A silicide hydride is a mixed anion compound that contains silicide (Si4− or clusters) and hydride (H−) anions. The hydrogen is not bound to silicon in these compounds. These can be classed as interstitial hydrides, Hydrogenated zintl phases, or Zintl phase hydrides.[1] In the related silanides, SiH3− anions or groups occur. Where hydrogen is bonded to the silicon, this is a case of anionic hydride, and where it is bonded to a more complex anion, it would be termed polyanionic hydride.[1]
Silicide hydrides may be prepared by heating a Zintl phase or metal silicide under hydrogen pressure, of perhaps 20 atmospheres.[2]
In CaSiD1+x the deuterium atom (D) fits in a tetrahedral hole between three calcium and one silicon atoms. The Si-D distance is 1.82 Å, quite a bit further than then a Si-H covalent bond.[3]
formula | system | space group | unit cell Å | volume | density | comment | reference |
---|---|---|---|---|---|---|---|
Li4Si2H | orthorhombic | Cmmm | zigzag Si chains Si-Si 2.39 | [4] | |||
CaSiH | [3] | ||||||
CaSiH1+x x<1.2 | orthorhombic | Pnma | a = 14.4884, b = 3.8247, c = 11.2509, Z = 3 | zigzag Si chains Si-Si 2.47 | [4] | ||
CaAlSiH | trigonal | Z=1 | Al-H bond semimetal | [4] | |||
Ca2SiH2.41 | amorphous | a=5.969 b=3.6146 c=6.815 | reversible hydrogen storage | [4] | |||
Ca5Si3H0.53 | tetrahedral | I4/mcm | a=7.6394 c=14.7935 Z=4 | 863.33 | [1][5] | ||
SrSiH1.6 | orthorhombic | Pnma | [6] | ||||
SrAlSiH | P3m1 | Al-H bond semimetal | [4] | ||||
SrGaSiH | trigonal | P3m1 | Z=1 | grey; Ga-H 1.71 semimetal | [4][7] | ||
Sr21Si2O5H21+x | cubic | Fd3m | a = 19.1190 | [8] | |||
BaSiH3.4 | orthorhombic | Pnma | [6] | ||||
Ba3Si4Hx (x = 1–2) | tetrahedral | I4/mcm | a ≈ 8.44, c ≈ 11.95, Z = 8 | Si46– in a butterfly-shape | [2] | ||
Ba21Si2O5H21+x | cubic | Fd3m | a = 20.336 | [8] | |||
BaAlSiH | Al-H bond semimetal | [4] | |||||
BaGaSiH | trigonal | P3m1 | a=4.2934 c=5.186 Z=1 | 82.79 | grey; air stable; Ga-H 1.71 semimetal | [4][7] | |
BaGaSiD | trigonal | P3m1 | a=4.2776 c=5.1948 Z=1 | 82.32 | grey | [7] | |
LaFeSiH | tetragonal | P4/nmm | a=4.0270 c=8.0374 | [9] | |||
LaFeSiH | orthorhombic | Cmme | a=5.6831 b=5.7037 c=7.9728 | at 15K; superconductor Tc=9.7K | [10] | ||
La3Pd5SiD~1.6 | orthorhombic | Imma | a=13.193 b=7.638 c=7.916 | 801.8 | <9.5 bar | [11] | |
La3Pd5SiD~2.71 | orthorhombic | Imma | a=13.102 b=7.673 c=8.168 | 821.3 | [11] | ||
La3Pd5SiD~5 | orthorhombic | Pmnb | a=13.16 b=7.91 c=8.20 | 854 | >75 bar | [11] | |
BaLaSi2D0.80 | orthorhombic | Cmcm | a = 4.6443, b = 15.267, c = 6.7630 | [12] | |||
NdScSiH1.5 | tetrahedral | I4/mmm | a=4.221 c=16.928 Z=4 | [13] | |||
EuSiH1.8 | orthorhombic | Pnma | [6] | ||||
GdMnSiH | tetragonal | P4/nmm | [14] | ||||
GdFeSiH | tetragonal | P4/nmm | a=3.901 c=7.503 | 114.2 | [14] | ||
GdCoSiH | tetragonal | P4/nmm | a=3.879 c=7.439 | 111.9 | [14] |