Activation of 2,6-Bis(imino)pyridine Iron(II) Chloride Complexes by Methylaluminoxane: An Electrospray Ionization Tandem Mass Spectrometry Investigation

Abstract

The activation of the [2,6-bis(1-((2,6-diisopropylphenyl)imino)ethyl)pyridine]iron(II) chloride complex (1) with methylaluminoxane (MAO) was investigated in tetrahydrofuran (THF) by means of electrospray ionization tandem mass spectrometry (ESI-MS) complemented by UV−visible spectroscopy studies. The four-coordinated cationic methyl iron(II) complex 2 ([LFe-Me]+, L = 2,6-bis(1-((2,6-diisopropylphenyl)imino)ethyl)pyridine) was identified in the ESI-MS experiment. In addition, the cationic monochloride iron(II) complex 3 ([LFe-Cl]+), the product of α-H transfer from 2 to trimethylaluminum (TMA) [LFe-CH2AlMe2]+ (4), and the cationic iron hydride complex 5 ([LFe-H]+) were identified. Correlation of the ESI-MS experiments with UV−visible studies revealed that 2 and 3 are present in the THF solution as their solvent adducts.