This is a sample of a few grams of very pure niobium pentachloride. This is a crystalline solid, which is extremely air-sensitive. The solid fumes in contact with humid air and is very easily hydrolysed to NbOCl₃ and HCl. Further water hydrolyses this to hydrous Nb₂O₅ and more HCl.

Niobium pentachloride is a purely covalent compound, with a low melting point, and it also easily volatilizes. The pictures below show the molten compound and the compound in the gas phase, at ordinary pressure:

The compound melts at 205 ºC and it boils at 254 ºC, but when it is heated, even before the solid melts, one can easily see the yellow vapor already.