INVESTIGATIONS OF POLYMERIZATION AND METATHESIS REACTIONS .21. REACTIONS OF ALKYL ISOTHIOCYANATES WITH THE CARBYNE TUNGSTEN(VI) COMPLEX CL3(DME)W-EQUIVALENT-TO-C(T)BU

Reactions of alkylisothiocyanates RN=C=S (R = Et, (n)Bu, Cy) with the Schock type carbyne complex Cl3(dme)W=O(t)Bu yield insoluble, polymeric products. Solid state C-13-NMR, IR and elemental analysis indicate equimolar reactions of the carbyne complex with the alkylisothiocyanates. The reaction product of n-butylisothiocyanate and the carbyne complex was extracted with n-pentane, which was not carefully dried. In this way crystals of partially hydrolyzed, tetrameric units were formed in the pentane extract. The X-ray structure analysis of these crystals revealed that the monomeric unit is a compound with a tungstena-thiazolidine ring. Asymmetric oxo bridges link four octahedrally coordinated tungsten centers to form tetramers. In the unhydrolyzed, polymeric reaction products chloro bridges may link the tungsten centres. A postulated reaction pathway involves a metathesis-like reaction of the isothiocyanates with Cl3(dme)W=C(t)Bu to give imido tungsten complexes. A proton shift to the nitrogen yields Mannich bases. These form tungstena thiazolidine derivatives by ring closure reactions.