Synthesis, characterization, and electrochemistry of a series of iron (ii) complexes containing self-assembled 1,5-diaza-3,7-diphosphabicyclo[3.3.1]nonane ligands

Andrew D. Burrows, Ross W. Harrington, Andrew S. Kirk, Mary F. Mahon, Frank Marken, John E. Warren, Michael K. Whittlesey

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The reaction between PPh(CH2OH)2, iron(II) sulfate, ammonium sulfate, and formaldehyde in aqueous solution gives the iron(II) complex [Fe(κ2-O2SO2)L2] (1), where L is the bidentate phosphine ligand 3,7-diphenyl-1,5-diaza-3, 7-diphosphabicyclo[3.3.1]nonane. During the course of the reaction, the ligand L self-assembles on the metal center. The reaction between PPh(CH 2OH)2, iron(II) chloride, ammonium chloride, and formaldehyde under similar conditions gives cis-[FeCl2L2] (cis-2). The complex cis-2 is converted into trans-2 In Et2O, whereas in water it is converted into cis-[Fe(OH2)2L 2]2+, though both of these interconversions are reversible. The chloro ligands in cis-2 are readily displaced by reaction with thiocyanate, azide, and carbonate to give cis- and trans-[Fe(NCS) 2L2] (cis- and trans-3), cis- and trans-[Fe(N 3)2L2] (cis- and trans-4), and [Fe(κ2-O2CO)L2] (5), respectively. The complex cis-2 reacts with CO in water to give trans-[FeCl(CO)L2]Cl (trans-6), whereas trans-2 reacts with CO in diethyl ether to give cis-[FeCl(CO)L2]Cl (cis-6), though cis-6 isomerizes in water to form trans-6. The reaction of cis-2 with sodium borohydride gives the hydride chloride complex trans-[FeCl(H)L2] (7). Electrochemical studies have been undertaken on complexes 1, cis-2, and 7. These reveal reversible oxidations for cis-2 and 7, with the latter giving rise to an unusual 17-electron iron(III) hydride chloride complex. Crystal structures have been obtained for 1, trans-2, trans-2,5, and 7. © 2009 American Chemical Society.
    Original languageEnglish
    Pages (from-to)9924-9935
    Number of pages11
    JournalInorganic Chemistry: including bioinorganic chemistry
    Volume48
    Issue number20
    DOIs
    Publication statusPublished - 2009

    Fingerprint

    Dive into the research topics of 'Synthesis, characterization, and electrochemistry of a series of iron (ii) complexes containing self-assembled 1,5-diaza-3,7-diphosphabicyclo[3.3.1]nonane ligands'. Together they form a unique fingerprint.

    Cite this