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Synthesis and Hydrolysis–Condensation Study of Water-Soluble Self-Assembled Pentacoordinate Polysilylamides

DOI: 10.1021/om301137b DOI Help

Authors: Muhammad Sohail (The Open University) , Alan R. Bassindale (The Open University) , Peter Taylor (Open University) , Alexander A. Korlyukov (A.N. Nesmeyanov Institute of Organoelement Compounds (INEOS), Russian Academy of Sciences) , Dmitry E. Arkhipov (A.N. Nesmeyanov Institute of Organoelement Compounds (INEOS), Russian Academy of Sciences) , Louise Male (University of Southampton) , Simon Coles (University of Southampton) , Michael B. Hursthouse (University of Southampton) , Ross W. Harrington (Newcastle University) , William Clegg (Newcastle University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Organometallics , VOL 32 (6) , PAGES 1721-1731 and 2874

State: Published (Approved)
Published: May 2013
Diamond Proposal Number(s): 987

Abstract: Polysilylamides (n = 1–8) with a Si–Cl functionality containing pentacoordinate silicon in the backbone were produced in high yield by transsilylation of bis(chloromethyl)methylchlorosilane and the trimethylsilyl derivative of diketopiperazine. Pentacoordinate polysilylamides were highly soluble in water as a result of silicon water coordination (Si←OH2) from hydrolysis of the Si–Cl group in each repeat unit. Interestingly, the water silicon coordination in polysilanolamides was stable toward self-condensation and found to contain pentacoordinate silicon even in water, thus avoiding siloxane (Si–O–Si) bond formation. In the gas phase the polysilanolamides underwent intramolecular stepwise hydrolysis–condensation possibly as a result of C═C double-bond formation at each monomer unit, as observed by MALDI-TOF MS. Low-intensity peaks of macrocyclic polysilanolamides (n = 2–5) were also observed that contain water molecules. For a better understanding of the hydrolysis–condensation process of the polysilylamide, new model compounds of pentacoordinated silicon derivatives of pyridones were synthesized, characterized, and compared with the polysilanolamides using NMR and X-ray crystallography. X-ray analysis of the model compounds revealed insight into the silicon water coordination in each repeat unit and the mode of packing within the polymers that contain these monomer units. It is found that the partial hydrolysis of the model pentacoordinate chlorosilanes gives water-coordinated pentacoordinate silicon species that resemble an intermediate in the aqueous hydrolysis of pentacoordinate polysilylamides.

Subject Areas: Chemistry, Materials


Instruments: I19-Small Molecule Single Crystal Diffraction

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