Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes.

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^iPr)(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^iPr)(η⁵-Cp)(Cl)₂] and [M(PNP^iPr)(I)₃], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNP^iPr)(Me)₃]. Upon treatment of [Ti(NMe₂)₄] with [P(NH)P-iPr] a complex with the general formula [Ti(PNP^iPr)(NMe₂)₃] is obtained. DFT calculations revealed that the most stable species is [Ti(κ¹N- PNP^iPr)(NMe₂)₃] featuring a κ¹N-bound PNP ligand. When [P(NH)P-iPr] is reacted with [Ti(NMe₂)₄] in CH₂Cl₂ complex [Ti(PNP^iPr)(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^iPr)(Br)₄][H₂NMe₂]. The corresponding hafnium complex [Hf(PNP^iPr)(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.

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Supplementary information

The online version contains supplementary material available at 10.1007/s00706-024-03171-x.

SUBMITTER: Tomsu G 

PROVIDER: S-EPMC10908616 | biostudies-literature | 2024

REPOSITORIES: biostudies-literature