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ChemInform Abstract The reaction of the Sm compound (I) with an excess of AlMe3 (II) yields the binuclear title complex (III). THF cleaves the bridging AlMe4 units in (III) liberating AlMe3 and the mononuclear title complex (V). The structures of (III) (space group P21/n, Z=2) and (V) (Pnma, Z=4) are determined by X-ray analysis. (V) reacts with aromatic and aliphatic hydrocarbons including benzene, toluene, hexane, cyclohexanes, cyclooctane liberating methane via net activation of C-H bonds. With toluene e.g. the benzyl derivative (VII) is formed. The methane generated in the reactions of (V) with deuterated substrates is CH4, which suggests that intramolecular formation of a spectroscopically undetected intermediate containing a metalated C5Me5 ring may occur before intermolecular reaction with the C-H bond. (V) metalates pyridine-d5 to form CH3D, reacts with Et2O to give the ethoxo derivative of (V), and reacts with H2 to form ((C5Me5)2Sm(µ-H))2. Both (III) and (V) polymerize ethylene.

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Synthesis and Reactivity of the Cationic Organosamarium(III) Complex [(C5Me5)2Sm(THF)2][BPh4], Including the Synthesis and Structure of a Metallocene with an Alkoxy-Tethered C5Me5 Ring, (C5Me,)2Sm[0(CH2)4C5Me5](THF)1

CSMeS)2Sm (1) and (C5Me5)2Sm(THF)2 (2) isomerize cis-stilbene to trans-stilbene. The stoichiometric reaction of 1 with stilbene forms [(C5Me5)2Sm]2(p-q2:~4-PhCHCHPh) (3). 1 reacts with styrene to form [(C5Me5)2Sm]2(p-v2:q4-CH2CHPh) (4). In both 3 and 4, the two (C5MeS)2Sm units coordinate on opposite sides of the alkene bond such that the Sm-Sm vector bisects the bond at right angles. In each complex, phenyl carbon atoms are oriented to interact with one of the samarium centers. In 4, the Sm-C(CSMe5) distances range from 2.678 (18) to 2.847 (18) A, the Sm-C(alkene) distances range from 2.537 (15) to 2.732 (15) A, and two carbon atoms of the phenyl ring are positioned 2.772 (17) and 2.850 (16) A from one samarium atom. 3 crystallizes from hexane in space group P2,2,2 with a = 12.156 ( 6 ) A, b = 14.405 (9) A, c = 15.628 (2) A, and V = 2737 (2) A' with Z = 2 for DmId = 1.24 g cm-'. 4 crystallizes from hexane in space group Pbca with a = 21.169 (4) A, b = 17.663 (3) A, c = 23.713 ( 5 ) A, and V = 8866 (3) .A3 with Z = 8 for Dded = 1.417 g cm-'.Least-squares refinement of the model based on 3134 observed reflections converged to a final RF = 6.2%.The coordination chemistry of the lanthanides with unsaturated substrates has developed rapidly in recent years and has shown that earlier assessments of the bonding capacity of these metals were inaccurate. In the past, it was thought that neutral hydrocarbons and other nonpolar substrates would not interact extensively with these metals due to the limited radial extension of their 4f valence orbitals and the concomitant highly ionic character of the bonding. However, crystallographically characterized lanthanide complexes are now known which contain (a) +arene ligands, e.g., Sm(s6-C6Me6)(r12-Aic14)31 and Gd($-C6H3B~*3)2,2 (b) $-alkyne ligands, e.g., (C5Me5)zYb(q2-MeC= CMe)3 and [(C5MeS)zSm]2(p-d:$-Ph2C4)," (c) metal-coordinated

272ChemInform Abstract The title compound (I) react with excess of cyclopentadiene (II) to form the η5-cyclopentadienyl-Sm(III) derivative (III). This is also obtained from the THF diadduct of (I) in similar way (yield 98%). With a deficiency of (II), (I) forms the mixed-valence complex (IV) which is also produced from (III) and (I) by 1:1 molar reaction. The structures of (III) (space group P21/n, Z=4) and (IV) (P1, Z=2) are confirmed by X-ray analysis. In (IV), the bis(pentamethylcyclopentadienyl)-Sm(II) unit coordinates to two C atoms of the cyclopentadienyl ring in the trivalent (C5Me5)2Sm(C5H5) part of the molecule.