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Decamethylchromocene [Cr(η5-C5Me5)2] reacted with cyclopentadienyltitanium trichlorides [Ti(η5-C5H5-nMen)Cl3] (n = 0–5) in toluene to precipitate yellow finely crystalline ion pairs [Cr(η5-C5Me5)2]+[Ti(η5-C5H5-nMen)Cl3]− (1–6). Evidence for the chromocenium cation and titanate anions was obtained by paramagnetic 1H NMR spectra of 1–6 in CD2Cl2. The resonance of the cation was invariant at δ 6.9 ppm (Δν1/2 ~ 0.4 kHz) whereas resonances of the titanate anions were shifting in response to the number of methyl groups (δ 10.5–8.4 ppm (CpMe) and δ 26.6–39.0 ppm (CpH)). The presence of toluene of crystallization in 1–6 was observed by 1H NMR spectra, and in the crystal structure of 6. Crystallization of 6 from tetrahydrofuran afforded solvent-free crystals of 6A. In crystal structures of both 6 and 6A the [Ti(η5-C5Me5)Cl3]– titanate anion possessed shorter Ti–Cg distances and longer Ti–Cl bonds than the neutral species.

Thermolysis of [TiMe 2 (η 5 -C 5 Me 4 Ph) 2 ] ( 4 ) at 145 °C for 5 h afforded the singly tucked-in paramagnetic titanocene [Ti(III)(η 5 -C 5 Me 4 Ph){η 5 :η 1 -C 5 Me 3 Ph(CH 2 )}] ( 9 ). In distinction to the singly tucked-in permethyltitanocene [Ti(III)(η 5 -C 5 Me 5 ){η 5 :η 1 -C 5 Me 4 (CH 2 )}] ( 1 ) which was found crystallographically disordered [J.M. Fischer, W.E. Piers, V.G. Young, Jr., Organometallics 15 (1996) 2410] the single crystal X-ray diffraction analysis of 9 afforded molecular parameters with nearly by one order better precision as measured by esd-values.

The [TiCl 2 (η 5 -C 5 Me 5 ) 2 ]/Mg excess /tetrahydrofuran system reacts with but-2-yne in excess to give paramagnetic (η 5 :η 1 -1,2,3,4-tetramethyl-5-(2,3,4,5-tetramethylpenta-2,4-dien-1,5-diyl-κC5)cyclopentadienyl)(η 5 -pentamethylcyclopentadienyl)titanium(III) ( 1 ) as the main product. The crystal structure of 1 shows a minimum steric hindrance between the methylated cyclopentadienyl ligands and non-coplanar conjugated double bonds in the C 5 tether.

Single tucked-in titanocene [Ti(η5-C5Me5)(η5:η1-C5Me4CH2)] adds to B(C6F5)3 to give the paramagnetic cationic complex [Ti(η5-C5Me5){η5-C5Me4CH2B(C6F5)3}] (1). Doubly tucked-in titanocene [Ti(η5-C5Me5){η3:η4-C5Me3(CH2)2}] reacts with B(C6F5)3 by one methylene group to give [Ti(η5-C5Me5){η5:η1-C5Me3(CH2)CH2B(C6F5)3}] (6). The crystal structure of 6 revealed that one hydrogen of the methylene group attached to boron agostically interacts with Ti(IV).

Bis{η5-(N,N-dimethylaminodimethylsilyl)tetramethylcyclopentadienyl}dichlorotitanium(IV), [TiCl2{η5-C5Me4(SiMe2NMe2)}2] (1), reacts with sulfane under cleavage of both Si–N and Ti–Cl bonds to give sulfido-tethered titanocene compound bis{η5-1,2,3,4-tetramethyl-5-(dimethylsilylsulfido-κS)cyclopentadienyl}titanium(IV), [Ti{η5-C5Me4(SiMe2S- κS)}2] (4), and dimethylamine hydrochloride as the byproduct. The crystal structure of compound 4 has been determined by single-crystal X-ray diffraction.

Paramagnetic complexes ansa-[Ti(C CCMe3){η5:η5-C5Me4SiMe2CH CHCH2CH2SiMe2C5Me4}] (1) and ansa-[Ti(OH){η5:η5-C5Me4SiMe2CH2CH CHCH2SiMe2C5Me4}] (2) were prepared by reactions of ansa-[Ti(III){η3:η5:η5-C5Me4SiMe2CHCHCHCH2SiMe2C5Me4}] (3) with t-butylethyne or water, respectively. The X-ray single crystal diffraction analysis of 1 and 2 showed that the cis-double bond is situated asymmetrically in the ansa-bridge of 1 whereas, in 2, the double bond is trans, and lies in the bridge centre. ESR and UV-near IR spectra indicated a weaker oxygen π-electron donation into the Ti–O bond of 2 compared to analogous methoxide ansa-[Ti(III)(OMe){η5:η5-C5Me4SiMe2CH2CH CHCH2SiMe2C5Me4}] (4) or decamethyltitanocene hydroxide (5).

Fully methylated titanocene hydroxide [Ti(OH) (η5-C5Me5)2] (1) was obtained by the reaction of single tucked-in decamethyltitanocene [Ti(η5-C5Me5){η5:η1-C5Me4(CH2)}] (2) with one equivalent of water dissolved in toluene. The X-ray single crystal diffraction of 1 revealed the bent Ti–O–H bonds (112(4)°) where the oxygen atom is only 0.038(4) A away from the Cg(1), Ti, Cg(2) (Cg – centroid of the cyclopentadienyl ring) plane, and the hydroxyl bond is directed to the cyclopentadienyl ring C(1–5). The Ti–O bond length (1.889(2) A) and energy of 1a1→b2 transition (6770(50) cm−1) indicate that the π-donation effect of the hydroxyl group is weaker compared to alkoxy groups.

The η3:η4-allyldiene-(η5-cyclopentadienyl)titanium(II) complex [Ti(η5-C5Me5){η3:η4-C5Me3(CH2)2}] (1) reacts with three molar equivalents of substituted propargylic alcohols FcCCCMe2(OH) (2a) and PhCCCH2OH (2b) at elevated temperature to give (η5-pentamethylcyclopentadienyl)titanium(IV) alkoxides [Ti(η5-C5Me5)(FcCCCMe2O-κO)3] (3a) and [Ti(η5-C5Me5)(PhCCCH2O-κO)3] (3b), respectively. The crystal structure of 3a has been determined by single-crystal X-ray diffraction.

Fully methylated η3:η4-allyldiene(η5-cyclopentadienyl)titanium(II) (1) reacts with alkynylketones RCCC(O)Me (R=SiMe3 (3a) and ferrocenyl (3b)) to give the expected products of the CO group insertion into one Ti–CH2 bond 4a and 4b, respectively. Compound 4a could not be isolated in pure form due to its high solubility; a minor product of two-fold addition (5) was isolated instead. Complex 5, formally [ 1 +2 3a ], was characterized as a monocyclopentadienyl bis(alkoxy)organyl complex, where the alkoxyorganyl ligand arises from CO insertion into one Ti–CH2 and the Ti–C(cyclopentadienyl) bonds. The structures of compounds 4b and 5 were determined by single-crystal X-ray diffraction.

Bis{η5-(N,N-dimethylaminodimethylsilyl)tetramethylcyclopentadienyl}dichlorotitanium(IV), [TiCl2{η5-C5Me4(SiMe2NMe2)}2] (1), easily undergoes hydrolytic cleavage of the Si–N bonds to give dimethylamine and {1,3-bis(η5-tetramethylcyclopentadienyl)-1,1,3,3-tetramethyldisiloxane}dichlorotitanium(IV), ansa-[TiCl2{(η5-C5Me4SiMe2)2O}] (2), in almost quantitative yields. The crystal structures of compounds 1 and 2 were determined by single-crystal X-ray diffraction.

The reduction of (C5Me4Ph)2TiCl2 by magnesium in tetrahydrofuran affords a mixture of the diamagnetic doubly tucked-in titanocene complex (C5Me4Ph)[C5Me2(CH2)2Ph]Ti (1), the paramagnetic trinuclear Ti–Mg–Ti hydride bridged complex [(C5Me4Ph)2Ti(μ-H)2]2Mg (2) and the paramagnetic binuclear titanocene hydride–magnesium hydride complex (C5Me4Ph)[C5Me4(o-C6H4)]Ti(μ-H)2Mg(THF)2 (3). The X-ray diffraction analysis of 3 revealed that the magnesium atom forms the σ-bond to the ortho-carbon atom of one of the phenyl rings and binds 2 molecules of THF.