Poly(alkyl/aryloxothiazenes): inorganic polymers with a sulfur(VI)-nitrogen backbone. Synthesis, characterization, and theoretical calculations

• Published in: Journal of the American Chemical Society Vol. 115; no. 7; pp. 2604 - 2612
• Main Authors: Roy, Aroop K, Burns, Gary T, Lie, George C, Grigoras, Stelian
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.04.1993; Amer Chemical Soc
• Subjects: Applied sciences; Chemistry; Chemistry, Multidisciplinary; Exact sciences and technology; Inorganic and organomineral polymers; Physical Sciences; Physicochemistry of polymers; Preparation; Science & Technology; NITROGEN; PHOSPHORUS; ATOMS; MACROMOLECULES; PRECURSORS; POLY(ALKYL/ARYLPHOSPHAZENES); Polysilane; Condensation polymerization; Sulfonamide; Organometallic polymer
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00060a009

N-Silylsulfonimidates [Me3SiN=S(O)(R1)OR2,3] with appropriate R2 groups have been found to undergo thermally induced condensation to produce the sulfur(VI)-nitrogen backbone polymers poly(alkyl-or aryloxothiazenes), [N=S(O)R1]n 4 and 5. Polymers 4 and 5 represent the first alkyloxothiazene polymers and the first characterized aryloxothiazene polymers. Modeled after the well-known condensation of N-silylphosphoranimines to poly(phosphazenes), the polycondensation of 3 to 4 appears to be a fairly general reaction. The design and novel synthesis of 3 are described in a companion article. The thermal condensation of 3 is catalyzed by Lewis acids and bases such as BF3.Et2O, AlCl3, fluoride ion, and phenoxide ion. Additionally, 3 can be quantitatively desilylated with methanol(without side reactions) to the ''free'' sulfonimidates [HN=S(O)(R1)OR2,7]. The free sulfonimidates, in turn, condense rapidly and quantitatively (at rates approximately two orders of magnitude faster and at temperatures 20 to 40-degrees-C lower, than 3) to poly-(oxothiazenes). The polymers have been characterized by gel permeation chromatography, NMR spectroscopy, thermoanalytical methods, and by elemental microanalysis. Theoretical calculations indicate a cis-trans helical conformation for poly(methyloxothiazene) 4a to be the most stable conformation. A major difference with phosphazene structure geometry is indicated by a near-tetrahedral N-S-N bond angle of 103-degrees.