Titanium dinitrogen derivatives

Titanium cyclopentadienyl derivatives form an extensive series of dinitrogen complexes. However, when the titanium-containing precursors are bound to polymers there is no reactivity with dinitrogen comparable to that observed for the analogous derivatives in solution, and fixation is, at best, marginal (202, 220). 

The bis(rj-cyclopentadienyl)titanium(III) aryl complexes form interesting dinitrogen derivatives (Section III,B) the 1-methyl, 17-allyl complex (Tj-C5H5)2Ti(i73-C4H7) is the precursor to a particularly effective homogeneous olefin hydrogenation catalyst (Section VI). Attempts to prepare bis(i7-cyclopentadienyl)titanium(III) monoalkyl complexes were unsuccessful (40). 

Modified Forms in Common Use. There are numerous situations in which the foregoing system does not meet all requirements. In the formation uf binary compounds, several elements exhibit more Ilian two states of oxidation. One method, recommended by the IUPAC, of handling these situations is the use of prefixes derived from Greek to indicate stoichiometric composition, e.g., titanium dichloride, TiCL and dinitrogen oxide (nitrous oxide) N 0. Other accepted methods ofindicating proportions of constituents are the Stock system (oxidation number) and the Ewens-Bassett (charge number) system. 

Apart from the compounds already mentioned, vanadium, manganese, and cobalt chlorides, tetra-alkoxy derivatives of titanium, acetylacetonates of V, Cr, Mo, Mn, and Ni, Cp derivatives of Zr and Nb, and triphenyl phosphine complexes of Ti and Fe were found to be active. Later lanthanide complexes were included in the list of dinitrogen-reducing systems, the most effective being compounds of samarium and yttrium. 

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