-hydride%2c_2D.png) | |||
| |||
| Names | |||
|---|---|---|---|
| Systematic IUPAC name Titanium(IV) hydride | |||
| Other names Titanium tetrahydride Titane TiH4 | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChemSpider | |||
| ECHA InfoCard | 100.035.414 | ||
| EC Number |
| ||
| UN number | 1871 | ||
| |||
| |||
| Properties | |||
| TiH4 | |||
| Molar mass | 51.899 g/mol | ||
| Appearance | Colourless gas | ||
| Reacts | |||
| Related compounds | |||
Otheranions | Titanium(IV) fluoride Titanium(IV) chloride Titanium(IV) bromide Titanium(IV) iodide | ||
Othercations | Methane Silane Germane Stannane Plumbane | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Titanium(IV) hydride (systematically namedtitanium tetrahydride) is aninorganic compound with theempiricalchemical formulaTiH
4. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular titanium(IV) hydride has been isolated in solid gas matrices. The molecular form is a colourless gas, and very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated viacomputational chemistry.
Titanium(IV) hydride was first produced in 1963 by thephotodissociation of mixtures ofTiCl4 andH2, followed by immediatemass spectrometry.[1] Rapid analysis was required as titanium(IV) hydride is extremely unstable. Computational analysis ofTiH4 has given a theoreticalbond dissociation energy (relative to M+4H) of 132 kcal/mole.[2] As the dissociation energy ofH2 is 104 kcal/mole the instability ofTiH4 can be expected to bethermodynamic; with it dissociating to metallictitanium andhydrogen:
TiH4, along with other unstable molecular titanium hydrides, (TiH,TiH2,TiH3 and polymeric species) has been isolated at low temperature followinglaser ablation of titanium.[3]
It is suspected that within solid titanium(IV) hydride, the molecules form aggregations (polymers), being connected bycovalent bonds.[4] Calculations suggest thatTiH4 is prone todimerisation.[3] This largely attributed to the electron deficiency of the monomer and the small size of the hydride ligands; which allows dimerisation to take place with a very lowenergy barrier as there is a negligible increase in inter-ligand repulsion.
The dimer is a calculated to be afluxional molecule rapidly inter-converting between a number of forms, all of which displaybridging hydrogens.[4] This is an example ofthree-center two-electron bonding.
Monomeric titanium(IV) hydride is the simplest transition metal molecule that displays sd3orbital hybridisation.[5]
-hydride-3D-balls.png)
