Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXIV. Darstellung und Eigenschaften von Tetrabenzylmolybdän und ‐uran

Abstract

Tetrabenzylmolybdän, (C6H5CH2)4Mo, läßt sich durch Umsetzung von Molybdän(IV)‐chlorid‐bis(tetrahydrofuran) mit Dibenzylmagnesium in Form schwarzbrauner, bei Zimmertemperatur beständiger Kristalle gewinnen. Bei der analogen Reaktion von Uran(IV)‐chlorid‐tris(tetrahydrofuran) mit Dibenzylmagnesium entsteht ein rotbrauner Tetrabenzyluran‐Komplex der Formel (C6H5CH2)4U · MgCl2. — Beide Verbindungen werden näher charakterisiert.

In Pursuit of Homoleptic Actinide Alkyl Complexes

“…We suggest that the broadness of the 13 C resonances is due to the fluxional behavior of the benzyl ligand (vide infra). Attempts to probe this behavior with variable-temperature 13 C{ 1 H} NMR spectroscopy were thwarted by the insolubility of 3 in cold THF, which prevents low-temperature spectra from being recorded, and its thermal sensitivity, which prevents hightemperature spectra from being recorded. For example, toluene is observed in a THF-d 8 solution of 3 after only 5 min at room temperature.…”

“…7 Li{ 1 H} NMR (194 MHz, 25 °C, THF-d 8 ): δ 0.50 (s). 13 (3 mL). This resulted in the immediate generation of a paleyellow solution concomitant with the formation of a white precipitate.…”

“…Additionally, the compound reportedly decomposed above 130 °C. 13 Other than elemental analysis, little characterization of this material was provided, but it is likely that the ability of the benzyl ligand to adopt multidentate coordination modes provides enhanced kinetic stability. Similarly, Andersen and co-workers discovered that "UR 4 "-type complexes could be stabilized by the addition of phosphines, 14 which allowed them to isolate the well-characterized complexes AnR 4 (dmpe) n (An = U, Th; R = Me, CH 2 Ph; n = 1, 2).…”

Structure of active centers, their stereospecificity distribution, and multiplicity in diene polymerization initiated by NdCl3‐based catalytic systems

“…The complete replacement of chloride by hydrocarbon radicals in the reaction of f‐metal chloride with organomagnesium compound was disclosed in ref. 6. Actually, the use of dilakylmagnesium Mg(n‐C 4 H 9 )(iso‐C 8 H 17 ) instead of trialkylaluminum in a cis ‐regulating (the content of cis‐units is 93–97%) halide‐containing catalyst NdCl 3 · 3TBP leads to the inversion of its stereospecificity (95% 1,4‐ trans units and 5% 1,2 units7).…”

Kinetic and stereospecific manifestations of a set of active centres in butadiene polymerization under the action of a catalytic system based on NdCl3·3TBP

“…1 Moreover, the examples of the complete replacement of chloride ions with hydrocarbon radicals in reactions of f-element chlorides with organomagnesium compounds are well known. 7,8 The addition of triisobutylaluminium to the NdCl As a result, the occurence of less alkylated forms of active centres such as NdRCl 2 , NdR 2 Cl and their complexes with AlR 3 and MgRR' is possible in the system. Because chlorine atoms occur at centres such as NdRCl 2 and NdR 2 Cl, it is possible to assume that they are cis-regulating.…”