Dinitrogen titanium complexes

Teuben and de Liefde Meijer (64) prepared the first well-characterized titanium dinitrogen complex. They found that toluene solutions of phenyl-dicyclopentadienyltitanium(III) (26) when cooled under N2 gave an intense blue coloration ascribed to the reversible formation of a dinitrogen adduct. 

Bis(cyclopentadienyl)titanium(II) dicarbonyl complexes, preparation and reactivity, 4, 250 Bis(cyclopentadienyl)titanium(II) dinitrogen complexes, preparation and reactivity, 4, 250 Bis(cyclopentadienyl)titanium halides ligand metathesis reactions, 4, 537 olefin polymerization, 4, 538 organic reactions, 4, 540 properties, 4, 530 reductions, 4, 532 synthesis, 4, 510... 

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 compound [ (T -CsHs TiCH CiCHg) ] has been characterized (337). Its homologs are well known. Surface anchoring of titanium complexes to Si02 in order to produce heterogeneous, supported dinitrogen complexes has not been successful (202). 

The bis(i7-pentamethylcyclopentadienyl)zirconium dinitrogen complex [tj-C5(CH3)5kZrj(N2)3 (22), in solution reversibly releases its dinitrogen in vacuo over several hours (Section III,E). The solutions remaining are said to consist mainly of [T7-C5(CH3)5][T7-C5(CH3)4CH2]ZrH (23) (33). Permethylzirconocene [tj-C5(CH3 )5l,Zr (24) may exist in these solutions in equilibrium with this hydride tautomer (as in the case of titanium). However, thus far permethylzirconocene has not been isolated as a discrete compound or otherwise characterized. It is very likely that permethylzirconocene is less stable and more prone to form complex metallocene hydrides than permethyltitanocene (16). 

A bis(i7-cyclopentadienyl)titanium(III) alkyl dinitrogen complex was prepared by reaction of [(i7-C5H5)2TiCl]2 with isopropylmagnesium chlo-... 

There are no dinitrogen complexes of any of these metals that contain a phosphine ligand. The considerable amount of nitrogen-fixing chemistry reported for titanium, and to a lesser extent zirconium, involves alkoxide, cyclopentadienyl, and halide complexes.The catalytic nitriding reactions of titanium will be reviewed in Section 3. 

Titanium(IV) chloride forms a number of different adducts with trans-[ReCl(N2)(PMe2Ph)4] (see Table 1) that are believed to involve dinitrogen bridging between rhenium and titanium. Hydrolysis or treatment of these adducts with ethanol results in the virtual quantitative recovery of the original rhenium-dinitrogen complex. 

Hanna TE, Lobkovsky E, Chirik PJ. Dinitrogen activation by titanium sandwich complexes. J m Chem Soc. 2004 126 14688-14689. 

Hanna TE, Keresztes I, Lobkovsky E, Bemskoetter WH, Chirik PJ. Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti = NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates. Organometallics. 2004 23 3448-3458. 

---