Molecular nitrides containing group 4 and 5 metals:: Single and double azatitanocubanes

Treatment of [{Ti(eta(5)-C5Me5)(mu-NH)}(3)(mu(3)-N)] (1) with the imido complexes [Ti(NAr)Cl-2(py)(3)] (Ar = 2,4,6-C6H2Me3) and [Ti(NtBu)Cl-2(py)(3)] in toluene affords the single azatitanocubanes [(Cl-2(ArN)Ti}[(mu(3)-NH)(3){Ti-3(eta(5)-C5Me5)(3)-(mu(3)-N)}] . (C7H8) (2 . C7H8) and [{Cl2Ti}-(mu(3)-N)(2)(mu(3)-NH){Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}] (3), respectively. Similar reactions of complex 1 with the niobium and tantalum imido derivatives [(M(NtBu)(NH-tBu)Cl-2(NH(2)tBu)}(2)] (M = Nb, Ta) in toluene give the single azaheterometallocubanes [{Cl-2(tBuN)M)(mu(3)-N)(mu(3)-NH)(2)(Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}] (M=Nb (4), Ta (5)), both complexes react with 2,4,6-trimethylaniline to yield the analogous species [{Cl-2(ArN)M}(mu(3)-N)(mu(3)-NH)(2)-[Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}].(C7H8) (Ar = 2,4,6-C6H2Me3, M = Nb (6.C7H8), Ta (7 . C7H8)). Also the azaheterodicubanes [M{(mu(3)-N)(2)(mu(3)-NH)}(2){Ti-3(eta(5)-C5Me5)(3)-(mu(3)-N)}(2)] . 2C(7)H(8) [M = Ti (8 . 2C(7)H(8)), Zr (9 . 2C(7)H(8))], and [MP{(mu(3)-N)(5)(mu(3)-NH)}-(Ti-3(eta(5)-C5Me5)(3)(mu(3)-N)}(2)] . 2C(7)H8 (Nb (10 . 2C(7)H(8)), Ta (11 . 2C(7)H(8))) were prepared from 1 and the homoleptic dimethylamido complex [M(NMe2)(x)] (x = 4, M = Ti, Zr; x = 5, M = Nb, Ta) in toluene at 150 C. X-ray crystal structure determinations were performed for 6 and 10, which revealed a cube- and double-cube-type core, respectively. For complexes 2 and 4-7 we observed and studied by DNMR a rotation or trigonal-twist of the organometallic ligands [{Ti(eta(5)-C5Me5)(mu-NH)}(3)(mu(3)-N)] (1) and [(mu(3)-N)(mu(3)-NH)(2){Ti-3(eta(5)-C5Me5}(3)(mu(3)-N)](1-). Density functional theory calculations were carried out on model complexes of 2, 3, and 8 to establish and understand their structures.