Isonitriles metal complexes

The isonitrile metal complexes can be synthesized by reactions of isonitriles with metal carbonyls (substitution reactions) or, more rarely, by alkylation of metal-... 

A60. J. P. Candlin, K. A. Taylor, and D. T. Thompson, "Reactions of Transition-Metal Complexes. Elsevier, Amsterdam, 1968. A review of types of reactions of metal complexes (e.g., substitution, combination, redox) reactions with various reagents (e.g., hydrocarbons, halides, carbon monoxide, and isonitrile) and preparation of new stabilised organic systems (e.g., metallocenes, carbenes). Intended for research workers, consequently written at a fairly high level, with emphasis on organometallics. A61. H. J. Keller, NMR-Untersuchungen an Komplexverbindungen. Springer, Berlin, 1970. Expansion of review article 37.1. 

Multicomponent condensations have also been described in these an isonitrile, a carbonyl compound and a suitable transition metal complex are combined in one step to afford heterocycloalkylidene complexes. Examples of the use of isolated or intermediate isonitrile complexes for the preparation of aminocarbene complexes are given in Table 2.4. 

Table 1. Typical Reactions of Metal Complexes with Isonitriles ...

Treatment of alkylating agents with metal cyanides should in principle be the method of choice for preparing isocyanides (equation 25). But as the cyanide ion again represents an ambident nucleophile, the well-known problems already discussed will arise (Section 1.8.2.1.i). It remains to be stated that simple alkylation of alkali metal cyanides with halogen compounds or dialkyl sulfates is not useful for the preparation of isonitriles. The formation of nitriles always prevails and isocyanides are at best obtained in yields of up to 25%. " The prospects are much tetter in the alkylation of heavy metal cyanides, if the reaction is done under conditions which initially give rise to isocyanide-transition metal complexes (equation 26). These will then be transformed into isonitriles by treatment with KCN. Under optimized conditions this technique yielded 55% of ethyl isocyanide. ... 

In 1988 Lalor reported the synthesis and spectroscopic characterization of some new poly(benzo-triazolyl)borate salts (Scheme 8).180 The regiospecifity of the synthesis of I I B( Btz)4 differs from that of pyrazole/BH4 reaction in that B—N bond formation takes place in a manner that maximizes steric crowding at boron (i.e., at the triazole N(l) atoms). In 1989 Shiu describes some new metal carbonyls of HB(Btz)3.181 The synthesis and spectroscopic characterization of some first-row transition metal complexes was reported by Cecchi,182 whereas Hill described some new Rh183 and Ru184 carbonyl and isonitrile complexes. The formation of isonitrile derivatives was proposed to proceed through an associative mechanism involving an intermediate complex... 

Two general type of processes that proceed by way of a putative enolate-metal complex have been documented (1) those in which the metaiioenoiate nucleophile is generated following deprotonation of C-H acid 257—>258, and (2) those in which the metaiioenoiate is generated upon desilylative metallation of an enol silane 261—>262 (Scheme 21). Examples of the former processes have been documented and utilize activated C-H acids with pK (H2O)<20 such as isonitrile esters 259, nitroalkanes 260, and ketones. Fewer cases have been reported for the catalytic addition of enol silanes through a putative metaiioenoiate intermedi-... 

Reactive monomeric species of RNBR composition can be isolated by trapping at low temperatures. The monomers are prepared by low-pressure thermal degradation of boranamines or azidoboranes L Cyclization reactions can occur on warming to RT. In the absence of steric hindrance, trimeric borazine rings invariably form, but with sufficiently bulky substituents (e.g., R = R = t-Bu), dimeric species result. However, even with nonbulky substituents many monomers can form cyclic dimers at low temperature if subjected to catalysis by certain transition-metal complexes or the isonitrile t-BuNC... 

Carbodiimides. Palladium(II) chloride, primary amines, and isonitriles form a carbene—metal complex (1), which on treatment with silver oxide is converted into a carbodiimide (2) in yields of 75-95%. Actually, the complex... 

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