Poly(iminoborane)s: An Elusive Class of Main‐Group Polymers?

Abstract

The significance of inorganic main-group polymers is demonstrated most clearly by the commercial relevance of polysiloxanes (silicones). Organoboron-based materials such as π-conjugated organoborane polymers and BN-doped polycyclic aromatic hydrocarbons are currently attracting considerable attention. Surprisingly, poly(iminoborane)s (PIBs; [BRNR'] ), that is, the parent unsaturated BN polymers, which are formally isoelectronic to polyacetylene, have not been convincingly characterized thus far. Herein, we present the synthesis and comprehensive characterization of a linear oligo(iminoborane), which comprises a chain of 12-14 BN units on average. With our synthetic approach, unwanted side reactions that result in borazine formation are effectively suppressed. Supporting DFT and TD-DFT calculations provide deeper insight into the microstructure and the electronic structure of the oligomer.

A BN Aromatic Ring Strategy for Tunable Hydroxy Content in Polystyrene

“…[15,[27][28][29][30][31] We described the synthesis and gram-scale free radical polymerization of BN 2-vinylnaphthalene (BN2VN), as well as the preparation of copolymers with 2-vinylnaphthalene (2VN). [15,[27][28][29][30][31] We described the synthesis and gram-scale free radical polymerization of BN 2-vinylnaphthalene (BN2VN), as well as the preparation of copolymers with 2-vinylnaphthalene (2VN).…”

Doping the Backbone of π‐Conjugated Polymers with Tricoordinate Boron: Synthetic Strategies and Emerging Applications

“…[54] Moreover,t he parent unsaturated B=Np olymers, that is, poly(iminoborane)s (PIBs), which are formally derived from polyacetylene (PA), have never been convincingly characterized until very recently through the work by Helten and co-workers. [55] The preferred formation of borazines, i.e.,c yclic iminoborane trimers, whicha re (as being BN/CC isosteres of benzene) relatively stable compounds, seemedt ob et he major obstacle to overcome in the intended synthesis of poly(iminoborane)s. Heltena nd co-workersdevised aconcept to preventunwanted side reactions that result in borazine formation. [55] They linked the adjacent nitrogen centers of the main chain pairwise via an ethylene bridge.…”

“…[55] The preferred formation of borazines, i.e.,c yclic iminoborane trimers, whicha re (as being BN/CC isosteres of benzene) relatively stable compounds, seemedt ob et he major obstacle to overcome in the intended synthesis of poly(iminoborane)s. Heltena nd co-workersdevised aconcept to preventunwanted side reactions that result in borazine formation. [55] They linked the adjacent nitrogen centers of the main chain pairwise via an ethylene bridge. Reactions of 1,3-bis(trimethylsilyl)-1,3,2-diazaborolidines with variousd ichloroboranes brought aboutS i/ Be xchange polycondensation to yield oligomeric poly(iminoborane)s 69 a-e,a nd after end-capping, 70 a-e,w ith molecular weights up to M n = 2.5 kDa (Scheme 23).…”

“…The BN-doped cyclolinear conjugated polymers by Helten et al [50,53,55] are potentially of interest for wide-band gap applications. [61] The benzodiazaboroline buildingb lock, present in copolymerss uch as 23 a-c (Scheme 9), was classified as a mediume lectron-donating unit by Yamamoto and coworkers.…”

Reactivity of a coordinated inorganic acetylene unit, HBNH, and the azidoborane cation [HB(N3)]+

“…1,2 In seminal studies, Paetzold and coworkers used steric protection to obtain iminoboranes ( e.g. t BuBN t Bu) as stable entities, and demonstrated initial coordination chemistry.…”