574742-00-0Relevant articles and documents
Synthesis and structural characterisation of new organo-diimido tantalum and niobium complexes
Antinolo, Antonio,Dorado, Ivan,Fajardo, Mariano,Garces, Andres,Kubicki, Marek M.,Lopez-Mardomingo, Carmen,Otero, Antonio
, p. 910 - 917 (2007/10/03)
The organo-diimido tantalum complexes [{Ta(L2)Cl 3}2(μ-1,n-NC6H4N)], L = MeCN (1) and 4-tBupy (2), have been prepared by two alternative experimental methods: (1) the initial formation of the corresponding TaCl5· adduct, L = 4-tBupy or CH3CN, followed by addition of the appropriate phenylenediamine, or (2) the initial formation of the corresponding organo-diimido species and subsequent addition of the ligand L. These complexes, as well as some related niobium complexes, were alkylated using the appropriate Grignard reagent to afford the alkyl-containing complexes [{M(L)R3}2(μ-1,n-NC6H4N)] (4, 5, 6, 7, 8, 9) (M = Nb, Ta; n = 3, 4; L = MeCN, R = CH2SiMe3, CH2CMe3, CH2CMe2Ph). These complexes can be prepared by treating the corresponding chloro-complexes with dialkyl-magnesium reagents MgR2(THF)2. Niobium complexes containing THF ligands, i.e. [{Nb(THF)R3}2(μ-1, 3-NC6-H4N)] (10, 11) (R = CH2SiMe3, CH2CMe3), were isolated by using THF as the solvent and also from the acetonitrilecontaining complexes 8b and 9b by simply adding THF. The complex [{Nb(CH2CMe2Ph)3} 2(μ-1,4-NC6H4N)] (12a) was prepared by addition of the corresponding Grignard reagent to a suspension of [{Nb(MeCN)2Cl3}2(μ-1,4-NC6-H4N)] in THF. The reaction of complexes [{M(MeCN)2Cl3} 2(μ-1,n-NC6H4N)] (M = Ta, Nb; n= 3, 4) with Li[C5H4-SiMe3] was carried out and afforded the tetrakis-cyclopentadienyl-diimido complexes [{M(??5-C 5H4SiMe3)2Cl}2-(μ-1,n- NC6H4N)] [M = Ta, n= 4 (13a); M = Ta, n = 3 (13b); M = Nb, n = 4 (14a); M = Nb, n = 3 (14b)]. The structure of 13a has been solved by X-ray diffraction. Finally, we have performed the reactions between the diimido-containing compounds [{M(MeCN)2Cl3} 2(μ-1,n-NC6H4N)] (M = Ta, Nb; n = 3,4) and the lithium benzamidinate Li[PhC-(NSiMe3)2] to afford the benzamidinate-containing complexes [{M[PhC(NSiMe3)] 2Cl}2(μ-1,n-NC6H4N)] [M = Ta, n = 4 (15a); M = Ta, n= 3 (15b); M = Nb, n = 4(16a)]. The structures of the different families of compounds were determined by spectroscopic methods. The Royal Society of Chemistry 2003.
