Deprotonation of 1,4-bis(trimethylsilyI)cyclo-octa-2,5,7-triene affords the 1,4-bis(trimethylsilyI)cyclo-octatetraene dianion, which reacts with [UCI4] or [ThC141 to give the sandwich compoundsand with [ S ~C l ~( t h f ) ~] or [YC13(thf)3] (thf = tetrahydrofuran) to yield [{M(~-C8H~{1,4-(SiMe3)2})(~-C~)}2{thf},], M = Sc, n = 1; M = Y , n = 2; X-ray crystallography shows the latter scandium compound to possess a novel semi-bridging thf ligand. The neutral actinide sandwich compounds, [M(q-C&&], M = U 1 or Th,2 derived from the cyclo-octatetraene dianion, and their anionic lanthanide counterparts, [M(r)-C8H8)2-], M

Lithium or sodium alkoxides MOR (R = CHzCH=CMez; M = Li 1; Na 2; R = C6F5; M = Li 3) were prepared by reaction of the alcohols with n-butyl lithium or sodium metal in hexane. Reaction of a hexane suspension of 3 with SiCIMe 3 afforded SiMe3(OC6F 5) 4, whereas the reaction of 3 equivalents of C6FsOH with AIMe 3 in hexane led to AI (OC6Fs) Alternative methods can also be followed to synthesize 8 and 11. The crystal and molecular structure of 8 has been determined by X-ray diffraction methods. The most interesting feature of this structure is the disposition of the (C6F 5) ring planes, which are located practically on the reflection plane defined by O(1), Zr(1) and O(1)'.

Reaction of PbR2 [R = CH(SiMe3)d with [Ru3-(C0)ld at 60 "C afforded the first ruthenium-lead clusters [Ru3(p-PbR2)(p-CO)dCO)sJ (1) and LRu3(p-PbRZ)z-(p-CO)(CO)g] (2). After separation the compounds were characterized by 'Hand I3C NMR and I R spectroscopies, FAB-MS, and, for 2, by a single-crystal X-ray study. The structure gives the first reported Ru-Pb bond lengths and shows the cluster to have a planar pentametallic array with two PbR2 and one CO bridging the three sides of an Ru3 triangle. A greatly improved yield for the preparation of PbR2 is also reported. -Compound 2 crystallizes i n the triclinic space group P1 with unit cell dimensions a = 12.279(6) A, b = 15.406(6) A, c = 20.775-(5) A, a = 99.54(6)", = 107.47(6)", y = 109.59(6)", U = 3373.1(10) A3, and Z = 2. A total of 10179 unique observations gave a merging R of 0.038 and a conventional R of 0.0756.

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