Main Group Metal Derivatives

The same synthetic procedure has been applied to the preparation of main group metal derivatives of corrole [25]. Thus Sn(OMC)X, Ge(OMC)X and In(OMC) (where X is chloride or acetate) have been prepared starting from SnCl2, GeCl4 and InCl3. 

The transfer of main group metal derivatives can be achieved efficiently using aluminum derivatives, but the stereoselectivity is now syn, suggesting initial transfer of the metalloid to the Pd (Scheme 16). 

Metal acetates have been used as reagents in the metathesis with alkaU alkoxide mainly in order to produce the main group metal derivatives, for example, the homologous smies of lead aUcoxides (Papiemik, 1989 Turevskaya, 1982). The reaction produces the insoluble sodium acetate that can be removed by filtration or decantation. It should be mentioned that, when carried out in toluene (on reflux) it could very easily lead to oxoalkoxide derivatives via ester or ether elimination side reactions (see Method 1.3). 

The oligomers obtained with these systems follow a Schulz-Flory type distribution. The nickel catalyst complexes can be divided into two groups nickel(ll) compounds modified with alkyl or hydride main-group metal derivatives (Ziegler-Natta type catalyst) and chelated nickel compounds with a Ni-C bond. 

Dienes and allylarcncs can be prepared by the Pd-catalyzcd coupling of allylic compounds with hard carbon nucleophiles derived from alkenyl and aryl compounds of main group metals. Allylic compounds with various leaving groups can be used. Some of them are unreactive with soft nucleophiles, but... 

M[TpRR ] complexes (M = Li, Na, Cs, R4N+) may also be obtained by the reactions of the monoprotonated derivative H[TpRR ] with MOH (lb). Both the M[TpRR] and M[BpRR] complexes are useful starting materials for the preparation of poly(pyrazolyl)borato complexes of both the transition and main group metals. 

Syntheses of aryl organometallics other than polyhalogenoaryls by thermal decarboxylation are comparatively rare. There are several reasons for this. For transition elements, the thermal stability of simple aryls is often low, especially by comparison with polyhalogenoaryl derivatives, thereby excluding syntheses at elevated temperatures. Electron-withdrawing substituents frequently aid thermal decarboxylation (Section III,A-D), and their absence inhibits major mechanistic paths to both transition metal and main group element derivatives, e.g., SEi (carbanionic) and oxidative addition (Section II). In thermal decomposition of... 

Several main group metal chalcogenolates can be used as starting materials to obtain other metal chalcogenolate derivatives. 

Fig. 27. Cyclopentadienyl derivatives of some main group metals.

Both the bis-alkyl derivatives, [(Me3Si)2CH]2M (M = Ge, Sn, Pb) and the metallocenes, (CsH5)2M (M = Sn, Pb), function as two-electron donors towards both transition metal and main group metal Lewis acid centres forming complexes of the types [(Me3Si)2CH]2M —>... 

Interaction of metals with cyclopropenylidene to form stable complexes has been widely studied340 in the last two decades since the first reported synthesis of pentacarbonyl(2,3-diphenylcyclopropenylidene)chromium (see belowy4. Two groups of cyclopropenylidene metal derivatives may be distinguished neutral cyclopropenylidene complexes represented by two resonance forms, and the cationic cyclopropenylium transition metal complexes of groups 6 (Cr, Mo, W), 7 (Mn), 8 (Fe) and 10 (Pd, Pt), whereas the latter cationic cr-complexes are derived from both main group metals (Li, Mg) and group 10 (Pd, Pt) transition metals. 

A dimeric proline-derived diamidobinaphthyl dilithium salt has been introduced as the first example of a chiral main group metal-based catalyst for asymmetric hydroami-nation-cyclization reactions of aminoalkenes.256... 

The reactions of type II proceed by transmetallation of the complex 5. The transmetallation of 5 with hard carbon nucleophiles M R (M = main group metals) such as Grignard reagents and metal hydrides MH generates 8. Subsequent reductive elimination gives rise to an allene derivative as the final product. Coupling reactions of terminal alkynes in the presence of Cul belong to Type II. 

Interestingly, radical porphyrin derivatives with oxidation states intermediate between those of [16]-, [18]- and [20]porphyrin are known. In particular, neutral complexes of tetraarylporphyrins with lithium [102] and aluminum [103] were obtained and characterized in the solid state. These complexes of main-group metals are of interest, because the oxidation state of the metal ion is in each case well defined. 

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