Unusual structural motif in a zwitterionic Fe(II) complex of a tetradentate phosphine

TitleUnusual structural motif in a zwitterionic Fe(II) complex of a tetradentate phosphine
Publication TypeJournal Article
Year of Publication2012
AuthorsJana B, Hovey M, Ellern A, Pestovsky O, Sadow AD, Bakac A
Journal TitleDalton Transactions
Date Published11/7
Type of ArticleArticle
ISBN Number1477-9226
Accession NumberWOS:000309545100019
Keywordsactivation, crystal-structures, diastereomers, ligand, linear tetraphosphine, meso, mononuclear, p-31 nmr, platinum complexes, spin, system

The reaction of meso-DPPEPM (DPPEPM = bis(diphenylphosphino-ethylphenylphosphino)methane) with one equivalent of FeBr2 in tetrahydrofuran generates a zwitterionic compound [FeBr(kappa(2)-DPPEPM)(kappa(3)-DPPEPM-FeBr3)] (1). Compound 1 exhibits an unusual bonding arrangement with two meso-DPPEPM ligands and one bromide coordinated to a single Fe(II) center. One of the DPPEPM ligands binds to iron in a kappa(2) mode via two central phosphorus atoms, leaving the terminal phosphines dangling. The second DPPEPM binds through three phosphines, whereas the fourth one coordinates to the iron center of an external FeBr3- unit. A 1 : 2 reaction of FeBr2 and meso-DPPEPM in tetrahydrofuran generates [FeBr(kappa(2)-DPPEPM)(kappa(3)-DPPEPM)]Br ([2]Br) in which the positive charge on the pseudo-octahedral unit is balanced by free Br- as opposed to the phosphine-bound FeBr3- in 1. The compound [2]PF6 was obtained from [2]Br and TlPF6. Solution structures for 1, [2]Br and [2]PF6 were assigned on the basis of P-31 NMR. For all three compounds the data are consistent with five phosphorus atoms bound to the metal.

URL<Go to ISI>://WOS:000309545100019http://pubs.rsc.org/en/Content/ArticleLanding/2012/DT/c2dt31437ahttp://pubs.rsc.org/en/content/articlepdf/2012/dt/c2dt31437a
Alternate JournalDalton Trans.