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J. Am. Chem. SOC.1981,103, 6508-6510
which form a second divalent complex which contains much less soluble divalent products of this reaction would be expected to hydride (by deuteriolysis) and a smaller percentage of samarium.26 be highly reactive. A preliminary survey of reactivity supports This latter divalent product can be purified, however, by a subthis contention. The crystallized product reacts rapidly with CO, sequent low temperature THF recrystallization to provide purple, NO, 3-hexyne, HgR2, and C O ( P R ~to) ~form trivalent products. crystalline (C5Me5)2Sm(THF)2(I), identified by a n a l y t i ~ a l , ~ ~ It is also observed to polymerize ethene and functions as a catalyst magnetic?7 infrared,” and X-ray diffraction methods. Since this precursor for catalytic hydrogenation of 3-hexyne to >99% cisreaction can be conveniently run to provide a recrystallized yield 3-hexene under mild condition^.^^ These reaction products, as of 0.5 g of I,28 this metal vapor synthesis provides the first well as the interesting byproducts of this metal vapor reaction, preparative scale route to a soluble divalent organosamarium are currently under investigation. On the basis of these results, complex.29 we anticipate a rich and varied reaction chemistry for divalent I is not only the first soluble divalent organosamarium complex organosamarium complexes now that a preparative scale synthesis but also the first structurally characterized divalent organoof a soluble derivative is available. samarium system. Two crystallographically independent molecules Acknowledgment. We thank the National Science Foundation are found in the unit cellmand do not differ significantly in bonding for support of this research and the Camille and Henry Dreyfus parameters. Figure 1 presents a view of one of the molecules. Foundation for a Teacher-Scholar Grant (to W.J.E.). Average Sm-C($) and Sm-0 bond lengths are 2.86 (3) and 2.63 (1) A, respectively. In comparison, (C5Me5)2Yb(THF)(C7HE)0.510 Supplementary Material Available: Tables of bond distances, has Yb-C(q5) and Yb-0 distances of 2.66 and 2.41 %I, respecbond angles, final fractional coordinates, and thermal parameters tively. The differences in these distances, 0.20 and 0.22 A, are and the ORTEP plot of the other crystallographically independent only slightly larger than the difference in ionic radii of Sm(I1) molecule of (C5Me5)2Sm(THF)2in the unit cell (31 pages). and Yb(II), 0.1831-0.19.32 The small lengthening can be atOrdering information is given on any current masthead page. tributed to the more crowded coordination environment in the disolvated 8-coordinate samarium case. (37) At 25 OC and 1 atm of H,, the rate was 0.85 X lo-) turnovers/min The ’H NMR spectrum of 133in C&, the first reported NMR based on H2 uptake. spectrum of a divalent samarium complex, exhibited relatively sharp singlets at 6 2.45 (30 H, A Y ~=, ~8 Hz) and 4.43 (7 H, Aul = 33 Hz) and a broad absorption at 6 17.99 ( A Y ~ =, ~92 Hzj. Exchange of the solvated THF in I with THF-d8gave a complex which displayed only the 6 2.45 absorption. Hence, we assign this absorption to C5Me5,the 6 4.32 absorption to the @-CHIgroup A Novel Catalytic System for Homogeneous most distant from the Sm(I1) center, and the broad resonance Hydrogenation of Carbon Monoxide: Ruthenium to the a-CH2 group. The I3C N M R spectrum of 134in C6D6 Complexes in the Presence of Iodide Promoters exhibited a pattern of absorptions just the opposite of that found in other pentamethylcyclopentadienyl lanthanide complexes:35 6 I B. Duane Dombek -73.7 (s, C5(CH3)5), 33.4 (t, J = 125 Hz, OCH2CH2CHZCHz), , Union Carbide Corporation 94.62 (9,J = 117 Hz, CS(CHJs), 149.5 (OCH2CH2CH2CH2).36 South Charleston, West Virginia 25303 Given the large radial size and large reduction potential of Sm(I1) compared to the other accessible divalent lanthanides, the Received July 6, 1981
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(26) Crystallization from THF at -78 “C gives purple crystals which Homogeneous catalysts for CO hydrogenation and systems contain ca. 29%Sm rather than the 35% found in the original THF extract. modeling their b e h a ~ i o rhave ~ . ~ been the subject of much recent Deuteriolysis gives HD to D2 ratios of 1:l rather than 2:l. If this product is research because such catalytic systems offer the potential of dissolved in THF and subsequently reanalyzed, the % Sm drops to ca. 27 [cf. selectively converting synthesis gas to chemicals now derived from (CsMeS)2Sm(THF)2,26.61%]and the HD to D, ratio falls to
