A new potassium tetraamidoboranealuminate, K[Al(NH
2BH
3)
4], has been synthesized by a mechanochemical reaction between KAlH
4 and NH
3BH
3. The compound, K[Al(NH
2BH
3)
4], crystallizes in a triclinic unit cell with space group symmetry
P?1. The crystal structure consists of [K(NH
2BH
3)
6]
5? octahedra which facilitate the bridging between K
+ in 1D chains, while also bridging K
+ to Al
3+ to connect the 1D chains in a 3D network. Thermal analysis reveals that K[Al(NH
2BH
3)
4] decomposes in two exothermic steps at
T ~ 94 and 138 °C and releases primarily hydrogen. The total gas release amounts to ~6.0 wt% H
2. The decomposition products are investigated
ex situ by powder X-ray diffraction, infrared spectroscopy, and
11B and
27Al NMR and identified as KBH
4 and amorphous phases, possibly BN
3, N
2BH, and/or NBH
2 whereas aluminum is found in four-, five-, and six-fold coordination. Unfortunately, the decomposed sample shows no hydrogen absorption at
T = 260 °C and
p(H
2) = 110 bar.
相似文献