A doubly bridged isodicyclopentadienyl zirconium complex: bis{N-(3,5-dimethylphenyl)-N-[(η5-isodicyclopentadien-2-yl)dimethylsilyl]amido-κN}zirconium(II) diethyl ether solvate

Transmetallation of the dilithium salt of (3,5-dimethyphenylamino)(isodicyclopentadienyl)dimethylsilane by treatment with zirconium tetrachloride in a 2:1 ratio leads to the substitution of all four chloride ligands. With the applied stoichiometry, the title complex, [Zr(C(20)H(25)NSi)(2)].C(4)H(10)O, was obtained and crystallized from diethyl ether. X-ray diffraction characterization showed that both isodicyclopentadienyl ligands (alternatively called 4,5,6,7-tetrahydro-4,7-methano-1H-indene) are complexed to the metal on their exo face in a completely stereoselective manner and that they are eta(5)-bonded to the Zr atom.

ansa-[(tert-Butylamino)(isodicyclopentadienyl)dimethylsilane]Zr(NMe2)2prepared by an amine-elimination reaction

An amine-elimination reaction was used to obtain the title compound, i.e. (N-tert-butyl-N-[[(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro-4,7-methano-1H-inden-2-yl]dimethylsilyl]amido-kappaN)bis(N-methylmethanaminato-kappaN)zirconium(IV) or [isodiCpSiMe(2)N-tert-butyl]Zr(NMe(2))(2) (Cp is cyclopentadienyl), [Zr(C(16)H(25)NSi)(C(2)H(6)N)(2)], in very good yield. Treatment of isodiCpHSiMe(2)NH-tert-butyl with Zr(NMe(2))(4) leads to the formation of a yellow solid that can be purified by sublimation. The single-crystal structure of the product shows the exo complexation of the isodicyclopentadienyl ligand to the Zr atom. The Cp portion of this ligand is bonded to the Zr atom in a eta(5) manner, with a …

Titanium isodicyclopentadienide hemimetallocenes for ethylene/styrene copolymerization

Abstract The syndiotactic polymerization of styrene with exo-[(η5-isodiCp)TiCl3] 1/methylalumoxane (MAO; isodiCp=isodicyclopentadienyl) was studied as well as the ethylene/styrene copolymerization with exo-[{η5:η1(N)-isodiCp(SiMe2Nt-Bu)}TiCl2] 2/MAO. These two catalytic systems are stable during polymerization. The half-sandwich titanocene 1 exhibits good syndiospecificity and average activity. The bridged half-sandwich amino complex 2 was found to incorporate styrene into polymer chains at 70 °C. Activity results decrease with increasing styrene concentrations.

Frontispiece: A Novel Cathode Material for Cathodic Dehalogenation of 1,1‐Dibromo Cyclopropane Derivatives

Syntheses and properties of some exo,exo-bis(isodicyclopentadienyl)titanium low-valent complexes

Abstract The paramagnetic compounds exo,exo-bis(η5-isodicyclopentadienyl)chlorotitanium(III) (3) and its analogue with trimethylsilyl-substituted isodicyclopentadienide (isodiCp) ligand (4), and the similar pair of diamagnetic exo,exo-bis(isodicyclopentadienyl)[η2-bis(trimethylsilyl)ethyne]titanium(II) complexes 5 and 6 were obtained by common reduction procedures from exo,exo-bis(isodicyclopentadienyl)titanium(IV) dichloride (1) and exo,exo-bis[η5-2-(trimethylsilyl)isodicyclopentadienyl]titanium(IV) dichloride (2), respectively. As indicated by ESR spectroscopy compound 3 is a dimer in the solid state and in frozen toluene glass but monomeric in toluene solution. Compound 4 is monomeric in…

A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane deriva…

Ethene/norbornene copolymerization with (isodicyclopentadienyl)titanium complex-MAO catalyst

Norbornene (NB) homopolymerization and ethene/NB copolymerizations with a silylene-bridged (isodicyclopentadienyl)(tert-butylamido)titanium dichloride-methylalumoxane (MAO) catalyst system were investigated. This catalytic system shows no efficiency towards NB homopolymerization but produces poly(ethene-co-norbornene)s. An increase in the initial NB feed content leads to a loss of copolymerization activity as well as NB copolymer incorporation. The structure of the isodicyclopentadienyl fragment (IsodiCp) has a strong limiting effect on comonomer incorporation possibilities.