Premium
Microsolvated and Chelated Butylzinc Cations: Formation, Relative Stability, and Unimolecular Gas‐Phase Chemistry
Author(s) -
Fleckenstein Julia E.,
Koszinowski Konrad
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200901963
Subject(s) - chemistry , iodide , acetonitrile , denticity , solvent , medicinal chemistry , tetrahydrofuran , dimethoxyethane , nucleophile , inorganic chemistry , reactivity (psychology) , ligand (biochemistry) , chelation , electrospray ionization , organic chemistry , ion , metal , medicine , biochemistry , alternative medicine , receptor , electrode , pathology , electrolyte , catalysis
Solutions of butylzinc iodide in tetrahydrofuran, acetonitrile, and N , N ‐dimethylformamide were analyzed by electrospray ionization mass spectrometry. In all cases, microsolvated butylzinc cations [ZnBu(solvent) n ] + , n =1–3, were detected. The parallel observation of the butylzincate anion [ZnBuI 2 ] − suggests that these ions result from disproportionation of neutral butylzinc iodide in solution. In the presence of simple bidentate ligands (1,2‐dimethoxyethane, N , N ‐dimethyl‐2‐methoxyethylamine, and N , N , N′ , N′ ‐tetramethylethylenediamine), chelate complexes of the type [ZnBu(ligand)] + form quite readily. The relative stabilities of these complexes were probed by competition experiments and analysis of their unimolecular gas‐phase reactivity. Fragmentation of mass‐selected [ZnBu(ligand)] + leads to the elimination of butene and formation of [ZnH(ligand)] + . In marked contrast, the microsolvated cations [ZnBu(solvent) n ] + lose the attached solvent molecules upon gas‐phase fragmentation to produce bare [ZnBu] + , which subsequently dissociates into [C 4 H 9 ] + and Zn. This difference in reactivity resembles the situation in organozinc solution chemistry, in which chelating ligands are needed to activate dialkylzinc compounds for the nucleophilic addition to aldehydes.