TY - JOUR
T1 - Synthesis and Structure of Borazinyl-Substituted Small-Molecule and High Polymeric Phosphazenes
T2 - Ceramic Precursors
AU - Allcock, Harry R.
AU - Welker, Mark F.
AU - Parvez, Masood
PY - 1992/2/1
Y1 - 1992/2/1
N2 - Mixed-substituent small-molecule cyclic and high molecular weight polymeric (borazinylamino)phosphazenes have been prepared by reactions between aminophosphazenes and chloroborazines as well as between chlorophosphazenes and aminoborazines. A single-crystal X-ray diffraction study of a small-molecule model compound, gem-bis(borazinylamino)cyclotriphosphazene, N3P3(NMe2)4 (NHB3N3Me5)2 (10), is reported: triclinic, space group P1, a = 9.424 (2) Å, b = 13.841 (1) Å, c = 14.570 (4) Å, α = 79.40 (1)°, β = 83.44 (2)°, γ = 73.99 (1)°, V = 1791.5 Å3, Z = 2, Dc = 1.187 g cm-3, Mo Kα radiation, λ = 0.71073 Å, µ = 0.196 mm-1, R = 0.066. The exocyclic P-N and B-N bond lengths of the borazinylamino substituents indicate significant derealization of the nitrogen atom lone pair, with preference into the borazinyl ring rather than the phosphazene ring. Pyrolysis studies of the mixed-substituent (borazinylamino)phosphazene polymers indicate that these polymers are potential precursors to new ceramic materials, with up to 57% ceramic yield when heated to 1000 °C under nitrogen. Continued pyrolysis at 1300 °C for 10 h leads to the production of crystalline hexagonal boron nitride.
AB - Mixed-substituent small-molecule cyclic and high molecular weight polymeric (borazinylamino)phosphazenes have been prepared by reactions between aminophosphazenes and chloroborazines as well as between chlorophosphazenes and aminoborazines. A single-crystal X-ray diffraction study of a small-molecule model compound, gem-bis(borazinylamino)cyclotriphosphazene, N3P3(NMe2)4 (NHB3N3Me5)2 (10), is reported: triclinic, space group P1, a = 9.424 (2) Å, b = 13.841 (1) Å, c = 14.570 (4) Å, α = 79.40 (1)°, β = 83.44 (2)°, γ = 73.99 (1)°, V = 1791.5 Å3, Z = 2, Dc = 1.187 g cm-3, Mo Kα radiation, λ = 0.71073 Å, µ = 0.196 mm-1, R = 0.066. The exocyclic P-N and B-N bond lengths of the borazinylamino substituents indicate significant derealization of the nitrogen atom lone pair, with preference into the borazinyl ring rather than the phosphazene ring. Pyrolysis studies of the mixed-substituent (borazinylamino)phosphazene polymers indicate that these polymers are potential precursors to new ceramic materials, with up to 57% ceramic yield when heated to 1000 °C under nitrogen. Continued pyrolysis at 1300 °C for 10 h leads to the production of crystalline hexagonal boron nitride.
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U2 - 10.1021/cm00020a015
DO - 10.1021/cm00020a015
M3 - Article
AN - SCOPUS:0012611620
VL - 4
SP - 296
EP - 307
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 2
ER -