Structural analysis of a melaminium polyphosphate from X-ray powder diffraction and solid-state NMR data

被引:10
作者
Brodski, V
Peschar, R
Schenk, H
Brinkmann, A
Bloemberg, TG
van Eck, ERH
Kentgens, APM
机构
[1] Univ Amsterdam, Hoff Inst Mol Sci, Crystallog Lab, NL-1018 WV Amsterdam, Netherlands
[2] Radboud Univ Nijmegen, Inst Mol & Mat, NL-6525 ED Nijmegen, Netherlands
关键词
D O I
10.1021/jp0512715
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The crystal structure of the environmentally friendly flame retardant melaminium polyphosphate (MPoly) (2,4,6-triamino-1,3,5-triazinium-PO3)(n) was determined by a direct-space global optimization technique from X-ray powder diffraction data. Solid-state NMR was used to corroborate the proposed hydrogen-bonding model and to determine the average degree of polymerization (n > 100). An analysis of the crystal structure of MPoly reveals aspects of molecular geometry and packing that are characteristic for melamine-containing compounds and polyphosphate salts. A comparison of MPoly with the crystal structures of its precursors melaminium orthophosphate (MP) and melaminium dihydrogenpyrophosphate (MPy) provides insight in the mechanism of the endothermic dehydration processes that takes place in the reaction path MP -> MPy -> MPoly. Solid-state NMR characterization of various samples of the same batch showed inhomogeneities in the MPoly composition. Various quantities of orthophosphates were found, which cannot be assigned to be MP.
引用
收藏
页码:13529 / 13537
页数:9
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