Synthesis of New Silyl-Bridged Bis(cyclopentadienyl) Ligands and Complexes

Abstract

The new monobridged compound, [μ-(MePhSi)(C5H5)2] (2), was obtained as a mixture of five positional isomers from the reaction of MePhSiCl2 with 2 equiv of Li(C5H5). Deprotonation of 2 with 2 equiv of nBuLi and subsequent reaction with 1 equiv of Me2SiCl2 in THF resulted in an unsymmetrical dibridged (bis)cyclopentadienyl compound, [μ,μ-(MePhSi)(Me2Si)(C5H4)2] (3). Compound 3 was shown to be a mixture of five isomers by 1D and 2D NMR experiments. Similarly, [μ-(Me2SiCH2CH2SiMe2)(C5H5)2] (4) was deprotonated with 2 equiv of nBuLi and subsequently reacted with 1 equiv of ClMe2SiCH2CH2SiMe2Cl to provide the (bis)cyclopentadienyl compound with two four-atom bridges, [μ,μ-(Me2SiCH2CH2SiMe2)2(C5H4)2] (5). X-ray diffraction studies of sublimed 5 showed the solid state structure to be the symmetrical 1,3−1,3 trans isomer, and NMR studies of 5 indicated a mixture of isomers in solution. The 1H, 13C, 29Si, and VT NMR spectra of compounds 2, 3, and 5 are described. Deprotonation of compounds 2, 3, and 5 and subsequent reaction with 2 equiv of (C5H5)TiCl3 produced the bimetallic complexes [μ-(MePhSi)(C5H4)2][(C5H5)TiCl2]2 (6), 1,2−1,2 trans-[μ,μ-(MePhSi)(Me2Si)(C5H3)2][(C5H5)TiCl2]2 (7), and a mixture of trans and cis isomers of 1,3−1,3 [μ,μ-(Me2SiCH2CH2SiMe2)2(C5H3)2][(C5H5)TiCl2]2 (8).

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

“…The starting 4,4,8,8-tetramethyltetrahydro-4,8-disilas-indacene 1 was isolated using the alternative method reported [14] to prepare various related silanes. As shown in Scheme 1, reaction of the dilithium salt of the mono-silyl-bridged dicyclopentadiene with SiCl 2 Me 2 provided a more direct method to prepare 1 (as a mixture of cis-and trans-isomers) in higher yield (54%) than reported methods [23].…”

“…Many dinuclear compounds containing bridging h 5 -h 1 cyclopentadienyl rings and h 5 -h 5 -fulvalene systems, resulting from ring C H activation in dicyclopentadienyl derivatives, have been reported [1,11]. 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].…”

“…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. The use of this ligand to bridge two different metal atoms as those recently reported [22] demands the earlier isolation of monocyclopentadienyl-type compounds containing only one of the rings h 5 -coordinated to the metal.…”

Dinuclear titanium complexes with methylphenylsilylene bridge between cyclopentadienyl rings. Synthesis, characterization and reactivity towards ethylene

“…Although the preparation of the chelating (C 5 Me 4 ) 2 SiMePh ligand has already been published [12], our attempt to reproduce the procedure led only to a low yield of the desired ligand contaminated in addition by a variety of undefined compounds. Therefore the synthesis of 1 was performed by sequential addition of reagents in one-pot reaction arrangement.…”

Synthesis of double silylene‐bridged binuclear metallocenes and their cooperation effect during ethylene polymerization and ethylene/1‐hexene copolymerization

“…Actually, all the binuclear catalysts Marks investigated were mono-bridged constrained geometry complexes (CGC) or rigid bimetallic phenoxyiminato complexes. On the other hand, doublebridged bisCp ligands restrict the relative orientation of the two metals in the corresponding bimetallic complexes, 10,11 and offer a rigid system in which the metal can bind to the same or opposite faces of the bisCp ligands moiety. Among these types of complexes, the double Me 2 Si bridged bisCp metal complexes, including mononuclear and binuclear types have been studied and summarized in Huang's article.…”