Li+ [N≡C−S−] | |
| Names | |
|---|---|
Other names
| |
| Identifiers | |
| |
3D model (JSmol) |
|
| ChemSpider | |
| ECHA InfoCard | 100.008.306 |
| EC Number |
|
| |
| |
| Properties | |
| LiSCN | |
| Molar mass | 65.02 g/mol |
| Appearance | White hygroscopic solid |
| Density | 1.44 g/cm3[1] |
| Melting point | 274 °C (525 °F; 547 K)[2] |
| Boiling point | 550 °C (1,022 °F; 823 K) (decomposition) |
| 125 g/100 ml | |
| Solubility | Soluble inalcohol[1] |
| Structure[2][3] | |
| Orthorhombic (anhydrous, α-monohydrate, dihydrate) Monoclinic (β-monohydrate) | |
| C2/m (α-monohydrate) Pnam (β-monohydrate) Pnma (anhydrous, dihydrate) | |
a = 1215.1pm,b = 373.6 pm,c = 529.9 pm (anhydrous) | |
| 4 (α, β-monohydrate) 6 (anhydrous, dihydrate) | |
| Tetrahederal (α and β-monohydrate) | |
| Thermochemistry | |
Std molar entropy(S⦵298) | 9 e.u.[1] |
Std enthalpy of formation(ΔfH⦵298) | 5.0 kcal/mol[1] |
| Hazards | |
| GHS labelling: | |
 | |
| Warning | |
| H302+H312+H332,H412 | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Othercations | Sodium thiocyanate,Potassium thiocyanate |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Lithium thiocyanate is a chemical compound with the formula LiSCN. It is an extremelyhygroscopic white solid that forms themonohydrate and the dihydrate. It is the least stable of the alkali metalthiocyanates due to the large electrostatic deforming field of the lithium cation.[1]
Lithium thiocyanate is hygroscopic and forms the anhydrous, monohydrate, and dihydrate, which melts at 274, 60, and 38 °C, respectively.[2] The monohydratesupercools after melting, as it recrystallizes at 36 °C. It is soluble in many organic solvents, such asethanol,methanol,1-propanol, andacetone. However, it is insoluble inbenzene.[1]
Due to its hygroscopicity, the anhydrous form is hard to prepare. The anhydrous form is usually prepared by the reaction oflithium hydroxide andammonium thiocyanate, then the water was removed by vacuum, then the resulting solid was dissolved indiethyl ether, followed by adding topetroleum ether to form the ether salt, then it was heated in vacuum at 110 °C to result in the anhydrous salt. The overall reaction is the following:[1]
The ether can be replaced byTHF.[2]
The monohydrate has 2 forms, the α form, and the β form; the α form reversibly converts to the β form at 49 °C. The α form has thespace groupC2/m while the β form has the space groupPnam. More info on its crystallography are listed in the table below.
| Compound | LiSCN[3] | α-LiSCN·H2O[2] | β-LiSCN·H2O[2] | LiSCN·2H2O[3] |
|---|---|---|---|---|
| Molar mass (g/mol) | 65.02 | 83.04 | 83.04 | 101.05 |
| Crystal Structure | Orthorhombic | Orthorhombic | Monoclinic | Orthorhombic |
| Space Group | Pnma | C2/m | Pnam | Pnma |
| Lattice constant a (Å) | 12.151 | 15.027 | 13.226 | 5.721 |
| Lattice constant b (Å) | 3.736 | 7.597 | 7.062 | 8.093 |
| Lattice constant c (Å) | 5.299 | 6.707 | 8.166 | 9.66.9 |
| β | 96.147° | |||
| Coordination number | 6 | 4 | 4 | 6 |
| Calculated density (g/cm3) | 1.80 | 1.45 | 1.45 | 1.50 |
