SYNTHESIS AND PROPERTIES OF ORGANOMETALLIC RINGS AND MACROCYCLES CONTAINING FERROCENE, SILICON, AND UNSATURATED HYDROCARBON UNITS - X-RAY CRYSTAL-STRUCTURES OF THE NOVEL FERROCENOPHANES FE(ETA-C5H4)2(SIME2)2(CH=CH) AND TRANS,TRANS-FE(ETA-C5H4)2(SIME2)2(CH2CH=CHCH2)2

A range of novel cyclic organometallic compounds containing ferrocene, silicon, and unsaturated hydrocarbon units have been synthesized and characterized. These species were prepared via the insertion of alkynes or butadiene into the silicon bond of the ferrocenyldisilane Fe(eta-C5H4)2(SiMe2)2 (1). Thus, the reaction of 1 with the acetylenes HC=CH and HC=CPh in the presence of Pd(PPh3)4 catalyst in toluene at 110-degrees-C yielded the organometallic ring products Fe(eta-C5H4)2(SiMe2)2(RC=CR') (2, R = R' = H, 3, R = H, R' = Ph). Reaction of 1 with MeO2CC=CCO2Me under the same conditions yielded mainly the monoinsertion product Fe(eta-C5H4)2(SiMe2)2(RC=CR) (4; R = CO2Me) together with trace amounts of the diinsertion product Fe(eta-C5H4)2(SiMe2)2(RC=CR)2 (5; R = CO2Me). Significant quantities of the acetylene cyclotrimerization derivative C6(CO2Me)6 (6) were also formed. By contrast, reaction of 1 with butadiene under the same conditions exclusively yielded the macrocyclic diinsertion product Fe(eta-C5H4)2(SiMe2)2-(CH2CH=CHCH2)2 (7). Characterization of the latter by C-13, Si-29, and H-1 NMR spectroscopy indicated the presence of an approximate 7:3 mixture of the trans,trans and cis,trans isomers. The X-ray crystal structures of 2 and trans,trans-7 were determined. Crystals of 2 are monoclinic, space group P2(1)/n, with a = 6.3131 (8) angstrom, b = 15.7160 (12) angstrom, c = 16.8650 (22) angstrom, beta = 95.087 (11)-degrees, V = 1666.7 (3) angstrom3, and Z = 4. Crystals of 7 are orthorhombic, space group Pcnb, with a = 11.188 (4) angstrom, b = 13.530 (5) angstrom, c = 14.654 (8) angstrom, V = 2218 (2) angstrom3, and Z = 4.