Tin(II) Ureide Complexes: Synthesis, Structural Chemistry and Evaluation as SnO precursors

Andrew Johnson, James Parish, Michael Hill, K C Molloy, Ibbi Y. Ahmet, Thomas Wildsmith

Research output: Contribution to journalArticlepeer-review

Abstract

In an attempt to tailor precursors for application in the deposition of phase pure SnO we have evaluated a series of tin (1–6) ureide complexes. The complexes were successfully synthesised by employing N,N’-trialkyl‐functionalised ureide ligands, in which features such as stability, volatility, and decomposition could be modified with variation of the substituents on the ureide ligand in an attempt
to find the complex with the ideal electronic, steric or coordinative properties which determine the fate of the final products. All the complexes were characterized by NMR spectroscopy as well as elemental and where applicable thermogravimetric (TG) analysis. The single‐crystal X‐ray diffraction studies of
2, 3, 4 and 6 revealed that the complexes crystalise in the monoclinic space group P2(1)/n (2 and 4) or in the triclinic space group P-1 (3 and 6) as monomers. Reaction with phenyl isocyanate results in the formation of the bimetallic species 5, which crystalises in the triclinic space group P-1, resulting in incomplete insertion into the Sn-NMe2 bonds verses mesityl-isocyanate which produces a monomeric double insertion product, 6, under the same conditions, indicating a difference in reactivity between phenyl-isocyanate and mesityl-isocyanate with respect to insertion into Sn-NMe2 bonds. The metal
centres in these complexes are all four-coordinate, displaying either distorted trigonal bipyramidal or trigonal‐bipyramidal geometries. The steric influence of the imido-ligand substituent has a clear effect on the coordination mode of the ureide ligands, with complexes 2 and 6, which contain the cyclohexyl and mesityl ligands, displaying κ2-O,N coordination modes, whereas κ2-N,N’ coordination modes are observed for the sterically bulkier t-butyl and adamantyl derivatives, 3 and 4. The thermogravimetric analysis of the complexes 3 and 4 exhibited excellent physicochemical properties with clean single‐step curves and low residual masses in their TG analyses suggesting there potential utility of these systems as MOCVD and ALD precursors.
Original languageEnglish
JournalInorganic Chemistry
Publication statusAcceptance date - 12 Oct 2021

Keywords

  • Tin(II)
  • Ureide
  • SnO
  • Precursor
  • AACVD

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