Molecular Nitrides Containing Group 4 and 5 Metals: Single and Double Azatitanocubanes

Treatment of [{Ti( η 5 ‐C 5 Me 5 )( μ ‐NH)} 3 ( μ 3 ‐N)] ( 1 ) with the imido complexes [Ti(NAr)Cl 2 (py) 3 ] (Ar=2,4,6‐C 6 H 2 Me 3 ) and [Ti(N t Bu)Cl 2 (py) 3 ] in toluene affords the single azatitanocubanes [{Cl 2 (ArN)Ti}( μ 3 ‐NH) 3 {Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)}]⋅(C 7 H 8 ) ( 2 ⋅C 7 H 8 ) and [{Cl 2 Ti}( μ 3 ‐N) 2 ( μ 3 ‐NH){Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)}] ( 3 ), respectively. Similar reactions of complex 1 with the niobium and tantalum imido derivatives [{M(N t Bu)(NH t Bu)Cl 2 (NH 2 t Bu)} 2 ] (M=Nb, Ta) in toluene give the single azaheterometallocubanes [{Cl 2 ( t BuN)M}( μ 3 ‐N)( μ 3 ‐NH) 2 {Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)}] (M=Nb ( 4 ), Ta ( 5 )), both complexes react with 2,4,6‐trimethylaniline to yield the analogous species [{Cl 2 (ArN)M}( μ 3 ‐N)( μ 3 ‐NH) 2 {Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)}]⋅(C 7 H 8 ) (Ar=2,4,6‐C 6 H 2 Me 3 , M=Nb ( 6 ⋅C 7 H 8 ), Ta ( 7 ⋅C 7 H 8 )). Also the azaheterodicubanes [M{( μ 3 ‐N) 2 ( μ 3 ‐NH)} 2 {Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)} 2 ]⋅2C 7 H 8 [M=Ti ( 8 ⋅2C 7 H 8 ), Zr ( 9 ⋅2C 7 H 8 )], and [M{( μ 3 ‐N) 5 ( μ 3 ‐NH)}{Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)} 2 ]⋅2 C 7 H 8 (Nb ( 10 ⋅2C 7 H 8 ), Ta ( 11 ⋅2C 7 H 8 )) were prepared from 1 and the homoleptic dimethylamido complex [M(NMe 2 ) x ] ( x =4, M=Ti, Zr; x =5, M=Nb, Ta) in toluene at 150 °C. Xray 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( η 5 ‐C 5 Me 5 )( μ ‐NH)} 3 ( μ 3 ‐N)] ( 1 ) and [( μ 3 ‐N)( μ 3 ‐NH) 2 {Ti 3 ( η 5 ‐C 5 Me 5 ) 3 ( μ 3 ‐N)}] 1− . Density functional theory calculations were carried out on model complexes of 2, 3 , and 8 to establish and understand their structures.