CESIUM ALKYLSILYLAMIDES

Cesium mono(trimethylsilyl)amide [CsNH(SiMe3)]4

      Cesium mono(trimethylsilylamide) [CsNH(SiMe3)]4 was synthesized and characterized. [[i]] Its structure was determined to be tetrameric [CsNH(SiMe3)]4. It was synthesized by the reaction of metallic cesium with NH(SiMe3)2 in an NH3/Fe(NO3)3*9H2O mixture; desylilation of silylamide was probably caused by the presence of hydrated Fe salt. [CsNH(SiMe3)]4may be potentially applicable as Cs or Cs-N precursor for MOCVD or ALD of Cs-containing thin films.

[i] M. Lappert, Ph. Power, A. Protchenko, A. Seeber, Metal Amide Chemistry, 2009

Cesium bis(trimethylsilyl)amide [CsN(SiMe3)2]2

    Cesium bis(trimethylsilylamide) [CsN(SiMe3)2]2  was synthesized by direct reaction of metallic cesium with hexamethyldisilazane NH(SiMe3)2. It was structurally characterized and was shown to have dimeric structure [CsN(SiMe3)2]2  (see M. Lappert et al.) [i].

    Another way of synthesis of [CsN(SiMe3)2]2   (or CsHMDS), not using pyrophoric Cs metal or Cs organometallic reagents was reported: reaction of  cesium fluoride CsF with an equimolar amount of lithium bis(trimethylsilyl)amide LiN(SiMe3)2 dissolved in n-hexane produced  CsHMDS in 80% yield (after sublimation).[ii]

     [CsN(SiMe3)2]2 is sublimable and thus potentially applicable as Cs precursor for MOCVD or ALD of Cs-containing thin films.

[i] M. Lappert, Ph. Power, A. Protchenko, A. Seeber, Metal Amide Chemistry, 2009

[ii] A.I. Ojeda-Amador, A.J. Martínez-Martínez, A.R. Kennedy, Ch.T. O’Hara, Inorg. Chem. 2016, 55, 11, 5719-5728, doi.org/10.1021/acs.inorgchem.6b00839, https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.6b00839#, « Structural Studies of Cesium, Lithium/Cesium, and Sodium/Cesium Bis(trimethylsilyl)amide (HMDS) Complexes » 

Cesium bis(trimethylsilyl)amide tris[2-(2-methoxy ethoxy)ethyl]amine adduct Cs[N(SiMe3)2](TMEAA)

Fig. Molecular structure of CsN(SiMe3)2(TMEAA)

    Reaction of dimer [CsN(SiMe3)2]2 with tris[2-(2-methoxyethoxy)ethyl]amine (TMEEA) yielded monomeric [CsN(SiMe3)2 (TMEAA)]. This complex was characterized by by multinuclear NMR spectroscopy in solution and X-ray crystallography; the molecular structure is depicted in Fig. [i]

   Due to monomeric nature, the complex may have some volatility and be potentially applicable as Cs precursor for MOCVD or ALD.

[i] A.I. Ojeda-Amador, A.J. Martínez-Martínez, A.R. Kennedy, Ch.T. O’Hara, Inorg. Chem. 2016, 55, 11, 5719-5728, doi.org/10.1021/acs.inorgchem.6b00839, https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.6b00839#, « Structural Studies of Cesium, Lithium/Cesium, and Sodium/Cesium Bis(trimethylsilyl)amide (HMDS) Complexes »  

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