Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

TitleSynthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines
Publication TypeJournal Article
Year of Publication2011
AuthorsJana B, Ellern A, Pestovsky O, Sadow A, Bakac A
Journal TitleInorganic Chemistry
Date Published04/04
ISBN Number0020-1669
Accession NumberISI:000288730400042
Keywordsbis(diphosphine) complexes, c-h bonds, catalysts, crystal-structures, GEOMETRY, iron(ii), ligand, p-31 nmr, stereochemical control, STRUCTURAL-CHARACTERIZATION

rac-Bis[{(diphenylphosphino)ethyl}-phenylphosphino]methane (DPPEPM) reacts with iron(H) and ruthenium(II) halides to generate. complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl-2 (1) in CD2Cl2 features sa tridentate binding mode as established by P-31{H-1} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br-2 (2) revealed a pseudo-octahedral, cis-alpha geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD2Cl2 solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru-(K-4-DPPEPM)Cl-2 (3) is obtained from rac-DPPEPM and either [RuCl2(COD)](2) [COD = 1,5-cyclooctadiene] or RuCl2-(PPh3)(4). The structure of 3 in both the solid state and in CD2Cl2 solution features a folded K-4-DPPEPM. This binding mode was also observed in cis-[Fe(K-4-DPPEPM)(CH3CN)(2)](CF3SO3)(2) (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yield cis-[Fe(k(4)-DPPEPM)Cl(CO)] (Cl) (5). The same reaction in CH2Cl2 produces a mixture of 5 and [Fe(K-3-DPPEPM)Cl-2,(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of k(4)-DPPEPM.

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Alternate JournalInorg ChemInorg Chem