Titanium η¹-Pyrrolyl Complexes:  Electronic and Structural Characteristics Imposed by the N,N-Di(pyrrolyl-α-methyl)-N-methylamine (dpma) Ligand

Abstract

A new tridentate pyrrolyl-based ligand (dpma) has been utilized in the syntheses of two unusual titanium complexes. The trigonal bipyramidal species allow direct structural comparison between dialkylamido, pyrrolyl, and amine ligands within the same coordination sphere. Pyrrolyl ligands have greatly reduced π-donating ability relative to dialkylamides, which leads to Ti−N(pyrrolyl) distances that are ∼0.14 Å longer than the dimethylamido substituents. Reduced π-donation relative to dialkylamido by the pyrrolyl substituents seems to result in enhanced Lewis acidity for dpma derivatives.

Substituted quinolines as noncovalent proteasome inhibitors

“…The ancillary ligands for titanium H 2 dpma and H 2 dpm are both prepared in a single step from pyrrole. 44–46 The catalysts for this study were isolated as pure compounds before use; however, it is possible to generate the catalysts in situ from the protio-ligand and commercially available Ti(NMe 2 ) 4 as well. 40 The applications of these two catalysts in iminoamination have been discussed elsewhere in detail.…”

“…Ti(NMe 2 ) 2 dpma and Ti (NMe 2 ) 2 dpm were made following the literature procedures. 44–46 Ti(NMe 2 ) 2 dpm was used for all of the quinolines synthesized, with the exceptions 31 and 32 in which Ti(NMe 2 ) 2 dpma was used. tert -Butylisonitrile was made according to the literature procedure 54 and purified by distillation under dry nitrogen but it may also be purchased from Sigma Aldrich.…”

Titanium catalyzed one-pot multicomponent coupling reactions for direct access to substituted pyrimidines

“…For this study, two pyrrole-based titanium catalysts, Ti(dpma)(NMe 2 ) 2 14 (1) and Ti(dpm)(NMe 2 ) 2 15 (2), were employed. Both these catalysts can be synthesized in a single step in almost quantitative yield by reacting commercially available Ti(NMe 2 ) 4 with H 2 dpma or H 2 dpm (Scheme 2).…”

Manganese Complexes of Pyrrole‐ and ­Indolecarboxamide Ligands: Synthesis, Structure, Electrochemistry, and Applications in Oxidative and Lewis‐Acid‐­Assisted Catalysis

“…Intriguingly, pyrrole and indole moieties, despite having importance in anion recognition, [87][88][89][90][91] have been scarcely used as far as their coordination chemistry is concerned. [92][93][94][95][96][97][98][99] In electron paramagnetic resonance spectroscopy. All complexes functioned as catalysts in olefin epoxidation reactions by using PhIO as the oxo-transfer agent.…”