Dicyclopentadienyl titanium and zirconium complexes with the double bridged bis(dimethylsilanodiyl) dicyclopentadienyl [(Me2Si)2(η5-C5H3)2]2− ligand: X-ray molecular structure of [Ti{(SiMe2)2(η5-C5H3)2}Me2]1

Abstract

The reaclion of the doubly bridged bis(l,l',2,2'-dimethylsilantxliyl)-7,,Ldicyclopentadienyl titanium and zirconium complexes [M{(SiMez)a(7~S-C5H,0,}Mea] (M = Ti (3), Zr (4)) wiih water gave the g-oxo derivatives [{M[(SiMe:,) Ansa=metallocene complexes of tbe early transition metals have received considerable attention in recent years [I]. The presence of a bridging group restricts the mobility of the cyclopentadienyl rings, providing a more rigid system that renders the activation of their C-H bonds more difficult.The bis(dimethylsilanodiyl)dicyclope,mldienyl anio,1 [SiMe: (C~H.~):] z-can be coordinated to met:d centers as a chelatilig or as a bridging group. This lig:md has been successfully used to stabilize Group 4 metal coinplexes in both high and low oxidation states. The chemistry of mononuclear compounds with symmetric and asymmetric rings bridged by an SIR+, fi'agment, and tlleir potential applications as catalysts in stereo-and• Correspomlmg aulhor. t Dedicated Io Professor Rafael Us6n on the occasion of his 7t)ih birthday.2 X-ray diffraction studies, enantioseleclive hydrogenation and i~oiymerization of olet'ins, ha.s been extolsively studied. Chiral an.s'a° metallocenes containing :~ C~ syrnnletrical arrangement of ring substituents have also proved to I~ effective precursors tbr generating Zieglea'~Naua catalysts, which induce isotacticity in the polymerization of propylene and other a-olefins [2,3]. Recently, the syntbeses of similar halo-and alkyl-titanium(IV) derivatives [4], as well as new titanium(Ill) and (II) metallocene comiJlexes [5] containing this ligand as a chelating system have been reported, including some aspects of their chemical behavior. Dinuclear compounds are also well represented [6]. although they are less well-known for Group 4 metals [7] and not many dinuclear derivatives of these metals are known in low oxklation states.We were interested in isoklting and studying the reactivity of cyclopentadienyl Group 4 metal complexes by using the bis(dimethylsilanodiyl)dicyclopentadienyl dianion [(SiMe 2)2(~TLC+I°! 3): ]~'-as a ligand to increase the stereorigidity of the complex. Different mono-and oligo-nuclear transition metal derivatives containing this 0022-328X/96/$15.00

Anionic Monosubstituted Cyclopentadienylsamarium Derivatives: Catalysts for a Stereospecific Isoprene Polymerization

“…In addition, in the ansa ligand the rotation of the Cp uterated benzene solution obtained, as described previously, by mixing SmCl 3 (THF) 3 and the Grignard reagent rings [21] [22] is not possible and the effective size of the ligand is therefore smaller. The saturation of the coordination [Me 4 C 2 (C 5 H 4 MgCl) 2 ](THF) 4 .…”

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

“…They will be included in this article to illustrate only those aspects of reactivity immediately related to other functionalized silyl compounds. Detailed studies on these compounds have been reported and reviewed [2,3,9]. This review will focus on the Group 4 -6 transition metal compounds containing ligands with substituted rings of the type C 5 R 4 -SiR 2 -X which contain at least one h 5 -cyclopentadienyl or related indenyl or fluorenyl rings, and one functional X group bonded to silicon.…”

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

“…However di-h 5 -cyclopentadienyl ligands singly bridged by various alkyl [2 -5] and silyl [6][7][8][9][10][11][12][13][14] groups are among the most frequently used systems to bridge dinuclear metal compounds. We have recently reported the use of the 1,1%-2,2%-(dimethylsilanediyl)dicyclopentadienyl ligand to synthesize ansadicyclopentadienyl and bridged homodinuclear monoand di-cyclopentadienyl complexes of the Group 4 and 6 metals [15][16][17][18][19][20]. This and related doubly silyl-bridged ligands have also been used [14,21] to isolate mononuclear and dinuclear Group 4 metal compounds.…”