Targeted Synthesis of End-On Dinitrogen-Bridged Lanthanide Metallocenes and Their Reactivity as Divalent Synthons.

High-yield syntheses of the lanthanide dinitrogen complexes [(CpM)(μ-1,2-N)] (, M = Gd, Tb, Dy; Cp = 1,2,4-CBuH), in which the [N] ligands solely adopt the rare end-on or 1,2-bridging mode, are reported. The bulk of the -butyl substituents and the smaller radii of gadolinium, terbium, and dysprosium preclude formation of the side-on dinitrogen bonding mode on steric grounds. Elongation of the nitrogen-nitrogen bond relative to N is observed in , and their Raman spectra show a major absorption consistent with N═N double bonds.

Structural and Magnetization Dynamics of Borohydride-Bridged Rare-Earth Metallocenium Cations.

The structure and magnetic properties of the bimetallic borohydride-bridged dysprosocenium compound [{(η-Cp)(η-Cp)Dy}(μ:κ:κ-BH)][B(CF)] ([][B(CF)]) are reported along with the solution-phase dynamics of the isostructural yttrium and lutetium analogues (Cp is 1,2,4-tri(-butyl)cyclopentadienyl, Cp is tetramethyl(-butyl)cyclopentadienyl). The synthesis of [][B(CF)] was accomplished in the 2:1 stoichiometric reactions of [(η-Cp)(η-Cp)Dy(BH)] () with [CPh][B(CF)], with the metallocenes obtained from reactions of the half-sandwich complexes [(η-Cp)M(BH)(THF)] () (M = Y, Dy, Lu) with NaCp. Crystallographic studies show significant lengthening of the M···B distance on moving through the series , , and , with essentially linear {M···B···M} bridges in .