# Synthesis and Reactivity of Lewis-Base-Supported Terminal Thorium Imido Metallocene, (η5‑C5Me5)2ThN(p‑tolyl)(dmap)2

## TL;DR

Scientists synthesized a thorium imido metallocene and found it can participate in various chemical reactions, including cycloadditions and deprotonation.

## Contribution

The synthesis and reactivity of a Lewis base-supported terminal thorium imido metallocene are reported, showcasing diverse chemical transformations.

## Key findings

- The thorium imido metallocene undergoes multiple cycloaddition reactions with sulfur, selenium, alkynes, and other organic compounds.
- The imido group acts as a nucleophile toward metal halides, esters, and azidosilanes.
- Substituent effects on ligands influence the reactivity of thorium imido metallocenes.

## Abstract

Treatment of (η5-C5Me5)2ThMe2 (1) with p-tolylNH2 in toluene, in the presence of 4-dimethylaminopyridine
(dmap),
affords a Lewis base-supported terminal thorium imido metallocene,
(η5-C5Me5)2ThN­(p-tolyl)­(dmap)2 (5), alongside the
release of methane. In toluene solution, an equilibrium is established
among complex 5, dmap, and the amido pyridyl complex
(η5-C5Me5)2Th­[NH­(p-tolyl)]­[κ2-C,N-4-(Me2N)­C5H3N] (5′), setting the stage for diverse reactivity. Complex 5 may initiate [2 + 2], [2 + 4], [2 + 1], or [2 + 3] cycloadditions
with elemental sulfur and selenium, alkynes, carbodiimides, ketones,
thio-ketones, isothiocyanates, CS2, organic nitriles and
isonitriles, as well as organic azides. Moreover, imido moiety can
act as a nucleophile toward metal halides, esters, and azidosilanes;
and it may promote deprotonation reactions with 1-methylimidazole,
2,6-Me2C5H3NO, Me3PO,
silanes, amidate PhCONH­(p-tolyl), and nitriles (PhCH2CN and Ph2CHCN). Notably, reaction of 5 with Me3SiCHN2 forms the bimetallic complex
[(η5-C5Me5)2Th]2(μ-NNNCSiMe3)2 (44) with toluene elimination. In contrast, complex 5′ undergoes reactions with elemental selenium and
tellurium, PhSiH2Cl, organic isonitriles (2,6-Me2C6H3NC, Me3CNC, and C6H11NC), and organic azides (p-tolylN3 and Ph3CN3) to afford amido selenido,
amido tellurido, chloro pyridyl, amido pyridyl, amido alkenyl, and
bis-amido complexes, respectively. Furthermore, a comparison with
related terminal imido thorium metallocenes illustrates how substituent
effects on the cyclopentadienyl and imido ligands influence the reactivity
of these molecules.