G.L. Soloveichik

Structure and magnetic properties of iron(II) chloride tetrahydrofuranate (2FeCl2·3THF)2

Abstract On interacting FeCl3 with Cp2ReH in THF at room temperature while single crystals of the complex (2FeCl2·3THF)2 (I) were obtained. The structure of (I) was established by total X-ray analysis. Crystals of the complex are (space group P 1 ) with the unit cell parameters: a = 10.027(4), b = 10.983(6), c = 10.589(6) A; α = 116.86(4)°, β = 98.23(4)°, γ = 68.09(4)°, Z = 1, V = 964.7 A3. Four Fe(II) atoms in the molecule are bonded through the μ3-bridging Cl atoms (Fe-Clav = 2.46 A), with the coordination sphere of each metal atom being supplemented by the bonding with two or one THF molecule (FeOav = 2.12 A). All the Fe⋯Fe distances in the molecule were non-bonding. The unique magnetic properties of (I) are shown to be specified by the co-existence of ferro- and antiferromagnetic exchange interactions.

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.

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).

Dicyclopentadienyl-yttrium and -aluminium hydridochloride complexes. Crystal and molecular structure of [(η5-C5H5)2Y(μ2-Cl)(μ3-H)Y(η5-C5H5)2](μ2-H)2AlH•NEt3•C6H6: a new type of coordination of the AlH4 moiety

Abstract The interaction of two equivalents of Cp2YCl with one equivalent of LiAlH4 gives the hydride complex (Cp2YH)2(AlH3OEt2)2 (I), described previously, or the hydrido-chloride complexes (Cp2Y)2AlH4Cl · L (L = NEt3 (II), and L = THF (III)). The complexes II and III can also be obtained from the reaction Cp2YCl and AlH3 · L. The X-ray data indicate that complex II is made up of the fragment linked to the AlH3 · NEt3 moiety via two μ2 and μ3 hydrogen atoms, and solvated benzene molecules. On the basis of the IR data complex III is assigned the following structure Cp2Y(μ2-H)2Al(Cl)(μ2-H)2YCp2 · 2THF.

Interaction of tin methylchlorides SnMenCl4−n with molybdenum hydride bis(cyclopentadienyl)

Abstract The interaction between Cp 2 MoH 2 (Cp=η 5 - C 5 H 5 ) and SnMe n Cl 4− n ( n =0−3) proceeds in aprotic solvent with the elimination of HCl and the formation of heterometallic complexes of the composition Cp 2 Mo(H)SnMe n Cl 3− n ( n =0−3) and Cp 2 Mo(SnMe 2 Cl) 2 which contains an MoSn σ-bond. It has been found that in all studied compounds the length of this bond is 0.20–0.30 A less than the sum of the covalent radii of the Mo and Sn atoms. Based on analysis of the geometry of the Mo and Sn environment, the high values of the isomeric shifts ( IS ) in the Mossbauer spectra, the constants of the spin-spin interactions ( SSI ) J 3 Cp-Sn and J 2 HMoSn , and the considerably decreased values of the J 2 Me-sn constants in 1 H NMR spectra, it was concluded that the decrease in the interatomic distance Mo-Sn is due to the high s-character of this bond. It is suggested that this effect, which is most pronounced in wedge-like complexes, is brought about by changing the orbital hybridization type of the tin atom from sp 3 to s + 3p. This can explain the shorter interatomic distance M-Sn in heterometallic complexes of other types.

Structural chemistry of titanium and aluminium bimetallic hydride complexes: VIII. Crystal and molecular structures of the complex (η5-C5H5)2Ti(η2-H)2Al(CH3)(μ2-H)2Ti(η5-C5H5)2, an effective catalyst for olefin hydrogenation, and its decomposition product, [(η5-C5H5)2Ti(η2-H)2Al(η2-H)-(η1:η5-C5H4) Ti(η5-C5H5)(μ2-H)]2 · C6H6

Abstract Reactions of (Cp 2 Ti) 2 AlH 4 Cl and (Cp 2 Ti) 2 AlH 4 BH 4 (Cp = η 5 -C 5 H 5 ) with LiCH 3 and LiAl(CH 3 ) 4 in ether or in an ether/benzene mixture yield a trinuclear complex Cp 2 Ti(μ 2 -H) 2 Al(CH 3 )(μ 2 -H) 2 TiCp 2 , which crystallizes in a rhombic lattice with unit cell parameters a 8.405(1), b 21.349(3), c 22.337(3) A, space group F2dd , Z = 8. The compound is unstable and decomposes in solution to give a new modification of a hexanuclear complex [Cp 2 Ti(μ 2 -H) 2 Al(μ 2 -H)(η 1 : η 5 -C 5 H 4 )TiCp(μ 2 -H)] 2 with unit cell parameters a 11.354(2), b 23.360(3), c 16.062(3) A, γ 94.07(3)°, space group P 2 1 / n , Z = 4. The instability of (Cp 2 Ti) 2 AlH 4 Me is accounted for by an increase in the electron density on metal atom nuclei on coordination of the methyl group. For the same reason elevated catalytic activity of this compound in the reactions of hexene-1, homogeneoys hydrogenation (180 mol H 2 /g-atom Ti min) and isomerization (11.8 mol C 6 H 12 /g-atom Ti min) is observed.

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.

An intramolecular secondary ClSn bond; Crystal and molecular structure of (η5-C5H5)2Mo[(CH3)2SnCl]2

Abstract The structure of the trimetallic complex (η5-C5H5)2Mo[(CH3)2SnCl]2 (I) was determined by X-ray analysis. Crystals of I are monoclinic: a 30.519(6), b 13.953(2), c 9.082(2) A, γ 106.50(1)°, space group P21/n, Z=8, ϱcalcd 2.13 g/cm3. The structure of I consists of two independent, isolated Cp2Mo(Me2SnCl)2 molecules containing MoSn σ-bonds of different lengths (2.740 and 2.706 A for Ia; 2.733 and 2.717 A for Ib). The inequivalence of the MoSn distances within the molecule appears to be accounted for by the formation of a secondary intramolecular Sn(1)ClSn(2) bond (r(Sn---Sn) 3.616 A, r(Cl---Sn(2)) 2.89 A). The coordination around the Sn(2) atom is distorted trigonal bipyramidal, while that around the Sn(1) atom is distorted tetrahedral. The considerable contraction of the MoSn interatomic distances (against the sum of the covalent radii of the metals) is assumed to be determined by the increased s-contribution of the bond in question.

Bis(cyclopentadienyl) molybdenum complexes containing MoSn σ-bond

Abstract The reactions of Cp 2 MoH 2 with SnCl 2 with SnCl 4 ·5H 2 O and with SnCl 4 have been studied. Elimination of HCI and five water molecules has been shown to take place in the case of SnCl 4·5H 2 O and the product Cp 2 Mo(H)SnCl 3 (1) formed. In the other case the substance [Cp[in2 Mo(H)SnCl 3 ] 2 SnCl 4 (II) formed as a result of the reaction of Cp 2 MoH 2 with SnCl 4 . It can be treated as the products of Lewis base-acid reaction (I) with SnCl 4 . The substances (I) and (II) were investigated by H n.m.r., 119 Sn Mossbauer and i.r. spectroscopy methods. On the basis of the spectroscopic data, the structures of (I) and (II) have been suggested. The existence of terminal hydride in the solid state is characteristic for (I), while the bridge bond MoHSn occurs in the solution. In the (II) strong (MoH→) 2 Sn bonding takes place in the condensed phase, and the distruction of the complex (II) during dissolving is observed.

Kinetically stable adduct of samarocene with aluminium deuteride (η-C5H3tBu2)2Sm(μ2-D)2AID·Me2NC2H4NMe2

Abstract The interaction of (C5H3tBu2)2Sm·THF with AlD3 in ether in the presence of TMEDA yields compounds of composition (C5H3tBu2)2SmAlD3·TMEDA (I). Metal atoms are bonded by the double bridge SmD2Al. The coordination polyhedron of Al in I is a trigonal bipyramid. Stability of this substance to redox reaction occurring in the Cp2″Sm·THF-AlD3 system can be explained by the isotopic kinetic effect.