first structure, if arylated by C HjSnOOH in alkaline medium according to the procedure developed by us [see above (55)], should lead to diphenylmercury and ethylene, while the second structure should give the unsymmetrical organomercurial HOCH2CH2HgCjH5. 

In reality, the second possibility occurred (57), and the same was true for the adducts containing other olefins. Finally, we verified the presence of hydroxyl in structure (IV) through reaction with phenyl isocyanate. Thus, the convincing experiments of Hoffmann, Middleton, and R. Adams were confirmed by our decisive evidence, so that 7T-structures were condemned to fade from the scene for these compounds. However, to emphasize the behavioristic similarity with the 77-complcxes, I suggested the term quasicomplex for the compounds which are formed from metallic salts and olefins or acetylenes through addition to the 7T-bond. A number of such quasi-complex compounds were obtained and studied by us. In particular, we showed that butadiene or its homologs, contrary to the earlier opinion of Sand, also formed the quasi-complex adducts in water, e.g., 

Other adducts were also prepared, namely, those of allylcyclopentane, 2-allyldecalin, diallyl ether, and diallylamine. The latter three compounds are oxygen or nitrogen-heterocycles. They all are quasi-complexes [Nes-mayanov, Lutsenko 58, 59)  

With the adducts from mercury dichloride and acetylene, we [Nes-meyanov, Freidlina, Borisov (60-62)] began the investigation by studying the compounds of Biginelli and Jenkins for which either n or o-structures, or tautomerism between these might be assumed. 

---

Why do quasi-complex compounds liberate acetylene or olefin so... 

Again, as with all conjugated systems, as well as the quasi-complex compounds, the 1,4-attack takes place so that the 3,4 a- and the 1,2 77-bonds are broken, while the 2,3 77-bond is formed. The process very probably involves a six-membered transition state. A four-membered state may participate in C-alkylation where the reaction site is not transferred. 

The quasi-complex compounds, as well as the complexes discussed above, led us into a domain which was nearly terra incognita at that time, namely, the substituted (j3-chloro, j8-alkyl, )3-keto) vinyl organometallics. Thus, the simplest of metal vinyls became the objective of our work, and the vinyl, isopropenyl, propenyl, and styryl derivatives of elements such as Hg, B, Tl, Ge, Sn, Si, P, As, Sb, and Bi were studied in collaboration with Freidlina and Borisov. Apart from the procedures mentioned in Section V, vinyl-lithium and vinyl Grignard compounds were used for the synthesis. Note that the highest valence alkenyl derivatives of the type RjSb were reported by us (181-205). 

The methods described above are appropriate for simple ions, but not for the calculation of the activity coefficients of more complex compounds such as zwitterions, i.e., those which bear more than one functional group, have a low molecular weight, which is arbitrarily put at less than 500, and are approximately spherical in shape so that both the quasi-spherical assumption used in the van der Waals integral and the present definition of cavity area are satisfied. Many substances of interest... 

Two crystal structures have been determined so far (25, 26),the most recent result showing the Mn(II) complex to be a quasi-sandwich compound with the metal being attached predominantly to the benzylic carbon atoms (26). As in the Cd(II) complex, the compound has a C2 axis (Fig. A) through the metal. 

The compounds (VIII) and (IX) display their quasi-complex properties less clearly than do (VI) and (VII). Their trans isomers lose acetylene much more easily than do the cis ones. 

Finally, note that the ions produced by the combined inlet and ion sources, such as electrospray, plasmaspray, and dynamic FAB, are normally molecular or quasi-molecular ions, and there is little or none of the fragmentation that is so useful for structural work and for identifying compounds through a library search. While production of only a single type of molecular ion may be useful for obtaining the relative molecular mass of a substance or for revealing the complexity of a mixture, it is often not useful when identification needs to be done, as with most general analyses. Therefore,... 

Gold(I) ylides are oxidized in 0.1 M [Bu4N]BF4/THFat low potentials of +0.11 and + 0.23 V vs. Ag/AgCl (quasi-reversible). The dinuclear amidinate oxidizes under the same conditions at + 1.24 V vs. Ag/AgCl (reversible). These large differences in chemical character of the dinuclear gold(I) complexes appear to explain the widely different behavior of these compounds and especially toward the reaction with mercury cyanide. 

Fig. 4.3 Ranges of isomer shifts observed for Fe compounds relative to metallic iron at room temperature (adapted from [24] and complemented with recent data). The high values above 1.4-2 mm s were obtained from Co emission experiments with insulators like NaCl, MgO or Ti02 [25-28], which yielded complex multi-component spectra. However, the assignment of subspectra for Fe(I) to Fe(III) in different spin states has never been confirmed by applied-field measurements, or other means. More recent examples of structurally characterized molecular Fe (I)-diketiminate and tris(phosphino)borate complexes with three-coordinate iron show values around 0.45-0.57 mm s [29-31]. The usual low-spin state for Fe(IV) with 3d configuration is 5 = 1 for quasi-octahedral or tetrahedral coordination. The low-low-spin state with S = 0 is found for distorted trigonal-prismatic sites with three strong ligands [30, 32]. Occurs only in ferrates. There is only one example of a molecular iron(VI) complex it is six-coordinate and has spin S = 0 [33]...

---