Transition metal complexes with functionalized silyl-substituted cyclopentadienyl and related ligands: synthesis and reactivity

Aryl-imido niobium complexes with chloro-silyl and aryl-η-amidosilyl cyclopentadienyl ligands: X-ray structure of the constrained-geometry compound [Nb(η5-C5H4SiMe2-η1-NAr)(NAr)Cl] (Ar=2,6-Me2C6H3)

“…The remaining solution was cooled to À38°C to give complex 3a as a yellow crystalline solid (0.70 g, 60% yield). Data for 3a: 1 …”

“…The presence of different functionalities on cyclopentadienyl ligands allows the reactivity of their metal complexes to be modified, inducing changes in both steric and electronic effects on the metal centres [1]. When this functionality on the ring is the [SiMe 2 Cl] group, the reactivity of the Si-Cl bond facilitates access to a versatile range of products, including catalysts anchored on solid supports [2][3][4][5] and silylamido bridge formation between the cyclopentadienyl ligand and the metal centre (constrained-geometry complexes) [6][7][8][9][10][11].…”

Synthesis and reactivity of imido niobium complexes containing the functionalized (dichloromethylsilyl)cyclopentadienyl ligand

“…The use of (trimethylsilyl)silylcyclopentadienyl derivatives C 5 H 4 (SiMe 3 )X has been demonstrated to be a successful method to synthesize niobium complexes with functionalized cyclopentadienyl ligands [1] (3) by the addition of SiCl 3 Me, through the chloro-amido exchange reaction. The 1 H NMR spectrum of compound 2 showed the ABCD pattern for the C 5 H 4 group expected for the presence of a chiral silicon atom, whereas for compound 3 the AA 0 BB 0 pattern observed for 1 was recovered.…”

“…The presence of different functionalities attached to the cyclopentadienyl ligands determines both the steric and electronic properties of the metal centres and modifies the reactivity of their complexes [1]. A particularly useful functionality is that containing a chlorosilyl group because the reactivity of the Si-Cl bond facilitates the formation of the silyl-g-amido bridge between the cyclopentadienyl ligand and the metal centre [2][3][4][5][6][7][8].…”

Synthesis and characterization of η5-cyclopentadienyl–silylallyl niobium and tantalum complexes

“…Desilylation of silylcyclopentadienes by reaction with electrophilic metal halides is a convenient method [10] to prepare silylcyclopentadienyl niobium [11], tantalum [12] and group 6 metal [13] complexes. The selectivity of this reaction, when two different silyl groups are bound to the ring, is not only dependent on the nature of the silyl substituents but also on the metal halide.…”