Redox-Active Behavior of the [{Ti(η⁵-C₅Me₅)(μ-NH)}₃(μ₃-N)] Metalloligand

Abstract

Treatment of [Cl3Y{(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)}] with [K(C5Me5)] in toluene gives C10Me10 and the paramagnetic [K(μ-Cl)3Y{(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)}] (3) derivative. Crystallization of 3 in pyridine affords the potassium-free [Cl2(py)2Y{(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)}] (4) complex. Whereas the reaction of 3 with 1 equiv of 18-crown-6 leads to the molecular complex [(18-crown-6)K(μ-Cl)3Y{(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)}] (5), the analogous treatment of 3 with cryptand-222 affords the ion pair [K(crypt-222)][Cl3Y{(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)}] (6). The X-ray crystal structures of 4, 5, and 6 have been determined. Density functional theory (DFT) calculations have elucidated the electronic structure of these species, which should be regarded as containing trivalent Y bonded to the {(μ3-NH)3Ti3(η(5)-C5Me5)3(μ3-N)} metalloligand radical anion.

Homo and heteropolymetallic Group 4 molecular nitrides

“…and broad resonances in the 1 H NMR spectra of complexes 14-16 compare well with that found  = 11.1-10.2 for equivalents  5 -C5Me5 ligands in yttrium complexes with the oneelectron reduced radical metalloligand {(3-NH)3Ti3( 5 -C5Me5)3(3-N)}. 22 The magnetic moment measurements by the Evans method gave eff = 2.01 B for 15 and eff = 1.95 B for 16 confirming their paramagnetic nature with an unpaired electron.…”

“…Most likely, the additional electron is delocalized among the three titanium atoms of the metalloligand in a fashion similar to that determined by DFT calculations for the analogous yttrium/titanium anion [Cl 3 Y{(μ 3 -NH) 3 Ti 3 (η 5 -C 5 Me 5 ) 3 (μ 3 -N)}] − . 22 The reduced species 14 retains one potassium cation as part of the structure according to analytical data and presumably has a polymeric structure. Despite considerable efforts we could not grow suitable crystals of 14 for an X-ray crystal structure determination and its reaction with macrocyclic polyethers was examined (Scheme 5).…”

“…Further indication of the versatility of the titanium metalloligand is the capacity of 1 to accept one electron delocalized among the three titanium atoms to form a radical anion as observed in the reaction of [Cl3Y{(3-6 NH)3Ti3( 5 -C5Me5)3(3-N)}] with [K(C5Me5)]. 22 As part of this program, we sought to prepare chloride complexes of the early transition-metals stabilized by metalloligands derived from 1 and to explore their use as starting materials for new organometallic derivatives. Herein we report the synthesis, structure, and properties of a series of Group 4 chloride complexes x(3-NH)3-xTi3( 5 -C5Me5)3(3-N)}] (M = Ti, Zr, Hf).…”

Heterometallic Cube‐Type Molecular Nitrides

“…[80] Analogous treatment of 1 with bis(cyclopentadienyl) derivatives ). [81] This species exhibits far-downfield and very broad resonances in the 1 H NMR spectrum and is paramagnetic, with one unpaired electron, according to magnetic moment measurements by the Evans method. This result, along with the exclusive formation of C10Me10 as byproduct, formed via coupling of pentamethylcyclopentadienyl radicals, suggests that the reaction pathway consists in an electron transfer from the C5Me5anion to the yttrium-titanium cube-type complex Adapted from the original report.…”

“…This result, along with the exclusive formation of C10Me10 as byproduct, formed via coupling of pentamethylcyclopentadienyl radicals, suggests that the reaction pathway consists in an electron transfer from the C5Me5anion to the yttrium-titanium cube-type complex Adapted from the original report. [81]…”