Gas-phase study of new organozinc reagents by IRMPD-spectroscopy, computational modelling and tandem-MS

TitleGas-phase study of new organozinc reagents by IRMPD-spectroscopy, computational modelling and tandem-MS
Publication TypeJournal Article
Year of Publication2011
AuthorsA.R Massah, F. Dreiocker, R.FW Jackson, B.T Pickup, J. Oomens, A Meijer, M. Schafer
JournalPhysical Chemistry Chemical Physics
Volume13
Number29
Pagination13255-13267
Type of ArticleArticle
ISBN Number1463-9076
Accession NumberWOS:000292981600016
KeywordsAMINO-ACIDS, CROSS-COUPLING REACTIONS, ELECTROSPRAY-IONIZATION, INFRARED-SPECTROSCOPY, MASS-SPECTROMETRY, ORGANIC-SYNTHESIS, PHOTON DISSOCIATION SPECTROSCOPY, vibrational spectroscopy, ZINC(II) COMPLEXES, ZWITTERION STABILITY
Abstract

An extensive set of organozinc iodides, useful for Negishi-type cross-coupling reactions, are investigated as respective cations after formal loss of iodide in the gas phase. Firstly, two new alkylzinc compounds derived from Tyrosine (Tyr) and Tryptophan (Trp) are closely examined. Secondly, the influence of specific protecting groups on the subtle balance between intra-and intermolecular coordination of zinc in these reagents is probed through trifluoroacetyl (TFA)-derivatized alkylzinc compounds. Finally, the influence of the strongly coordinating bidentate ligand N,N,N',N'-tetramethylethylenediamine (TMEDA) on the structure of alkylzinc cations is further explored in order to better understand the stability of the respective complexes towards water. A combination of electrospray (ESI)-MS/MS, accurate ion mass measurements, infrared multiple-photon dissociation (IRMPD) spectroscopy and computational modelling allowed the full characterisation of all dimethylformamide (DMF)-solvated and TMEDA-coordinated alkylzinc cations in the gas phase. The calculations indicate that the zinc cation in gas-phase alkylzinc-DMF or TMEDA-complex ions preferentially adopts a tetrahedral coordination sphere with four ligands. Additionally, conformers with only three binding partners bound to zinc but with effectively combined hydrogen-bond interactions are also found. Collision induced dissociation (CID) patterns demonstrate that the zinc-DMF interaction in tetrahedral four-coordinate mono-DMF-zinc complex ions as well as the interaction between TMEDA and zinc in the corresponding complex ions is even stronger than typical covalent bonds. In most cases, all major features of the IRMPD spectra are consistent with only a single major isomer, allowing secured identification and assignment.

URL<Go to ISI>://WOS:000292981600016
Division

GUTHz

Department

Molecular Dynamics

PID

cd85b13fe4f248ef083eb41ac14c270d

Alternate TitlePhys. Chem. Chem. Phys.

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