Ammonolyses of mono(pentamethylcyclopentadienyl) titanium(IV) derivatives [Ti(eta5-C5Me5)X3] (X = NMe2, Me, Cl) have been carried out in solution to give polynuclear nitrido complexes. Reaction of the tris(dimethylamido) derivative [Ti(eta5-C5Me5)(NMe2)3] with excess of ammonia at 80-100 degrees C gives the cubane complex [[Ti(eta5-C5Me5)]4(mu3-N)4] (1). Treatment of the trimethyl derivative [Ti(eta5-C5Me5)Me3] with NH3 at room temperature leads to the trinuclear imido-nitrido complex [[Ti(eta/5-CsMes)(mu-NH)]3(mu3-N)] (2) via the intermediate [[Ti(eta5-C5Me5)Me]2(mu-NH)2] (3). The analogous reaction of [Ti(eta5-C5Me5)Me3] with 2,4,6-trimethylaniline (ArNH2) gives the dinuclear imido complex [[Ti(eta5-C5Me5)Me])2(mu-NAr)2] (4) which reacts with ammonia to afford [[Ti(eta5-C5Me5)(NH2)]2(mu-NAr)2] (5). Complex 2 has been used, by treatments with the tris(dimethylamido) derivatives [Ti(eta5-C5H5-nRn)(NMe2)3], as precursor of the cubane nitrido systems [[Ti4(eta5-C5Me5)3(eta5-C5H5-nRn)](mu3-N)4] [R = Me n = 5 (1), R = H n = 0 (6), R = SiMe3 n = 1 (7), R = Me n = 1 (8)] via dimethylamine elimination. Reaction of [Ti(eta5-C5Me5)Cl3] or [Ti(eta5-C5Me5)(NMe2)Cl2] with excess of ammonia at room temperature gives the dinuclear complex [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) where an intramolecular hydrogen bonding and a nonlineal nitrido ligand bridge the "Ti(eta5-C5Me5)Cl(NH3)" and "Ti(eta5-C5Me5)Cl2" moieties. The molecular structures of [[Ti(eta5-C5Me5)Me]2 (mu-NAr)2] (4) and [[Ti2(eta5-C5Me5)2Cl3(NH3)](mu-N)] (9) have been determined by X-ray crystallographic studies. Density functional theory calculations also have been conducted on complex 9 to confirm the existence of an intramolecular N-H...Cl hydrogen bond and to evaluate different aspects of its molecular disposition.

The ammonolysis of [ T I ( ~~-C ~M ~~) ( N M ~~) ~I at 90 "C affords the nitride complex [{Ti(y5-C,Me,)},(~L,-N)41; the X-ray crystal structure analysis shows a Ti4N4 core clearly similar to the structural motif of cubic titanium nitride.

Several (pyrazolato)potassium complexes have been prepared by deprotonation of the parent pyrazoles with potassium hydride in tetrahydrofuran. A crystal structure of one derivative shows a hexameric formulation, with each potassium atom bonded to the nitrogen atoms of one pyrazolato ligand in an η2-fashion and to the nitrogen atoms of two adjacent pyrazolato ligands with η1-interactions. The utility of these complexes in the synthesis of new pyrazolato complexes is demonstrated.

Treatment of [{Ti(h 5 -C 5 Me 5 )(m-NH)} 3 (m 3 -N)] with alkali metal bis(trimethylsilyl)amido reagents in toluene afforded the complexes [M(m 3 -N)(m 3 -NH) 2 {Ti 3 (h 5 -C 5 Me 5 ) 3 (m 3 -N)}] 2 (M Li (2), Na, (3), K (4)). The molecular structures of 2 and 3 have been determined by X-ray crystallographic studies and show two azaheterometallocubane cores [MTi 3 N 4 ] linked by metal ± nitrogen bonds. Reaction of the lithium derivative 2 with chlorotrimethylsilane or trimethyltin chloride in toluene gave the incomplete cube nitrido complexes [Ti 3 (h 5 -C 5 Me 5 ) 3 (m-NH) 2 (m-NMMe 3 )(m 3 -N)] (M Si (5), Sn (6)). A similar reaction with indium(i) or thallium(i) chlorides yielded cube-type derivatives [M(m 3 -N)(m 3 -NH) 2 {Ti(h 5 -C 5 Me 5 )} 3 (m 3 -N)] (M In (7), Tl (8)).Keywords: alkali metals´cubanesń itrido complexes´titanium[a] Dr.