Activation of Ethers and Sulfides by Organolanthanide Hydrides. Molecular Structures of (Cp*2Y)2(.mu.-OCH2CH2O)(THF)2 and (Cp*2Ce)2(.mu.-O)(THF)2

Abstract

Dialkyl ethers, ROR´, are cleaved by hydrides (Cp* 2 LnH) 2 (Ln = Y 1a, La 1b, Ce 1c) to form alkoxides Cp* 2 LnOR (2), Cp* 2 LnOR´, R´H, and RH. The extent to which either of the C-O bonds of asymmetric substituted dialkyl ethers ROR´ is attacked strongly depends on the alkyl substituents but is relatively insensitive to the nature of the metal. Ring opening is observed with THF or 1,4-dioxane leading to Cp* 2 YO n Bu (6a) and (Cp* 2 Y) 2 (µ-OCH 2 CH 2 O)-(THF) 2 (8), respectively. The molecular structure of 8 was determined by X-ray diffraction. Space group Pbcn had unit cell parameters a = 21.7483 (12) Å, b = 14.2806(12) Å, c = 16.726(2) Å and Z = 4. Least-squares refinement based on 4163 reflections converged to R = 0.063. Unsaturated ethers, vinyl ethyl ether and allyl ethyl ether, are cleaved instantaneously by 1a to form Cp* 2 YOEt. Also, the C-O bonds of Cp* 2 LnOEt are attacked by (Cp* 2 LnH) 2 to give the oxo bridged compound (Cp* 2 Ln) 2 (µ-O) and ethane. The molecular structure of the THF adduct of the cerium analogue (Cp* 2 Ce) 2 (µ-O)(THF) 2 (12) was determined by X-ray diffraction: spacegroup P1 had unit cell parameters a = 13.399(2) Å, b = 14.864(4) Å, c = 15.812(6) Å, α = 70.75(2)°, β = 85.15(2)°, γ = 63.78(2)°, and Z = 2. Least-squares refinement based on 6294 reflections converged to R = 0.038. In contrast to ethers, organic sulfides RSRá re metallated by 1a to produce products Cp* 2 YCH 2 SMe (13, R = R´ = Me), Cp* 2 -YCH(SMe)Ph (15, R = Me, R´ = Ph), Cp* 2 Y(SC 4 H 3 ) (18, RR´ = CH=CHCH=CH), and dihydrogen. Only Et 2 S underwent C-S cleavage to form Cp* 2 YSEt (16) and ethane. Reaction of 1a with allyl methyl sulfide is not clean, but 1a is a modest catalyst for the hydrogenation of allyl methyl sulfide. IntroductionOrganometallic compounds of group 3 and lanthanide metals are very active catalysts for polymerization 1 and hydrogenation 2 of olefins. Also, cyclization of 1,4-, 1,5-, and 1,6-dienes is very efficiently catalyzed by scandium and yttrium complexes. 3 However, in general, these catalytic processes have severe limitations, since they can only be performed with nonfunctionalized olefins. Lauke, H.; Mauermann, H.; Swepston, P. N.; Schumann, H.; Marks, T. J. Lauke, H.; Mauermann, H.; Schumann, H.; Marks. T. J. J. Am. Chem. Soc. 1985, 107, 8111. (b) Conticello, V. P.; Brard, L.; Giardello, M. A.; Tsuji, Y.; Sabat, M.; Stern, C. L.; Marks, T. J.

An Alumanylyttrium Complex with an Absorption due to a Transition from the Al−Y Bond to an Unoccupied d‐Orbital

“…[15] In the 13 CNMR spectrum of 2,t he two tetrasubstituted carbon atoms at the a position relative to the Al atom also showed coupling to the Ya tom ( 2 J YC = 6Hz). [16] This value is smaller than that for the directly bonded CH 2 groups to the Yatom ( 1 J YC = 36 Hz). This result clearly indicates that in solution,t he Al atom is directly bondedt ot he Y atom.…”

“…Additionally, a characteristic doublet ( 2 J YH =2.6 Hz) was found for the yttrium‐bonded CH 2 groups at δ H =−0.65 ppm, whose protons are coupled to the 89 Y nuclei (100 % abundance; I = ) . In the 13 C NMR spectrum of 2 , the two tetrasubstituted carbon atoms at the α position relative to the Al atom also showed coupling to the Y atom ( 2 J YC =6 Hz) . This value is smaller than that for the directly bonded CH 2 groups to the Y atom ( 1 J YC =36 Hz).…”

Oxoclusters of the Lanthanides Begin to Resemble Solid-State Materials at Very Small Cluster Sizes: Structure and NIR Emission from Nd(III)

“…For Ln 4 O containing structures in the Cambridge Structural Database, 77 . 42 In addition to four coordinate Ln-oxo structures, there exist an extraordinary range of additional oxo geometries, from the linear or slightly bent Ln-O-Ln found in numerous bimetallic molecules, [22][23][24][25][26] to trigonal planar, pentagonal bipyramidal, and octahedral bonding environments. A coordination number of 2 results when the ancillary ligands inhibit ligand redistribution processes, i.e., in the [Cp* 2 Ln] 2 O compounds, where disproportionation to give Cp* 3 Ln/[Cp*LnO] is energetically unfavorable because of the ligand-ligand repulsions in Cp* 3 Ln.…”

C–H bond activation through steric crowding of normally inert ligands in the sterically crowded gadolinium and yttrium (C 5 Me 5 ) 3 M complexes

“…Calcd. for C 23 82 mmol) were stirred in 40 ml of benzene for 4 h, and the mixture became an intense yellow slurry. The slurry was filtered, and 2 was washed through a frit by using warm benzene because it has low solubility in arenes.…”