Pentacarbonyl(tetrafluoroborato)rhenium setzt sich mit Trimethyl(1‐propinyl)stannan zu (OC)5Re–CC–CH3 (1), mit Ethinyltrimethylsilan zum σ,π‐Ethinid‐verbrückten Komplex [(OC)5Re(μ‐η1,η2‐CCH)Re(CO)5]+ BF–4 (2) um. Aus 2 und Natriumethanolat entsteht unter HBF4‐Abspaltung der σ,σ‐Ethindiid‐verbrückte Komplex (OC)5Re–CC–Re(CO)5 (3). 3 läßt sich mit HBF4·Et2O wieder zu 2 protonieren.

Abstract The cycloaddition of nitriles and of dimethylacetylenedicarboxylate to the azide ligand of polymeric Schiff Base cobalt(III) and phosphine palladium(II) complexes gives the corresponding tetrazolate and triazolate complexes from which the heterocycles could be cleaved by hydrogen chloride. Usually the yields are low; if the heterocycle is soluble in ether or sublimable, yields up to 30% have been obtained. Using this method the hitherto unknown 5-trichlormethyltetrazole could be prepared which was characterized by an X-ray structural analysis. Similarly, the cyclo-addition of azido(tetraphenylporphinato)cobalt(III) with nitriles, cyclohexylisocyanide and MeO2CC≡CCO2 Me affords the corresponding complexes with heterocyclic ligands. The prepa-ration of tetraphenylporphyrinato(tricyanmethanido)cobalt(III), (TPP)CoN=CC(CN)2 , is reported.

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195 ChemInform Abstract The cycloaddition of nitriles (II) and (V) or the alkyne (VII) with the azide function of the polymeric Co complex (Ia) affords Co-heterocycle complexes of type (III), giving the free tetrazoles (IV), (VI) and triazole (VIII) on cleavage with HCl. Yields are generally low, however, if the product is neither sublimable nor soluble in ether. The above procedure gives access to the trichloromethyl derivative (IVa) (X-ray analysis: space group P21/c with Z=4; previous syntheses had failed because of the formation of explosive intermediates). Alternatively, the target heterocycles can be prepared by treatment of nitriles or (VII) with the complexes (Ib), (XI) (obtained from Merrifield's resin (IX)) or (XIII). The reaction of the latter with the isocyanide (XIV) gives the product (XV) containing a Co-C bond.