Halogen complexes Heavy metals

The block copolymer of ethylene oxide and 3,3-dimethylthietane shows useful properties of complexing halogen and heavy metal salts (79MI51402). Thietanes can be polymerized with methylmagnesium iodide as well as with a variety of electrophiles such as methyl sulfate, trimethyloxonium tetrafluoroborate, triethylaluminum, boron trifluoride and phosphorus trifluoride (67IC1461, 67MI51400). Thietane (210) has been patented as a stabilizer for poly(vinyl chloride) (73USP3767615). 

The synthesis of pentacarbonyl rhenium(I) halides, Re(CO)5X, succeeded from simple and complex rhenium halides below 200 atm of CO at 200° C. The compounds are extraordinarily stable and form easily, often quantitatively, from carbon monoxide and rhenium metal in the presence of other heavy metal halides or halogen sources such as CC14. Later we prepared the corresponding carbonyl halides of manganese (67) and technetium (68) from their respective carbonyls. It was found that the corresponding binuclear tetracarbonyl halides [M(CO)4X]2 (M = Mn, Re) could be made by heating the mononuclear M(CO)5X complexes (15, 69), as well as by other methods. 

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. ... 

Piperidine. Hexahydropyridine. CjH N mol wt 85.15. C 70.52%, H 13.02%, N 16.45%. Found in small quantities in Piper nigrum L.. Piperaceae (black pepper). May be obtained from pipeline by henting with alcoholic KOH, or from 1,5-diaminopentane hydrochloride by cycli-zarion. Usually prepd by electrolytic reduction of pyridine. Forms complexes with salts of heavy metals. Because of its reactivity, piperidine is useful in the prepn of cryst derivatives of aromatic nitro compds contg nuclear halogen atoms Seikel, J, Am. Chem. Soc. 62, 750 (1940). Review of physical constants of piperidine and N-alkyl piperidines Magnus -... 

Using a somewhat different approach, Fischer and Fichtel (85) have obtained a variety of ethylene-containing cationic complexes by reaction of TT-cyclopentadienyl carbonyl halides of Mo, W, and Fe with ethylene under pressure in the presence of aluminum chloride. The cations were isolated in the form of their salts with heavy anions such as PFe , B(C6H5)4, etc. Presumably the aluminum chloride serves as a halogen acceptor and activates a coordination site on the metal, facilitating coordination of ethylene. 

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