Synthesis and characterization of poly(aminoborane) as a new boron nitride precursor

Abstract

During the solution reaction of NaBH 4 /(NH 4 ) 2 SO 4 in tetraglyme to form borazine, polymeric aminoborane (NH 2 BH 2 ) x has been isolated as a white powder. The powder was characterized by thermal gravimetric analysis/differential scanning calorimetry, infrared and mass spectroscopies, and powder X-ray diffraction. Solid-state 15 N and 11 B nuclear magnetic resonance firmly proved that the chain-like poly(aminoborane) evolved a partially condensed B 3 N 3 ring structure by dehydrogenative condensation between chains at 200°C. Pyrolysis of the polymer in a nitrogen stream up to 1400°C led to a 75% yield of hexagonal boron nitride with an interlayer spacing of 3.37 A Ê . Synthesis and Characterization of Poly(aminoborane) / 703 FIGURE 4. Thermal decomposition spectra of poly(aminoborane) for (a) mass 58 mass 73, (b) mass 80 and (c) overall gaseous fragments obtained from mass spectral data. Synthesis and Characterization of Poly(aminoborane) / 707 FIGURE 6. Experimental and simulated 15 N IRCP MAS NMR spectra of the polymer for various inversion time values.FIGURE 7. Evolution versus inversion time of the 15 N IRCP MAS NMR signal intensities of the peaks at À286 and À339 ppm. Curves were ®tted according to equation (1).

Iridium‐Catalyzed Dehydrocoupling of Primary Amine–Borane Adducts: A Route to High Molecular Weight Polyaminoboranes, Boron–Nitrogen Analogues of Polyolefins

“…Because the unsubstituted polyaminoborane ( 2 g ) is isoelectronic with polyethylene, the simplest polyolefin, we characterized this insoluble material in more detail. The IR spectrum (Figure 2 b) of 2 g was similar to that reported by Kim et al.,4c who obtained their material in low yield by a thermal reaction between NaBH 4 and (NH 4 ) 2 SO 4 .…”

“…Powder X‐ray diffraction of the ceramic product showed a semicrystalline material with two major peaks, the first at 2θ=14.9°, d‐spacing 6.0 Å, and the second at 2θ=28.21°, d‐spacing 3.16 Å. The latter peak could be identified as a peak for boron nitride 4c…”

Poly(iminoborane): Eine schwer fassbare Klasse von anorganischen Hauptgruppenpolymeren?

“…Die Pyrolyse von AB im Festkörper verläuft über eine Reihe von aufeinanderfolgenden Dehydrierungsschritten, um schließlich bei ca. 1200 °C hexagonales Bornitrid zu ergeben ,,. Das Zwischenprodukt, das neben Borazin ( III , R=R′=H) im zweiten Dehydrierungsschritt gebildet wird, wurde als unlöslicher, amorpher Feststoff mit der ungefähren Zusammensetzung BNH 2 beschrieben.…”

“…der Formel [BHNH] n in Verbindung gebracht ,,. Neuere Lösungs‐ und Festkörper‐ 11 B‐ und 15 N‐NMR‐Untersuchungen deuten jedoch die Anwesenheit von N 3 B‐ und B 3 N‐ neben N 2 BH‐ und B 2 NH‐Gruppen hin ,,,,. Daher wurde kürzlich vorgeschlagen, dass die Struktur dieses Materials besser als Polyborazylen ( IV ) zu bezeichnen sei, d. h. als ein schlecht definiertes makromolekulares Netzwerk partiell anellierter Borazinringe ,,,.…”

Highly Ordered Boron Nitride Nanotube Arrays with Controllable Texture from Ammonia Borane by Template‐Aided Vapor‐Phase Pyrolysis

“…In order to overcome these problems in our previous study, it was recommended to use a gaseous organometallic precursor of BN for the formation of BNNTs in the PAA template. In this respect, ammonia borane (BH 3 NH 3 ) is considered to be a suitable precursor for the preparation of BNNTs through vapor-phase pyrolysis since BH 3 NH 3 is a stable crystalline solid with less toxicity without C and O and can be easily transformed into the gas phase by moderate temperature heating [14,15]. In addition, no catalyst is needed to synthesize BN using BH 3 NH 3 .…”