Marvin D. Rausch

Organometallic π-complexes XII. The metalation of benzene and ferrocene by n-butyllithium-N,N,N′,N′-tetramethylethylenediamine

Abstract A detailed study has been made concerning the metalation of benzene and ferrocene by means of n-butyllithium + N,N,N′,N′-tetramethylethylenediamine in hexane and ethyl ether solution. Optimum conditions are described for the formation of phenyllithium and 1,1′-ferrocenylenedilithium, and the utility of these reagents inorganic and organometallic syntheses is demonstrated by their conversion in good yield to a variety of products. The n-butyllithium—diamine complex in hexane has been shown to metalate the methyl group of methyldiphenylphosphine in 54% yield.

Organometallic π-complexes : XX. The preparation of styrenetricarbonylchromium☆

Abstract The reaction of styrene and triamminetricarbonylchromium in refluxing dioxane gives styrenetricarbonylchromium in 50–65% yield. The complex can also be synthesized in 83% yield via a Wittig reaction involving benzaldehydetricarbonylchromium. Catalytic hydrogenation of styrenetricarbonylchromium produces ethylbenzenetricarbonylchromium, which has likewise been prepared directly from ethylbenzene and triamminetricarbonylchromium. Spectral properties and polymerization reactions of styrenetricarbonylchromium are discussed.

The isolation, characterization and synthetic utility of several solid organolithium compounds

Abstract Pentachlorophenyllithium and ferrocenyllithium have been isolated and characterized as relatively air-stable solids. The chemical reactivity of these organo-lithium compounds has been investigated, and several carbene complexes of chromium and tungsten have been prepared. Pentachlorophenyllithium adds to furan and therefore represents a solid benzyne precursor. 1,1′-Dilithioferrocene · 2TMEDA, ferrocenyllithium · TMEDA, and 2-lithio[(dimethylamino)methyl]ferrocene were isolated and characterized as air-sensitive solids. An attempted formation of 2,2′-dilithiobiphenyl from 2,2′-dibromobiphenyl and n-butyllithium yielded a mixture of ca. 80% of this dilithium reagent and ca. 20% of 2-bromo-2′-lithiobiphenyl.

Alkyl-substituted indenyl titanium precursors for syndiospecific ziegler-natta polymerization of styrene

A variety of 1- and 3-substituted alkylindenes (R = H, Me, Et, tert-butyl, Me3Si) as well as 2-methylindene and 3-(methylthio)indene have been prepared in good yields. The substituted indenes were converted into trimethylsilyl derivatives via reactions of intermediate organolithium complexes with chlorotrimethylsilane. The corresponding titanium complexes, (R-Ind)TiCl3, were synthesized in excellent yield from reactions of the trimethylsilyl derivatives with TiCl4. The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. Activities increased in the order: Cp < H4 Ind < Ind < 1-(Me)Ind <2-(Me)Ind. A steep drop in activity was observed when R = Et, tert-butyl, and Me3Si, corresponding to an increase in the steric bulk of the substituent in the catalyst precursor. 1-(MeS)IndTiCl3 was found to be ineffective as a styrene polymerization catalyst. Syndiospecificities of the titanium complexes were generally very good (65–98%).

The formation and molecular structures of (η5-C5H5)3Y · OC4H8 and (η5-C5H5)3La · OC4H8

Abstract A reaction between YCl 3 and excess sodium cyclopentadienide in THF solution followed by crystallization from this solvent affords (η 5 -C 5 H 5 ) 3 Y · OC 4 H 8 in 68% yield. The corresponding lanthanum complex (η 5 -C 5 H 5 ) 3 La · OC 4 H 8 can be obtained from LaCl 3 and C 5 H 5 Na in 76% yield via a similar procedure. The products have been characterized by their proton NMR and mass spectra, and by single crystal X-ray diffraction investigations. (η 5 -C 5 H 5 ) 3 Y · OC 4 H 8 [η 5 -C 5 H 5 ) 3 La · OC 4 H 8 ] crystallizes in the monoclinic space group P 2 1 / n [ P 2 1 / n ] with unit cell parameters a  8.170(3) [8.371(4)], b  24.594(5) [24.636(5)], c  8.260(3) [8.454(3)] A, β  101.32(3) [101.84(3)]°, D c  1.45 [1.58] g cm -3 for Z  4 [4]. Least-squares refinement has led to a final R value of 0.041 [0.088] based on 1992 [2193] independent observed reflections. The THF molecule is coordinated to the yttrium [lanthanum] atom at a YO(LaO) bond length of 2.451(4) [2.57(1)] A. The YC(Cp)[LaC(Cp)] bond distances average 2.71(3) [2.82(4)] A. The title compounds are isostructural with (η 5 -C 5 H 5 ) 3 Gd · OC 4 H 8 .

Preparation, characterization and reactivity of Cp2M(PMe3)2 complexes (M = Ti, Zr): the molecular structure of Cp2Zr(PMe3)2

Abstract The reduction of Cp2MCl2 (M = Ti, Zr) with magnesium in THF in the presence of PMe3 affords the complexes Cp2M(PMe3)2 in high yields. These compounds lose one or both PMe3 ligands under very mild conditions. Cp2Ti(PMe3)2 reacts readily with CH3I, CH3C(O)Cl, PhSSPh, Me2PCH2CH2PMe2, CO, RCN (R = Me, t-Bu) or (RN)2S (R = t-Bu, Me3Si) to give the corresponding titanocene products. The structure of Cp2Zr(PMe3)2 has been determined by X-ray diffraction; the structural parameters are similar to those of the titanium analog Cp2Ti(PMe3)2 except that the Zr-P and Zr-C distances are longer.

Photochemical investigations of di-η5-cyclopentadienyldimethyltitanium and deuterated analogs

Abstract The photolysis of (η 5 -C 5 H 5 ) 2 Ti(CH 3 ) 2 in hydrocarbon solvents results in cleavage of the carbon—titanium σ-bonds and formation of methane and black titanocene. Deuteration studies have shown that other methyl substituents as well as the cyclopentadienyl rings can serve as the source of hydrogen in the formation of methane. Chemical reactions with HCl, Br 2 , and CO, as well as spectroscopic and solution molecular weight studies indicate that photochemically-generated titanocene is probably an oligomeric material, made up of (η 5 C 5 H 5 ) 2 Ti and (η 1 : η 5 -C 5 H 4 )T 2 units connected by extended metal—metal bonds. Photolysis of (η 5 -C 5 H 5 ) 2 Ti(CH 3 ) 2 in the presence of CO leads directly to (η 5 -C 5 H 5 ) 2 Ti(CO) 2 in good yield, whereas photolysis in the presence of diarylacetylenes produces titanacycle analogues along with products derived from insertion of the acetylene into the TiCH 3 bond.

The formation and reactions of (η5-carboxycyclopentadienyl)dicarbonylcobalt

Abstract A reaction between sodium cyclopentadienide and dimethyl carbonate in THF solution produces sodium carbomethoxycyclopentadienide in high yield. The analogous carbethoxy derivative can also be readily prepared starting with diethyl carbonate. Carbomethoxycyclopentadienylthallium has been prepared by cracking carbomethoxycyclopentadiene dimer and passing the unstable monomer into an aqueous mixture of thallium(I) chloride and potassium hydroxide. Reactions of these reagents with mixtures of dicobalt octacarbonyl and iodine in THF solution afford moderate yields of the respective products (η5-carbomethoxycyclopentadienyl)dicarbonylcobalt and (η5-carbethoxycyclopentadienyl)dicarbonylcobalt. (η5-Carboxycyclopentadienyl)dicarbonylcobalt is obtained in 67–74% yield by treatment of either ester with potassium hydroxide in aqueous ethanol followed by acidification. A reaction between this acid and oxalyl chloride in benzene solution produces (η5-chloroformylcyclopentadienyl)dicarbonylcobalt in 67% yield, and the latter reacts readily with ammonia and with aniline to form the respective amide and anilide derivatives. The acid chloride also reacts with ferrocene and aluminum chloride under Friedel-Crafts conditions to afford the bimetallic product (η5-ferrocenoylcyclopentadienyl)dicarbonylcobalt. The IR and 1H NMR spectra of these new functionally-substituted derivatives of (η5-cyclopentadienyl)dicarbonylcobalt are discussed.

Polymerization with TMA‐protected polar vinyl comonomers. II. Catalyzed by nickel complexes containing α‐diimine‐type ligands

α-Diimine Ni complexes (7, 8) were used as catalyst precursors with MAO in co- and terpolymerization of ethylene/propylene/α-olefins with OH and COOH functional groups. Trimethylaluminium was used to protect the functional group of polar monomers. The presence of 5-hexen-1-ol seems to have no effect on the polymerization rate at all for the N,N′-bis(2,6-diisopropylphenyl) derivative 8 but caused activity decreases of about fivefold in copolymerization and around two times in terpolymerization for the N,N-dimesityl derivative 7. The effect levels off at higher polar comonomer concentration. This system, (7)/MAO, also incorporates well both 10-undecen-1-ol and 10-undecen-1-oic acid. The activities obtained with these α-diimine Ni complexes in co- and terpolymerization are three to twenty times higher than those obtained with group 4 Cp based complexes especially at concentrations of polar monomer in the feed higher than 80 mM.

Polymerization with TMA‐protected polar vinyl comonomers. I. Catalyzed by group 4 metal complexes with η5‐type ligands

This paper describes the use of several kinds of group IV Cp based catalyst systems, in the synthesis of co- and terpolymers of ethylene, propylene and α-olefins endowed with OH and COOH functional groups. The hydroxy monomers used were 5-hexen-1-ol (4) and 10-undecen-1-ol (5) and the carboxy monomer was 10-undecen-1-oic acid (6). The three catalyst systems used were the C 2 symmetric ansa-zirconocene (1) the in-site titanium complex (2) and the non-rigid zirconocene (3), all activated by methylaluminoxane. Trimethylaluminium was used to protect the functional group of polar monomers. The first two catalyst systems suffer similar activity loss in the presence of polar monomer whereas the third one exhibited better tolerance toward the hydroxyolefins. NMR and FTIR spectroscopies were used to characterize the polymerization products. All three catalyst systems afforded functionalized co- and terpolymers by direct polymerization of ethylene/propylene/hydroxy-a-olefins but only the catalyst system (1)/MAO displays appreciable activities for direct polymerization of ethylene, propylene and carboxy-α-olefins.