A.I. Sizov

Dicyclopentadienylsamarium complexes with t-butyl substituents in the ring. Crystal and molecular structures of the solvate (η5-C5H3Bu2t)2Sm · OC4H8 and homoleptic ate complex [NaSm(η5:η2-C5H4But)3 · OC4H8]n

Abstract Interaction of SmI 2 with C 5 H 3 Bu 2 t Na and C 5 H 4 Bu t Na yielded a monosolvate (I) with the formula (η 5 -C 5 H 3 Bu 2 t ) 2 Sm · OC 4 H 8 and a homoleptic ate complex (II) with the formula [NaSm(η 5 :η 2 -C 5 H 4 Bu t ) 3 · OC 4 H 8 ] n . The crystals of I are monoclinic: a 11.449(3); b 15.305(4); c 17.688(5) A; γ 92.93(2)°; space group P 2 1 / n ; Z = 4; d calcd 1.24 g/cm 3 . This compound is monomeric with a pseudotrigonal coordination environment around the Sm atom. The crystals of II are rhombic: a 8.969(2); b 15.964(4); c 21.701(5) A; space group Pc 2/ n ; d calcd 1.30 g/cm 3 . The lattice of II is built up of planar polymer grids between which crystallizational THF molecules are located.

The crystal and molecular structure of the 20-electron alumohydride complex of bis(t-butylcyclopentadienyl)samarium {[(η5-C5H4But)2Sm(μ3-H)][(μ2-H)2AlH·OC4H8]}2

Abstract The reaction of one equivalent of the samarium(II) Na[(C5H4But)3Sm]·THF complex with 2 equivalents of AlH3 in THF oxidises the samarium and gives the SmIII complex {[(η5-C5H4But)2Sm(μ3-H)][(μ2-H)2AlH·OC4H8]}2 (I). Crystals of I are triclinic, a 10.030(1), b 13.328(2), c 10.349(1) A, α 109.36(1), β 115.27(1), γ 89.45(1)°, space group P 1 , Z = 2, ϱ(calcd) 1.42 g/cm3. Samarium is coordinated by four hydrides and has a formal 20e configuration. The coordination polyhedron of Al is a trigonal bipyramid.

Isomerization of olefins on hydride-halide compounds of titanium and aluminium of composition LmTiH2AlXX′. The role of the cocatalyst and the geometry of the ligand environment of the titanium atom in catalytic hydrogen transfer

Abstract Using bimetallic complexes of the compositions (C 5 H 5 ) 2 TiH 2 MXX′ and (CH 2 ) n (C 5 H 4 ) 2 TiH 2 AlXX′ (M = B, Al; X,X′ = H,Hal, Alk, n = 1–3) as examples, the rate of homogeneous catalytic isomerization of α-olefins has been studied under the influence of the ligand environment, the nature of the transition metal, and the substituent at M. Only titanium and aluminium complexes with non-rigid ligand environments and involving terminal AlH bonds show catalytic activity in the reaction. An alkyl isomerization mechanism at the heterobinuclear centre is suggested. The first reaction step involves coordination of an olefin at the six-coordinate Al atom followed by the insertion of the olefin molecule in the terminal AlH bond.

Ytterbium(+2) indenyl complexes: synthesis and crystal structures of (C9H7)2Yb·DME, rac-(CH2)2(1-C9H6)2Yb(THF)2, and rac-(CH2)2[1-(4,7-(CH3)2C9H4)]Yb(THF)2

Abstract Metallation of 2,2-bis(1′-indene)propane by sodium hydride followed by the reaction of the sodium derivative with YbCl3 yields (C9H7)2Yb·DME (1), an ytterbium(+2) complex with unlinked indenyl ligands. The reaction between (CH2)2(1-Ind′)2Li2 and YbCl3 in diethyl ether with subsequent reduction of the product by sodium metal in THF gives rac-(CH2)2(1-Ind′)2Yb(THF)2, where Ind′=C9H6 (2) and 4,7-(CH3)2C9H4 (3). The structures of the complexes were determined by X-ray structural analysis.

Copper(I) complexes with metal-metal (d10–d10) bond. Crystal and molecular structures of adducts of tantalocene trihydride with copper(I) iodide of composition: (η5-C5H5)2TaH[(μ2-H)Cu(μ2-I)2Cu(μ2-H)]2HTa(η5-C5H5)2, (η5-C5H4But)2TaH(μ2-H)2Cu(μ2-I)2Cu(μ2-H)2HTa(η5-C5H4But)2·CH3CN and {Cu(μ3-I)·P[N(CH3)2]3}4

Abstract An interaction of copper(I) halogenides with tantalocene trihydride Cp′2TaH3 led to adducts of 2:1 (Cp = η5-C5H5) or 1:1 (Cp′ = C5H5But) composition. Structures of complexes (η5-C5H5)2TaH[(μ2-H)Cu(μ2-I)2Cu(μ2-H)]2TaH(η5-C5H5) (I) and (η5-C5H4But)2TaH(μ2-H)2Cu(μ2-I)Cu(μ2-H)2TaH(η5-C5H4But)2 (III) were established by X-ray analysis. Crystals of I are monoclinic: a = 8.010, b = 11.032, c = 16.613 A, γ = 105.1°, space group I2/m, Z = 2, R = 0.20. Crystals of III are monoclinic: a = 16.378(4), b = 16.968(4), c = 16.607(4) A, γ = 113.57(3)°, space group P21/b, Z = 4, R = 0.031 (Rw = 0.031). In both complexes the Cu(μ2-I)2Cu moiety is bonded with tantalum atoms by one (I, Ta …. Cu = 2.788 A) or two (III, Cu….Cu = 2.844 A) hydrogen bridges. rhombs are not planar owing to the formation of the direct intermetal bonds between Cu(I) atoms (Cu….Cu distance is equal to 2.602 A for I and 2.913 A for III). The model of bonding in LnCu(μ2-I)2CuLn complexes has been proposed and the conditions of realization of the bond between transition metal atoms with a d10 electron shell are discussed. It is shown that the conditions of n = 2 and bulky ligand L are essential but insufficient, e.g. the 1:1 adduct of Cu(I) with bulky phosphine P(NMe2)3 is a tetramer [Cu(μ3-I)·P(NMe2)3]4 (V) without CuCu bonds. Crystals of V are monoclinic: a = 14.695(5), b = 14.999(5), c = 23.406(8) A, space group P21/n, Z = 4, R = 0.039 (Rw = 0.040).

Alane complexes of divalent ytterbocenes. Bimetallic mechanism of styrene polymerization

Abstract Heterometallic complexes of divalent ytterbocenes Cp′ 2 Yb (Cp′ = ( tert -Bu) 2 C 5 H 3 , C 5 Me 5 ) and alanes AlH 3 · L (L = NEt 3 , C 4 H 8 O, Et 2 O) have been obtained without changing the oxidation state of the lanthanide atom. The complexes Cp′ 2 YbAlH 3 · L have been shown to be moderately active for styrene polymerization, producing atactic polystyrene. Linear olefins have not been incorporated in the polymerization process. The results provide some evidence for the heterometallic mechanism of styrene polymerization.

Synthesis, structure and properties of divalent bis(di-tert-butylcyclopentadienyl)ytterbium complexes with diethyl ether and 1,2-dimethoxyethane

Abstract The reaction between YbI2 and 1,3-tBu2C5H3Na containing some 1,2-tBu2C5H3Na in diethyl ether or 1,2-dimethoxyethane afforded (1,3-tBu2C5H3)2Yb·OEt2 (1), (1,3-tBu2C5H3)2Yb·DME (2) and (1,2-tBu2C5H3)2Yb·DME (2a). The crystal structures of 1 and 2a were determined. Crystals of 1 are monoclinic: a=11.302(2) A, b=19.018(4) A, c=14.404(3) A, β=90.41(3)°, dcalc=1.291 g cm−3, space group P21/n, z=4. Mean bond distances Yb–C, Yb–O and the bond angle Cp–Yb–Cp are 2.69(2) A, 2.430(14) A, and 133.0°, respectively. Crystals of 2a are monoclinic: a=13.782(3) A, b=10.299(2) A, c=10.849(2) A, β=95.04(3)°, dcalc=1.337 g cm−3, space group C2, z=2. Mean bond distances Yb–C, Yb–O and the bond angle Cp–Yb–Cp are 2.72(2) A, 2.53(2) A, and 143.2°, respectively. The ether-free complex (1,3-tBu2C5H3)2Yb (3) displays low catalytic activity in the polymerization of ethene.

Structural chemistry of titanium and aluminium bimetallic hydride complexes: VII. Exchange reactions in the coordination sphere of aluminium atom. Crystal and molecular structure of [(η5-C5H5)2Ti(μ2-H)2]2Al(η2-H2B of [(η5-C5H5)2Ti(μ2-H)2]2Al(η2-H2BH2)☆

Abstract The interaction of Cp2TiH2AlH(Cl), Cp2TiH2AlCl2, and (Cp2ti)AlH4Cl (Cp = η5-C5H5) with LiBH4 in ether yields a four-nuclear complex (Cp2Ti(μ2-H)22)-Al(μ2-H)2BH2 in 70-80% yields. The compound forms rhombic crystals: a 9.515(3), b 9.449(3), c 22.051(4) A, space group Pnab, V 1982 A, Z = 4, ϱcalc 1.35 g/cm3. The enlargement of the hydride complexes of aluminium and titanocene to three- and four-nuclear compounds is the result of the dissociation in solution of the bi-nuclear complexes to give the corresponding A1XX′2 alanes. This led to us to revise the 17-component ESR spectrum of the complex Cp2TiH2AlHCl, and it was concluded that this spectrum is a superposition of the signals of Cp2TiH2AlCl2 and Cp2TiH2 Al1HCl, and perhaps of Cp2TiH2AlH2 (the singlet of (Cp2Ti)2AlH4Cl, which is also present in solution does not affect the general picture of the spectrum). The specific rate of hydrogenation of hexene-1 on (Cp2Ti)Alh4(BH4) is 10 Mol H2/g-atom Ti min.

Structural chemistry of titanium and aluminium bimetallic hydride complexes VI. Molecular structure and physico-chemical properties of (η5-C5 H5) 2Ti(μ2-H)2 Al(Cl) (μ2 -H)2Ti(η5-C5H 5)2, a catalyst-precursor for hydrogenation in the [(η5-C5H5)2TiCl]2-LiAIH4 system ☆

Abstract The complex (Cp 2 Ti) 2 AlH 4 Cl has been isolated from the catalytic system (Cp 2 TiCl) 2 -LiAlH 4 , which is a precursor of the catalyst for the hydrogenation and isomerization of olefins. This complex has been studied by X-ray diffraction. The complex forms rhomboidal crystals with unit cell dimensions a = 10.414, b = 11.998, c = 16.008 A, space group P 2 1 2 1 2 1 , Z = 4, and density ϱ calc = 1.40 g/cm 3 . The Cp 2 Ti moieties are linked to the Al atom via double hydrogen bridges; the Cl atom is bonded to the Al atom. Analysis of the EPR spectral data and some chemical properties of (Cp 2 Ti) 2 AlH 4 Cl solutions has led us to suggest a mechanism for the formation of the catalytically active species upon interaction of this compound with olefins and solvating solvents.

Aluminium zirconium (+3 and +4) heterometallic hydrido complexes of compositions [(η5-C5H5)2Zr(μ-H)]2(μ-H)AlCl2 and [(η5-C5H5)2ZrH(μ-H)2]3Al

Abstract The Zr(+3) complex of composition [Cp2Zr(μ-H)]2(μ-H)AlCl2 (8) and the Zr(+4) complex of composition [Cp2ZrH(μ-H)2]3Al (9) were isolated from solutions containing zirconocene(+4) and titanocene(+3) compounds and LiAlH4 and characterized by X-ray structural analysis. The basic structural element of 8 is the six-atom ring Zr2AlH3, in which the metal atoms are linked by ordinary hydrogen bridges. In the structure of 9, the Hbendo atom is off the bisector plane of the Cp2Zr fragment and the Al–H distances in the distorted octahedral environment of the aluminium atom are markedly different.