Polar Organometallic Precursors to Amido-bridged Transition Metal and Lanthanide Cage Compounds

UoM administered thesis: Phd

  • Authors:
  • Scott Sulway


AbstractThis project involved utilising the Brønsted basic nature of polar organometallic compounds DyCp3 and [Fe{N(SiMe3)2}2], to deprotonate organic compounds that contain an acidic H-N bond to form low co-ordinate compounds that can then aggregate together to form polynuclear cage compounds. Using DyCp3 in a reaction with BtaH, a dimer formed, [(η5-Cp)2Dy(µ-Bta)]2. This dimer is a single-molecule magnet. [(η5-Cp)2Dy(µ-Bta)]2 was compared to a previously reported compound [(η5-Cp)2Dy{µ-N(H)pmMe2}]2 which, despite having a similar structure to [(η5-Cp)2Dy(µ-Bta)]2, is not a SMM. Synthesis of a chlorine- bridged dimer [(η5-Cp)2DyCl(THF)]2 and subsequent magnetic measurements confirmed that [(η5-Cp)2DyCl(THF)]2 is a SMM. Removal of the THF ligand from [(η5-Cp)2DyCl(THF)]2 was achieved via sublimation. The product of this sublimation was a mixture of two different polymorphs of the same compound, [(η5-Cp)2DyCl]2 and [(η5-Cp)2DyCl]infinity. [(η5-Cp)2DyCl]2 was shown to be a SMM, and [(η5-Cp)2DyCl]infinity was shown to display SMM behaviour. [(η5-Cp)2DyCl]infinity had the largest energy barrier to relaxation of magnetisation for any known homospin dysprosium(III) compound. Using [Fe{N(SiMe3)2}2] in a reaction with HppH resulted in the formation of [{Fe{N(SiMe3)2}(hpp)2}2Fe]. [{Fe{N(SiMe3)2}(hpp)2}2Fe] displayed anti-ferromagnetic exchange between the iron(II) centres which resulted in a ground spin state of S = 2. Reacting [Fe{N(SiMe3)2}2] with BtaH resulted in the formation of [{(Me3Si)2NFe}4Fe(Bta)6]. Despite repeated attempts [{(Me3Si)2NFe}4Fe(Bta)6] could not be re-synthesised. An alternative "one pot" synthetic method was attempted, this resulted in the formation of [Fe{N(SiMe3)2}2(LiBta)]2. The structure of [Fe{N(SiMe3)2}2(LiBta)]2 was described using ring-ladder principles and magnetic studies revealed weakly anti-ferromagnetically coupled iron(II) centres which displayed a large zero-field splitting. Extension of the one-pot synthetic route to the use of tin halides was conducted. Using SnCl2 in the one-pot synthetic route resulted in the formation of [{(Me3Si)2N}8Sn8Li8Cl4(Bta)12]. Whilst using SnBr2 resulted in the formation of the compound [{(Me3Si)2N}8Sn8Li8Br4(Bta)12]. The charge separated compound [{(THF)2Li(Bta)}3{Li(THF)}]2[SnI4] was the result of using SnI2 in the one-pot method.


Original languageEnglish
Awarding Institution
  • Richard Layfield (Supervisor)
Award date1 Aug 2012