A catalyst obtained from rheniecene hydride (η5-C5H5)2ReH at 180–230°C and under a pressure of 10 MPa, is highly active in the hydrogenation of cyclohexene, benzene, and ethyl acetate.

(η5-C5H5)(η3-C5H5)Re− anions are formed in THF as a result of the irreversible two-electron electrochemical reduction of (Cp2Re)2 accompanied by cleavage of the Re-Re bond. The oxidation of these anions leads to the generation of monomeric rhenocene with E0=−1.06 V for the Cp2Re‡0/+ redox transition.

It has been shown that the interaction of bis(cyclopentadienyl)hydridorhenium (Cp/sub 2/ReH, where Cp = eta/sup 5 -/C/sub 5/H/sub 5/) with the halides of zinc, cadmium, beryllium, and magnesium in diethyl ether results in the formation of complex compounds with the general formula Cp/sub 2/ReH MHal/sub 2/. The replacement of ether by tetrahydrofuran in the case of zinc derivatives gives monosolvates with the formula Cp/sub 2/ReH x ZnHal/sub 2/ x THF (Hal = Br, I). On the basis of data from IR and PMR spectroscopy it has been concluded that the bonding of the metal-containing fragments in these complexes is realized either as a result of an Re :..-->.. M donor-acceptor interaction (the complexes with ZnHal/sub 2/ and CdI/sub 2/) or as a result of the formation of a mixed bond (the complexes with BeCl/sub 2/ and MgHal/sub 2/).

The values of the half-wave oxidation potential of the anodic waves of Cp/sub 2/MoH/sub 2/ and Cp/sub 2/ReH indicate that they will be oxidized readily by compounds of transition metal in higher degrees of oxidation (Cu/sup 2 +/, Fe/sup 3 +/, Ti/sup 4 +/, V/sup 4 +/, etc.). In the case of Cp/sub 2/MoH/sub 2/ and Cp/sub 2/ReH the hydrido ligand will be oxidized first, whereas in the case of Cp/sub 2/ReH the course of the oxidation (at the rhenium atom of at the hydrogen atom or at the hydrogen atom) will be determined by the nature of M'L/sub n/. The heterometal complexes based on Cp/sub 2/MoH/sub 2/ and Cp/sub 2/ReH studied are characterized by individual electrochemical behavior and therefore do not dissociate into their components, even in a medium of such a strong base as DMF.

The interaction of bis(eta-cyclopentadienyl)rhenium hydride (rhenocene hydride) with the chlorides and bromides of divalent iron and cobalt has been studied by the methods of IR spectroscopy, magnetochemistry, and x-ray diffraction analysis. It has been established that the reactions of rhenocene hydride with M'X/sub 2/ (M' = Fe, Co; X = Cl, Br) in THF and Te/sub 2/O result in the formation of complexes with the formulas Cp/sub 2/ReH x 2M'Cl/sub 2/ and Cp/sub 2/ReH x M'Br/sub 2/, which have an intermetallic Re ..-->.. M' bond of the donor-acceptor type. The replacement of Et/sub 2/O by acetonitrile causes an ionic compound with the formula ((Cp/sub 2/Re)/sub 2/)/sup 2 +/(CoBr/sub 4/)/sup 2 -/, whose structure was confirmed by x-ray diffraction investigations, to form as a result of the interaction of Cp/sub 2/ReH with CoBr/sub 2/.

AbstractDie Titelverbindung (I).wird durch Reduktion von FeCl3 mit Bis‐[cyclopentadienyll‐rheniumhydrid in THF dargestellt.

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 P1) with the unit cell parameters: a = 10.027(4), b = 10.983(6), c = 10.589(6) Å; α = 116.86(4)°, β = 98.23(4)°, γ = 68.09(4)°, Z = 1, V = 964.7 Å3. Four Fe(II) atoms in the molecule are bonded through the μ3-bridging Cl atoms (Fe-Clav = 2.46 Å), with the coordination sphere of each metal atom being supplemented by the bonding with two or one THF molecule (FeOav = 2.12 Å). 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.

The structure of the bimetallic dimer complex [(η5-C5H5)2Re(H)CuI]2 has been investigated. The crystals are monoclinic: a = 16.070(4) Å, b = 7.788(2)Å, c = 17.439(5) Å; b = 96.62(2)°; the space group I2/a; z = 4. The bond between rhenium and copper atoms (2.60 Å) is of the donor-acceptor type; dimerization occurs by the way of formation of the double bridge CuI2Cu and the direct inter-metal bond CuCu(2.55 Å). The hydride hydrogen atom is the terminal one. The cyclopentadienyl rings form a bent sandwich with the angle between the ring centres and rhenium atom being equal to 158°. It is suggested that the CuCu inter-metal bonding takes place on account of the transition of the non-bonding d-electrons of copper atoms to a high-spin state.

The reduction of copper (II) chloride by molybdenum and rhenium biscyclopentadienyl hydrides upon their interaction in donor-type solvents has been studied by NMR, X-ray diffraction, and magnetic methods. It is established that the ionic complex [(η5-C5H5)2Re]+[CuCl2]− forms ortho rhombic crystals with a - 13.696(2) Å, b = 7.317(1) Å, c = 5.969(1) Å, space group Pm21n, Z = 2. The cyclopentadienyl rings make a bent-sandwich with an angle between the ring centres and Re atom of 150.1°; the ClCuCl angle being 174.8° and the ReCu minimum distance 4.346(29) Å. The solution of [(η5-C5H5)2Re]+ [CuCl2]− seems to activate the CH bond of the C5H5 rings, which results in the addition of the [(C5H5)(C5H4)ReH]+ hydride ion.