Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes
Gerald Tomsu1, Berthold Stöger2, Karl Kirchner1
1Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, 1060 Vienna, Austria.
Abstract:
The synthesis, characterization, and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH2 linkers to two phosphine donors is described. Treatment of [P(NH)P-iPr] with [MCl4(THF)2] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNP)(μ-Cl)(Cl)2]2 featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe3I to give the mononuclear complexes [M(PNP)(η5-Cp)(Cl)2] and [M(PNP)(I)3], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNP)(Me)3]. Upon treatment of [Ti(NMe2)4] with [P(NH)P-iPr] a complex with the general formula [Ti(PNP)(NMe2)3] is obtained. DFT calculations revealed that the most stable species is [Ti(κ1N- PNP)(NMe2)3] featuring a κ1N-bound PNP ligand. When [P(NH)P-iPr] is reacted with [Ti(NMe2)4] in CH2Cl2 complex [Ti(PNP)(Cl)2(NMe2)] is formed. Treatment of a solution of [P(NH)P-iPr] and [Zr(NMe2)4] with SiMe3Br affords the anionic seven-coordinate tetrabromo complex [Zr(PNP)(Br)4][H2NMe2]. The corresponding hafnium complex [Hf(PNP)(Br)4][H2NEt2] is obtained in similar fashion by utilizing [Hf(NEt2)4] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography.
Supplementary Information:
The online version contains supplementary material available at 10.1007/s00706-024-03171-x.
More Related Videos
07:20Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
14:11Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Related Concept Videos
Five-Membered Heterocyclic Aromatic Compounds: Overview
Basicity of Heterocyclic Aromatic Amines
Valence Bond Theory
Chirality at Nitrogen, Phosphorus, and Sulfur
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
¹H NMR: Pople Notation
A proton...
Nucleophilic Aromatic Substitution: Addition–Elimination (SNAr)
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between...
