Syntheses and some reactions of complexes containing carbon chains capped by ferrocenyl and W(CO)3CP groups

The preparation and some reactions of W{(C dropC)(n)}(CO)Cp [n = 1-4 (1-4)] are described. For n = 1 and 2, Cu(I)-catalysed reactions between Fc(C dropC)(n)H (n = 1, 2) and WCl(CO)(3)CP gave compounds 1 and 2, respectively, while Cu(I)-Pd(0)-catalysed coupling between FcC drop CI and W(C drop CC drop CH)(CO)(3)Cp gave 3. Oxidative coupling of FcC drop CC drop CH and W(C drop CC drop CH)(CO)(3)Cp gave 4, together with both homo-coupled products. Electrochemical studies showed that the Fc/Fc(+) oxidation potential increases by about 50 mV for each C dropC triple bond added to the carbon chain. Reactions with Co-2(mu -dppm)(m)(CO)(8-2m) (m = 0, 1) gave complexes 6-10 in which the Co, fragment is attached to the sterically least-hindered C dropC triple bond. The novel vinylidene cluster Co2W(mu (3)-CCPhFc)(mu (3)-PPhCH2PPh2)(CO)(5)Cp (5) was also obtained from 1 and Co-2(mu -dppm)(CO)(6). Reactions of 1 with tetracyanoethene (tene) gave the cyclobutenyl (11) and buta-1,3-dien-2-yl (12) complexes by cycloaddition to the CMC triple bond and subsequent ring-opening. In the presence of silica gel, 12 reacts with MeOH to give the chelating imino complex W{C[=C(CN)(2)C(OMe)=NH]CFc=C(CN)(2)}(CO)(2)Cp (13). With 2 and 3, addition of tcne to the C dropC triple bond one removed from the tungsten centre gave buta-1,3-dien-2-yl complexes 14 and 15. X-ray crystal structure determinations have been carried out on 2, 5, 7, 8 and 10-14. (C) 2001 Elsevier Science B.V. All rights reserved.