Transition vanadium nitrides

Titanium and vanadium nitrides may be prepared by a metathesis reaction of their tetrachlorides with the nitride, initiated by heat or friction. The reaction is potentially explosive. Other transition metal halides may cause ampules to explode after thermal initiation when anhydrous and were invariably found to do so when the hydrates were used. 

Further concentration-independent diffusion coefficients were measured for vanadium nitrides [46], hafnium nitrides [88], and chromium carbides, 5TiNi c [89] and 5ZrNi c [90]. Although the metal dilfusivity in transition metal nitrides has not yet been investigated, the activation energy of that process is much higher than for nitrogen diffusion and can be estimated to be of the order of about 8 eV. Tables 3a and 3b summarize some nonmetal diffusivity data of transition metal carbides and nitrides. 

These are usually reactions of anhydrous transition and B metal halides with dry alkali metal salts such as the sulphides, nitrides, phosphides, arsenides etc. to give exchange of anions. They tend to be very exothermic with higher valence halides and are frequently initiated by mild warming or grinding. Metathesis is described as a controlled explosion. Mixtures considered in the specific reference above include lithium nitride with tantalum pentachloride, titanium tetrachloride and vanadium tetrachloride, also barium nitride with manganese II iodide, the last reaction photographically illustrated. 

Electroreduction titanium (IV) iso-propoxide under molecular nitrogen at 1 atm in diglyme led to the generation of titanium nitride species that could be hydrolyzed to yield ammonia [7]. The electrochemical reduction of dinitrogen to ammonia in aqueous electrolytes using vanadium (IV) catecholate mediators and other transition metal systems has been reported, including the titanocene species [8-10]. 

---