8_chemdraw.png) | |
8_avogadro1.png) | |
| Names | |
|---|---|
| IUPAC name Potassium octacyanidomolybdate(IV) | |
| Other names Potassium octacyanomolybdate(IV) | |
| Identifiers | |
| |
3D model (JSmol) |
|
| |
| |
| |
| Properties | |
| K4[Mo(CN)8] | |
| Molar mass | 460,47 g/mol (anhydrous) 496.5 g/mol (dihydrate) |
| Appearance | yellow powder |
| Melting point | >300 °C |
| Hazards | |
| GHS labelling: | |
 | |
| Warning | |
| H302,H315,H319,H335 | |
| P261,P305+P351+P338 | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Potassium octacyanomolybdate(IV) is the inorganic salt with the formula K4[Mo(CN)8]. A yellow light-sensitive solid, it is thepotassium salt of thecyanometalate with thecoordination number eight. The complexanion consists of aMo(IV) center bound to eightcyanideligands resulting in an overallcharge of −4, which is balanced with four potassiumcations. The salt is often prepared as itsdihydrate K4[Mo(CN)8].(H2O)2.
The dihydrate K4[Mo(CN)8] · 2 H2O can be prepared by the reduction ofmolybdate (MoO42-) withpotassium borohydride (KBH4) in a solution withpotassium cyanide andacetic acid.[1][2] Yields of 70% are typical and the method is suited for scale-up.
An alternative route starts fromMoCl4(Et2O)2 avoiding the need for reductants. The yield of this route is typically around 70%.[3] This synthesis is convenient for lower batch sizes than the earlier method but the MoCl4(Et2O)2 is typically less available than the molybdate.
Octacyanomolybdate(IV) can be oxidized to theparamagnetic octacyanomolybdate(V).
The cyanide ligands in [Mo(CN)8]4- remain basic. Strong acids lead to thehydrogen isocyanide complex [Mo(CNH)8]4+, in common with manycyanometalate complexes.[4] These ligands can be substituted by others, for example H2O. The cyanide ligands also bind to other metals, leading to cages.[2]