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Single and double tucked-in titanocenes react with excess CO2 by insertion into their Ti–CH2 bonds to form carboxylate-tethered species and subsequently new dimeric carbodiolates.

Reduction of ansa-titanocene dichlorides [X(η5-C5H4)2TiCl2] (X = SiMe2 (1) and CMe2 (2)) in tetrahydrofuran (THF) by preactivated magnesium in the presence of bis(trimethylsilyl)acetylene (BTMSA) yielded complexes [X(η5-C5H4)2Ti(η2-BTMSA)] (X = SiMe2 (3) and CMe2 (4)). The prolonged action of excess magnesium and BTMSA resulted in the formation of ansa-titanium-magnesium complexes [μ-X{(η5-C5H4)Ti(η2-SiMe3C≡CSiMe3)2}{(η5-C5H4)Mg(THF)}] (X = SiMe2 (5) and CMe2 (6)), which had their metals bounded via the ansa-ligand and ionic bonding between magnesium and the BTMSA ligands. Compounds 5 and 6 easily isomerized to 5a and 6a through rotation of their {(C5H4)Mg(THF)} moiety around the ansa- X–C bond. This rotation canceled the interaction of magnesium with the BTMSA ligands, which resulted in a large high-field shift of acetylenic carbon resonances. The geometry of both structures optimized by Density Functional Theory (DFT) computations together with the good correlation of computed magnetic shieldings and experimental 13C NMR shifts of 5 and its isomer 5a approved the above isomerization. The simultaneous ionic bonding of Mg2+ to the cyclopentadienyl ligand, which is η5-coordinated to the {Ti(η2-BTMSA)2} moiety in 5a got also confirmed by computational results. Reduction by magnesium was used to obtain Ti(III) dimers of ansa-titanocene acetylides [{X(η5-C5H4)2Ti (μ-η1:η2-C≡CSiMe3)}2] (X = SiMe2 (7) and X = CMe2 (8)) via redox splitting of 1,4-bis(trimethylsilyl)buta-1,3-diyne (BSD) by transient Ti(II) titanocene. The thermally stable Ti(II) compounds 3 and 4 were also shown to react with BSD yielding respectively 7 and 8. The reduction of 1 and 2 with magnesium in THF afforded Ti(III) monochloride dimers [{ansa-X(η5-C5H4)2Ti(μ-Cl)}2] (X = SiMe2 (10); CMe2 (11)), which in contrast to the non-ansa dimer [(η5-C5H5)2Ti(μ-Cl)}2] were silent in toluene glass EPR spectra. No evidence of obtaining quadruply bridged dititanium complexes capped with the ansa-ligands was encountered among crystal structures of 7–11, even though the total energy of optimized molecules 7 and 10 and their capped congeners differed by more than 45 kJ/mol, favouring the capped isomers in both cases.

We describe the occurrence and possible origin of rare beds 1–10cm thick and containing 20–70% of crandallite, a Ca-Al phosphate enriched in Sr and Ba, found within otherwise monotonous clay-rich lacustrine sediments of the Most Basin in the Central-European Neogene Ohře Rift system. The beds were formed at ca. 17.31, 17.06, and 16.88Ma, while the entire suite of monotonous clays of the Libkovice Member was deposited between 17.46 and 16.65Ma. Trace-element and organic geochemistry, Ar-Ar geochronology and C-O-Sr isotope systematics are used to infer their source and processes leading to their formation. The most enigmatic aspect of the formation of the crandallite beds is the removal of a huge amount of phosphorus from its biogenic cycle in the lacustrine system, which was otherwise stable for ca. 0.8My. Formation of detritus-poor crandallite beds could result from some exceptional environmental disruptions that hindered transport of fine clastic material to the basin floor. Silicic volcanic activity in the area of the Pannonian Basin could have triggered this disruption. Crandallite could provide evidence of long-lasting droughts and acidification of the exogenic environment, as they are roughly coeval with the onset of the Miocene Climatic Optimum at ca. 17.0Ma.

A series of Miocene fossil resin from the northwest part of the Czech Republic, called duxite, has been analyzed by elemental, microscopic, gas chromatography (GC/MS), pyrolysis-gas chromatography, Fourier Transform infrared (FTIR), and Raman techniques. The set of samples consisted of museum, contemporary and artificially altered samples. The results of GC/MS revealed fine variances in chemical structure among the samples, which could be attributed to the geologic paleosituation during resin deposition, as was verified by alteration of a sample under different conditions. Sesquiterpenes, including α-cedrene and cuparene, were identified in sample extracts and sample pyrolysates together with diterpenoid members abietanes, pimaranes, and dehydroabietanes. The distribution and intensity of functional groups of FTIR spectra also confirmed that the duxite samples were fossilised exudates from a member of the Cupressaceae conifer family. Raman spectra supported this record indicating aromatic character of duxite and higher maturity of the samples. The chemical composition indicated that duxite is a member of Class IV resins of the fossil resin classification system. Members of this group do not have a polymeric structure. This nonpolymerizable behaviour was confirmed by their excellent solubility in an organic solvent and the low softening point of the material. Our results therefore provide a valuable insight into the duxite-producing process and its potential for evaluating the geological environment and diagenetic conditions.

The singly tucked-in titanocene [(η5-C5Me5)TiIII{η5:η1-C5Me4(CH2)}] (1) reacted with one equivalent of 1-tert-butylpropyne to yield the propenyl-tethered regioisomer [(η5-C5Me5)Ti(η5:η1-C5Me4CH2C(t-Bu) = κCMe)] (3). The exclusive formation of paramagnetic 3 was proved experimentally and steric reasons were clarified by DFT calculation of transition state which involves both π-systems on the alkyne for bonding interaction with the metal and with sp2 carbon atom of exomethylene group of 1. The obtained compound 3 is by 40 kJ/mol lower in energy than its hypothetical isomer having t-Bu group on Cα of the tether.

Reactions following the addition of dihydrogen under maximum atmospheric pressure to bis(trimethylsilyl)acetylene (BTMSA) complexes of titanocenes, [(η5-C5H5-nMen)2Ti(η2-BTMSA)] (n = 0, 1, 3, and 4) (1A-1D), and zirconocenes, [(η5-C5H5-nMen)2Zr(η2-BTMSA)] (n = 2-5) (4A-4D), proceeded in diverse ways and, depending on the metal, afforded different products. The former complexes lost, in all cases, their BTMSA ligand via its hydrogenation to bis-1,2-(trimethylsilyl)ethane when reacted at 80 °C for a prolonged reaction time. For n = 0, 1, and 3, the titanocene species formed in situ dimerised via the formation of fulvalene ligands and two bridging hydride ligands, giving known green dimeric titanocenes (2A-2C). For n = 4, a titanocene hydride [(η5-C5HMe4)2TiH] (2D) was formed, similarly to the known [(η5-C5Me5)2TiH] (2E) for n = 5; however, in contrast to this example, 2D in the absence of dihydrogen spontaneously dehydrogenated to the known Ti(iii)-Ti(iii) dehydro-dimer [{Ti(η5-C5HMe4)(μ-η1:η5-C5Me4)}2] (3B). This complex has now been fully characterised via spectroscopic methods, and was shown through EPR spectroscopy to attain an intramolecular electronic triplet state. The zirconocene-BTMSA complexes 4A-4D reacted uniformly with one hydrogen molecule to give Zr(iv) zirconocene hydride alkenyls, [(η5-C5H5-nMen)2ZrH{C(SiMe3)[double bond, length as m-dash]CH(SiMe3)}] (n = 2-5) (5A-5D). These were identified through their 1H and 13C NMR spectra, which show features typical of an agostically bonded proton, [double bond, length as m-dash]CH(SiMe3). Compounds 5A-5D formed equilibria with the BTMSA complexes 4A-4D depending on hydrogen pressure and temperature.

Two novel half-sandwich Ti complexes, both incorporating two adamantoxy (OAd) ligands coordinated to their central atoms were synthesized. The complexes were characterized by 1 H, 13 C, 19 F NMR, EI-MS and IR spectroscopy and by single-crystal X-ray diffraction. In both complexes, the coordination environment is pseudo-tetrahedral and is assembled of two O-coordinated adamantoxy and one η 5 -coordinated permethylcyclopentadienyl ligand. The fourth ligand in complex 1 is a methyl group coordinated through a regular σ-bond, whereas in complex 2 the same coordination site is occupied by the methyl group of the balancing (C 6 F 5 ) 3 BMeˉ anion. DFT computations complemented with NBO analyses of 2 have unveiled, that in addition to the electrostatic interactions occurring between the half-sandwich titanocene moiety and the anionic ligand, delocalization of one methyl C H bond into the available acceptor orbital on the central atom takes place. AIM analyses of 2 have revealed the presence of a Bond Critical Point between the metal atom and the anionic methyl group. These results prove foundation for the description of 2 as a zwitterionic complex coupled with a concurrent Ti⋯C H agostic interaction in its molecule. The comparison of 2 with its analogous complex equipped with two O t -Bu ligands instead of both OAd has suggested only a minor change in the extent of the agostic interaction, despite significant geometric differences between the two complexes.

Sunlight photolysis of the triplet state (S = 1) dititanium compound 1 induced its rearrangement to diamagnetic 2, which was a molecule containing two hydrogens less. The cage structure of 2 was determined by single crystal X-ray diffraction and was corroborated fully by 1H and 13C NMR spectra that identified three simple bridging moieties — a hydrogen atom, a methine carbon and a methylene carbon. Its extremely short Ti−Ti distance 2.7537(7) A causes a strong distortion of the bridging fulvalene ligand, which becomes η5- bonded to one Ti(IV) and connected by two σ-bonds from nearest carbon atoms of its other ring to the other Ti(IV) of 2. Other photolytical byproducts in very minor amounts were also isolated, which differed from 2 by the absence of one bridging moiety: compound 4 lacked the methine group and compound 5 had no bridging hydrogen. In the latter cases, the Ti−Ti distance fell in the range 3.2077(8) – 3.5543(12) A and the fulvalene ligand was coordinated in the common µ-η5: η5-mode to both titanium atoms. The octamethylfulvalene ligands in 4 and 5 had their ring planes rotated mutually by about 40° in order to relieve the steric hindrance between their methyl groups. The thermally robust µ-oxo complex 3 obtained from reacting 2 with water showed a very similar structure.

1H NMR studies of reactions of titanocene [Cp*2Ti] (Cp* = η5-C5Me5) and its derivatives [Cp*(η5:η1-C5Me4CH2)TiMe] and [Cp*2Ti(η2-CH2CH2)] with excess dihydrogen at room temperature and pressures lower than 1 bar revealed the formation of dihydride [Cp*2TiH2] (1) and the concurrent liberation of either methane or ethane, depending on the organometallic reactant. The subsequent slow decay of 1 yielding [Cp*2TiH] (2) was mediated by titanocene formed in situ and controlled by hydrogen pressure. The crystalline products obtained by evaporating a hexane solution of fresh [Cp*2Ti] in the presence of hydrogen contained crystals having either two independent molecules of 1 in the asymmetric part of the unit cell or cocrystals consisting of 1 and [Cp*2Ti] in a 2 : 1 ratio. Hydrogenation of alkyne complexes [Cp*2Ti(η2-R1CCR2)] (R1 = R2 = Me or Et) performed at room temperature afforded alkanes R1CH2CH2R2, and after removing hydrogen, 2 was formed in quantitative yields. For alkyne complexes containing bulkier substituent(s) R1 = Me or Ph, R2 = SiMe3, and R1 = R2 = Ph or SiMe3, successful hydrogenation required the application of increased temperatures (70–80 °C) and prolonged reaction times, in particular for bis(trimethylsilyl)acetylene. Under these conditions, no transient 1 was detected during the formation of 2. The bulkier auxiliary ligands η5-C5Me4tBu and η5-C5Me4SiMe3 did not hinder the addition of dihydrogen to the corresponding titanocenes [(η5-C5Me4tBu)2Ti] and [(η5-C5Me4SiMe3)2Ti] yielding [(η5-C5Me4tBu)2TiH2] (3) and [(η5-C5Me4SiMe3)2TiH2] (4), respectively. In contrast to 1, the dihydride 4 did not decay with the formation of titanocene monohydride, but dissociated to titanocene upon dihydrogen removal. The monohydrides [(η5-C5Me4tBu)2TiH] (5) and [(η5-C5Me4SiMe3)2TiH] (6) were obtained by insertion of dihydrogen into the intramolecular titanium-methylene σ-bond in compounds [(η5-C5Me4tBu)(η5:η1-C5Me4CMe2CH2)Ti] and [(η5-C5Me4SiMe3)(η5:η1-C5Me4SiMe2CH2)Ti], respectively. The steric influence of the auxiliary ligands became clear from the nature of the products obtained by reacting 5 and 6 with butadiene. They appeared to be the exclusively σ-bonded η1-but-2-enyl titanocenes (7) and (8), instead of the common π-bonded derivatives formed for the sterically less congested titanocenes, including [Cp*2Ti(η3-(1-methylallyl))] (9). The molecular structure optimized by DFT for compound 1 acquired a distinctly lower total energy than the analogously optimized complex with a coordinated dihydrogen [Cp*2Ti(η2-H2)]. The stabilization energies of binding the hydride ligands to the bent titanocenes were estimated from counterpoise computations; they showed a decrease in the order 1 (−132.70 kJ mol−1), 3 (−121.11 kJ mol−1), and 4 (−112.35 kJ mol−1), in accordance with the more facile dihydrogen dissociation.

Solutions of permethylcyclopentadienyl-tethered titanium(IV) chlorides incorporating one double bond in their tethers were exposed in glass vessels to sunlight, which triggered their photolytical reactions providing mixtures of products. Although the formation of several different products was apparent from 1H NMR spectra, only a single product could be identified in the crude reaction mixtures. This product was dicyclopentadiene [C10Me10], which arose from the recombination of the generally photodissociated C5Me5 radical. Amongst products that contained titanium, three complexes (3a, 3b and 4a) could be isolated after employing fractional crystallization and these complexes were characterized. The mechanism of 3a formation involves photodissociation of one η5-C5Me5 ligand from the parent complex, complemented by chlorine abstraction from another reactant molecule. Complexes 3b and 4a become formed via tether rearrangement, which starts with dissociating the tether Ti–C bond and is followed by rotating the tether, reattaching it subsequently through its available radical terminus.

The permethylcyclopentadienyl diphenylsilylene-bridged titanium constrained geometry complex [TiCl2{η5-C5Me4(SiPh2NCMe3-κN)}] (2) was synthesised following the common synthetic route and subsequently characterised by spectral analyses and by single-crystal X-ray diffraction. The comparison of its solid-state structure with that of the parent dimethylsilylene CGC complex [TiCl2{η5-C5Me4(SiMe2NCMe3-κN)}] (1) revealed only negligible geometry differences between their cyclopentadienyl centroid-Ti-N-Si skeletons. A significantly different positioning was however observed for the amine tBu substituent of the DFT-optimised methyl-substituted cationic catalytical species (1a, 2a), which are supposed to be generated from 1 and 2 in the presence of methylaluminoxane (MMAO). A lower ethylene polymerisation activity of 2-MMAO system compared to that of 1-MMAO is compatible with the higher steric congestion at the metallic centre due to the tBu ligand becoming rotated more into the open space in 2b. This arrangement aggravates monomer access throughout the catalytical process and decreases the coordination unsaturation of the central atom through the formation of auxiliary agostic interaction.

A thermally robust triple-decker complex [bis(η5-pentamethylcyclopentadienyltitanium)-μ-(η4:η4-1,2,4,5-tetrakis(trimethylsilyl)cyclohexa-1-4-diene-3,6-diyl)] (3) was obtained in 4% yield by thermolysing Cp*TiMe3 in the presence bis(trimethylsilyl)acetylene (BTMSA). The solid-state structure of centrosymmetric 3 features rather long all C–C bonds in the nearly planar bridging ligand (1.4720(14)–1.4896(15) A) and a short distance of its least-square plane to the titanium atoms (1.7381(5) A). Computational results revealed the bonding of the central ligand to be accomplished through back-bonding of its two CC bonds and through the simultaneous generation of two σ-Ti–C(H) bonds. Based on CASSCF and CASPT2 results, the molecule acquires several electronic configurations simultaneously, which hinders its representation by one single Lewis structure. Apart from being coordinated to the central ligand, the metal atoms are involved in a direct Ti–Ti bonding by the formation of one σ- and two δ-bonds between them. The bond order of this Ti–Ti overlap shows only a slight decrease upon electronic excitation. The presence of ionic contribution to the bonding of the central ligand is manifested by the charge −1.4e summed on the carbon atoms of the bridging ring. Based on computational results, the spin multiplicity of the ground state is singlet, while the first low lying excitation state is triplet. This is in agreement with the absence of EPR signal in either toluene solution and glass, and with slight downfield shifts of broadened 1H NMR signals of SiMe3 and Cp* methyl groups observed with increasing temperature.

Bis{(diphenylvinylsilyl)tetramethylcyclopentadienyl}titanium dichloride [TiCl2{η5-C5Me4(SiPh2CH=CH2)}2] (1) is reduced with a half molar equivalent of magnesium to the monochloride ([TiCl{η5-C5Me4(SiPh2CH=CH2)}2] (2), whereas one molar equivalent of magnesium affords the titanocene [Ti{η5-C5Me4(SiPh2CH=CH2)}{η5:η2-C5Me4(SiPh2CH=CH2)}] (3) stabilized by η2-coordination of one of the two vinyl groups to titanium(II). In the presence of excess magnesium, the vinyl moieties of 3 undergo intramolecular coupling to afford the ansa-titanocene [Ti(η5:η5:η2-C5Me4SiPh2CH=CHCH2CH2SiPh2C5Me4)] (4) possessing the η2-coordinated double bond in lateral position of its ansa-chain. The symmetrical ansa-titanocene [Ti(η5:η5:η2-C5Me4SiPh2CH2CH=CHCH2SiPh2C5Me4)] (5) was not obtained although its DFT-calculated energy is only slightly higher than that of 4. It is considered that transient 5 gives rise to non-identified tar-like by-products which inherently accompany the formation of 4.

Thirty samples of the lacustrine sediments from three localities of the Most Basin including coal samples were studied by petrological and organic geochemical methods. The consistent results indicate the relatively stable surface development of the sediments in the environment of the Holesice, Lom and Osek Members. Biological material with contribution of microbial activity participated in the storing, which led to the formation of clayey coal. In the results of the chemical composition dominated sesqui-, diand triterpene compounds. Completely different sediments of Libkovice Member contained low proportions of small organic particles dispersed in the sediment. In the extracts of these samples prevailed hopanes, perylene and sulphur after the action of microorganisms. The base of the organic fraction also formed remains of terrestrial plants and liptinite macerals, especially alginite, liptodetrinite and bituminite that are typical for lacustrine sediments.

Titanocene hydride [Cp*2TiH] (Cp* = η5-C5Me5) (1) readily inserts simple internal alkynes R1C≡CR2 into its Ti–H bond, yielding titanocene alkenyl Ti(III) compounds of two structural types. The less sterically congested products [Cp*2Ti(R1C═CHR2)] (2a–e) contain a σ1-bonded alkenyl group, whereas the products bearing at least one trimethylsilyl substituent and other bulky substituents (R1 = SiMe3; R2 = SiMe3, 4a; CMe3, 4b; and Ph, 4c) possess a remarkable Ti–H agostic bond of the σ1-bonded alkenyl group. This feature is consistent with solution EPR spectra of 4a–4c showing a doublet due to coupling of the hydrogen nucleus with the Ti(III) d1 electron. Compound 1 reacts with one molar equivalent of conjugated buta-1,3-diynes (RC≡C)2 to give η3-butenyne complexes (R = SiMe3, 5a; CMe3, 5b). The Ti(III) complexes 2a–2e and 5a and 5b were oxidatively chlorinated with PbCl2 to give Ti(IV) chloro-alkenyl complexes [Cp*2TiCl(R1C═CHR2)] 3a–3e and chloro-alkenynes 6a and 6b, respectively. 1H and 13C NMR spectra of 3...

New titanocene dihydrosulfide compounds [(C 5 Me 4 CH 2 Ph) 2 Ti(SH) 2 ] ( 6 ) and [(C 5 Me 4 t -Bu) 2 Ti(SH) 2 ] ( 7 ) were obtained by addition of hydrogen sulfide to the corresponding doubly tucked-in titanocenes, and titanocene hydrosulfide compounds [(C 5 Me 4 CH 2 Ph) 2 TiSH] ( 8 ) and [(C 5 Me 4 t -Bu) 2 TiSH] ( 9 ) by H 2 S-induced protonolysis of σ-Ti–C bonds in [(η 5 -C 5 Me 4 CH 2 Ph)Ti(III)(η 5 :η 1 -C 5 Me 4 CH 2 - o -C 6 H 4 )] and [(C 5 Me 4 t -Bu)Ti(III)(η 5 :η 1 -C 5 Me 4 CMe 2 CH 2 )], respectively. The crystal structures of 6 , 8 , and 9 and electronic absorption spectra of 6 – 9 in hexane solution highly resemble those of corresponding [Cp* 2 Ti(SH) 2 ] ( 1 ) and [Cp* 2 TiSH] ( 2 ), however, compounds 6 and 7 strongly differ in their sensitivity to sunlight mutually and with respect to 1 . The sunlight photolysis of 6 in toluene proceeded similarly to the process described previously for 1 except that about three times longer exposition (300 h) was required to obtain the cyclopentadienyltitanium sulfide cage cluster [{(C 5 Me 4 CH 2 Ph)Ti} 4 S 6 ] ( 10 ) in 48% yield. In contrast, compound 7 photo-decomposed very efficiently to give compound 9 as the only isolated titanium-containing product in 87% yield. The formation of 10 can be accounted for the redox elimination of the cyclopentadiene followed by elimination of hydrogen sulfide in intramolecular condensation reaction whereas the formation of 9 requires the dissociation of SH radicals. Both the processes were recognized by Rosenthal and Beweries to concur in photodecomposition of [Cp* 2 Ti(OH) 2 ].

Five fossil resins from various localities in the Czech Republic were investigated. To arrive at more detailed description of the resins, pyrolysis-gas chromatography/mass spectrometry with derivatisation using tetramethylammonium hydroxide, gas chromatography-mass spectrometry, and micropetrography were applied. The content of organic macerals, composition of biomarkers in the solvent extracts and in the pyrolysates have been determined and compared to amber samples. The analyses clearly indicate that all resins belong to the Class Ib type derived from regular labdane structures that lacked succinic acid. The presence of labdane type diterpenoids and the absence of plant triterpenoids in the resin point to a conifer (gymnosperm) source which contrasts with the angiosperm source of Sarawak amber from Malaysia. According to their chemical composition, all Czech resins can be assigned to the Cupressaceae family. There was an obvious difference between a Duxite sample (Miocene) and other resins that could be attributed to deposition inside wood, which did not allow degradation of the resin.

Bis(decamethyltitanocene) oxide, [(Cp*2Ti)2O] (1; Cp* = η5-C5Me5) has been obtained as a yellow crystalline solid after reacting equimolar amounts of the hydride [Cp*2TiH] and the hydroxide [Cp*2Ti(OH)]. The solid-state structure of 1 revealed a linear Ti–O–Ti arrangement and a mutual, nearly perpendicular orientation of the bent-sandwich titanocene moieties; the length of both Ti–O bonds amounted to 1.9080(3) A. A unique structural feature was a close-to-eclipsed conformation of the cyclopentadienyl ligands, attributed to the high steric congestion of 1. The molecule in toluene glass exhibited a triplet state EPR spectrum of rhombic symmetry, having zero field splitting D = 0.02159 cm–1 and E = 0.00230 cm–1. The 1H NMR spectrum of 1 in toluene-d8 displays a paramagnetic resonance at δ 4.3 ppm (Δν1/2 ≈ 270 Hz). Compound 1 reacts with 1 molar equiv of water to give [Cp*2Ti(OH)]. In CD2Cl2, 1 is oxidized to yield the major product [(Cp*TiCl2)2O] and minor product [{Cp*Ti(Cl)O}3].

Sunlight photolysis of decamethyltitanocene dihydrosulfide [Cp*2Ti(SH)2] (1, Cp* = η5-C5Me5) in toluene affords the titanium sulfide clusters [(Cp*Ti)6(μ3-S)8] (4) and [(Cp*Ti)4(μ3-S)3(μ2-S)3] (5), the former in very low yield and the latter in good yield. The crystal structures of both compounds are toluene solvates and are based on a nearly regular titanium octahedron for 4 and a trigonal pyramid for 5. The [(Cp*Ti)3(μ3-S)(μ2-S)3] (6) complex isolated in a trace amount from the photolysis of 1 in hexane could be a precursor of 4. A plausible mechanism for the formation of 5 and 6 follows a mechanism recently proposed for photolysis of [Cp*2Ti(OH)2] by U. Rosenthal et al.

article i nfo Numerous coalified tree stumps remained preserved in-situ in the so-called "Stump Horizon" (the palaeontologic horizon No.31), which represents clayey overburden of themain coal seam in the Bilina open cast mine in the Most Basin (Czech Republic). The petrological and chemical composition, palaeobotanical origin and preservation of 24 selected tree stumps were studied by optical and scanning electron microscopy and gas chromatography-mass spectrometry (GC-MS). Composition of the fossil wood is dominated by ulminite, particularly texto-ulminite B. Textinite forms up to 38 vol.% in the decomposed tree stumps. Corpohuminite dominates in bark and root tissues. Partly gelified and deformed woody tissuescontain both corpohuminite and resinite fillings.Randomreflectance of ulminite ranges from 0.33% to 0.39% and carbon content from 49 wt.% to 78 wt.%. Samples represent pure woody material with small admixtures of clay minerals, siderite, and very rare pyrite. Observations by scanning electron microscopy revealed various levels of deformed secondary xylem with more or less swollen cell walls, conspicuous tracheids, uniseriate rays of a different height, and round or cylinder-like resin or corpohuminite bodies. According to our results and other published data the wood might belong to Glyptostroboxylon and Taxodioxylon genera that are supposed to belong to Glyptostrobus and Quasisequoia plants respectively, representatives of the coniferous family Cupressaceae. The biomarker composition in the extracts of the fossil wood includes sesquiterpenoids (α-cedrane, drimane, eudesmane), diterpenoids (abietane, fichtelite, 16α(H)-phyllocladane) and their degraded compounds. The terpenoids are derived from precursors produced by the source plants and microorganisms. The terpenoid signatures support a relationship to the Cupressaceae family with input of microbial species. These characteristics were identical for all studied samples. Significant variations have been observed in sesquiterpenoid α-cedrane and diterpenoid 16α(H)-phyllocladane contents.

Exposures in the Bilina opencast mine provide a direct evidence that the 3.5 m thick upper bench of the Main Seam in the Most Basin passes over a distance of about a kilometre into a hundred metres thick equivalent of clastic deltaic sediments with Gilbert-type mouth bars and thus clearly corroborates the co-existence of lacustrine delta–mire system. Deposition of the delta and the upper bench of the Main Seam were affected by five short-term lacustrine incursions, possibly related to tectonic subsidence before final lacustrine transgression took place. Between the temporary lacustrine incursions, delta mouth bars prograded into an extensive mire being separated only by a shallow compaction lake along mouth bars foreland. However, most clastics, introduced from delta were caught by dense vegetation in a narrow proximal zone of mire and did not affect more distal parts of relatively dry woodland mire with water table fluctuating around the surface. It is therefore characterised by low ash yield and increased resinite, fusinite and inertodetrinite contents. Palynological data indicate that the peat-forming vegetation of the upper bench of the Main Seam was dominated by Taxodiaceae ( Glyptostrobus , Athrotaxis ) and Calamus palm accompanied by paludal species of the family Pinaceae and rich undergrowth of ferns and Vaccinium -type Ericaceae . Progradation of delta mouth bars to the proximity of the study section is documented by increasing proportion of allochthonous elements produced by plants colonizing the flood plain and delta plain areas ( Nyssa – Taxodium , Parrotia – Ulmus pyramidalis and Comptonia – Pinus oviformis associations). In contrast, during periods of temporary lacustrine transgressions the mire was replaced by open water environment, which favoured deposition of clay-rich coals or partings (> 30% of ash yield) of the flooding horizons in spite of fact that delta body retreated to the basin margin and the clastics were introduced from a larger distance. Rare palynomorphs indicate only sparse vegetation cover of aquatic plants during this time. Clay content seems to be the best indicator of the water level fluctuations. Facies indices (e.g. TPI and GI) show only poor correlation to hydrological and floristic changes detected in the mire–lake system.

Ethene complexes of titanocenes [Ti(II)(η2-C2H4)(Cp′)2] for Cp′ = η5-C5Me5 (1), η5-C5Me4t-Bu (2), η5-C5Me4SiMe3 (3), and η5-C5HMe4 (4) were prepared by reduction of corresponding titanocene dichlorides with magnesium in THF in the presence of ethene. Thermolysis of 1–3 in toluene solution at a maximum of 100 °C resulted in elimination of ethane, affording cleanly doubly tucked-in titanocene compounds 5–7, respectively. Experiments with 2 and 3 in NMR tubes proved that symmetrical isomers 6a and 7a were formed first, and these thermally isomerized to thermodynamically more stable asymmetrical isomers 6b and 7b. The energy difference between 7a and 7b calculated by DFT methods was 15.3 kJ/mol. Thermolysis of 4 in m-xylene required a temperature of 135 °C, affording a mixture of 8b > 8a and “dimeric dehydro-titanocene” 9 as a concurrent product of hydrogen abstraction. In contrast to thermolysis in solvents, heating of 1 and 2 in high vacuum to 135 °C resulted in sublimation of known titanocenes [Ti(C5Me5)2]...

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 [TiMe2{η5-C5Me4(CH2CH2CH═CH2)}2] (1) in toluene at 120 °C for 4 h resulted in the formation of the cyclopentadiene ring-tethered titanacyclobutane [TiIV{η5-C5Me4CH2CH2CH(κ-CH)}2CH2] (2) in virtually quantitative yields. Thermolysis in an NMR tube at 100 °C revealed that initial elimination of methane is followed by addition of one 3-butenyl double bond to a titanocene−methylidene moiety. The formed titanacyclobutane intermediate [Ti{η5-C5Me4(CH2CH2CH═CH2)}{η5-C5Me4CH2CH2CH(κ-CH)CH2CH2(κ-CH2)}] (4) then underwent a metathesis reaction with the pendant 3-butenyl to give 2 and free ethene. Cleavage of Ti−C bonds of 2 with HCl afforded stable ansa-[TiCl2{η5-C5Me4(CH2)7η5-C5Me4}] (3). Sunlight photolysis of 1 gave rise to the cyclopentadiene ring-tethered titanacyclopentane [TiIV{η5-C5Me4(CH2CH2CH(κ-CH)CH2}2] (5), the known product of cycloaddition reactions following the removal of chlorine atoms from [TiCl2{η5-C5Me4(CH2CH2CH═CH2)}2] with magnesium (as found by Horacek, M.Chem. Eur. J. 2000, 6,...

Emplacement mode and original shape and dimensions of a well exposed phonolite body in the Ceske středohoři Mountains (Czech Republic) were reconstructed using combined techniques of structural analysis of magmatic fabrics and columnar jointing together with analogue and thermal mathematical modeling of cooling for different shapes of experimental bodies. Phreatomagmatic rocks in the vicinity of some phonolite stocks in the area of interest suggest that the phonolite bodies were likely emplaced into maar-diatremes. Our modeling revealed that intrusion of magma into phreatomagmatic maar-diatreme craters can result in cryptodomes, extrusive domes, lava lakes or branched intrusions. The fabric and columnar jointing pattern of the selected phonolite body reveals best fit with an asymmetric extrusive dome emplaced into the maar crater. The scaling analysis and thermal modeling also suggest that the phonolite extrusion could have formed within 6–66 days and cooled to the background temperature after 10,000 years. Combined analogue and thermal modeling also revealed that the phonolite extrusions into maar-diatreme craters are marked by upper tier (collonade) of vertical columns and lower tier of curved and outward flaring columns. Both tiers in the phonolite extrusions are divided by a subhorizontal suture.

Hydrogen sulfide reacts with tucked-in titanocene complexes [Ti(III){η5:η1-C5Me4(CH2)}Cp*] (Cp* = η5-C5Me5) (2) and [Ti{η4:η3-C5Me3(CH2)2}Cp*] (3) and their precursors [Cp*2TiMe] (2a) and [Cp*2Ti(η2-Me3SiC≡CSiMe3)] (3a), respectively, to give the corresponding titanocene hydrosulfides [Cp*2Ti(SH)] (4) and [Cp*2Ti(SH)2] (1), respectively. Hydrogen sulfide also cleaves intramolecular σ- or π-Ti−C bonds in ansa-[TiIII(η1:η5:η5-C5Me4SiMe2CHCH2SiMe2C5Me4)] (5) and ansa-[TiII(η2:η5:η5-C5Me4SiMe2CH═CHSiMe2C5Me4)] (6), affording hydrosulfides ansa-[(η5-CH2Me2SiC5Me4)2Ti(SH)] (7) and ansa-[(η5-CH2Me2SiC5Me4)2Ti(SH)2] (8). The S−H bonds of hydrosulfides 4 and 7 were able to react with the Ti−C bonds in 2 and 5, affording titanocene sulfides [(Cp*2TiIII)2S] (11) and ansa-[{(η5-CH2Me2SiC5Me4)2TiIII}2S] (12), respectively. Combination of 7 with 2a gave rise to the mixed titanocene sulfide [ansa-{(η5-CH2SiMe2C5Me4)2Ti}S(TiCp*2)] (13). The titanium(III) d1 electrons in 11−13 form an electronic triplet state well observa...

Complex [Zr{η5-C5Me4(SiMe2H)}2Cl2] (1) was prepared by the reaction of lithium salt of 2,3,4,5-tetramethyl-1-(dimethylsilyl)cyclopenta-2,4-diene with [ZrCl4] in boiling THF. The reduction of 1 with excess magnesium in THF in the presence of excess bis(trimethylsilyl)acetylene (btmsa) afforded the bivalent metal ansa-disilylene complex with π-coordinated btmsa [Zr(η2-btmsa){η5-C5Me4(SiMe2)}2] (2). The dehydrocoupling of SiMe2H groups was accompanied by a hydrogen transfer to releasing btmsa to give a mixture of cis- and trans-1,2-bis(trimethylsilyl)ethene. Chlorination of 2 with PbCl2 afforded ansa-[Zr{η5-C5Me4(SiMe2)}2Cl2] (3) and liberated btmsa. The crystal structures of complexes, 1, 2 and 3 have been determined by X-ray crystallography.

The singly tucked-in titanocene [Ti(η5-C5Me5)(η5:η1-C5Me4CH2)] (1) reacts smoothly with ethylene glycol or hydroquinone to give bis(titanoceneoxide) (TiIII) complexes [CH2OTi(η5-C5Me5)2]2 (2) and [(η5-C5Me5)2TiOC6H4OTi(η5-C5Me5)2] (3) containing dimethylene and 1,4-phenylene link, respectively. EPR spectra of 2 in 2-methyltetrahydrofuran glass and 3 in toluene glass revealed that the unpaired d1 electrons are in interaction to form triplet state molecules. The Ti–Ti distance derived from the zero-field splittings D for the two conformations of 2 (7.42 A and 7.66 A) are in good agreement with the Ti–Ti distance of 7.2430(7) A from the X-ray diffraction single-crystal analysis. For 3, however, the Ti–Ti distance derived from D (7.65 A) is by 1.47 A shorter than the crystallographic distance of 9.1230(8) A that indicates an enhancement of the through-space dipole–dipole interaction due to the presence of a conjugated quinonide link.

The constrained geometry alkoxide [Ti(III)(η5-C5Me5){η5-C5Me4CH2CMe2O-κO}] (2) and titanocene alcoholates [Cp*2TiOR] for R = 1-adamantyl (3) and pentafluorophenyl (4) were prepared by reacting acetone and the respective alcohols with the singly tucked-in titanocene [Ti(III)(η5-C5Me5)(η5:η1-C5Me4CH2)] (1) in order to add the simplest member to constrained geometry alkoxides 5 and 6 and to extend the series of [Cp*2TiOR] (R = Me (8), tBu (7), Ph (9), and H (10)) compounds for one of the most bulky and the most electron attracting substituent. The titanocene alkoxides with the alkoxy carbon atom tethered to one of the cyclopentadienyl ligands showing the crystallographic Ti−O−C angle close to 133° are a suitable group of compounds to be compared with the [Cp*2TiOR] compounds, where the Ti−O−C angle is about 174° for 3 and 7 and 180° for 4. In spite of these Ti−O−C angle differences, the wavelength of the first electronic transition λexp(1a1 → b2), supposed to indicate the extent of the oxygen π-electron dona...

The ansa-1,2-bis(dimethylsilylene)ethane chain is exclusively activated when the parent ansa-permethyltitanocene compounds are reduced to titanium(II) either by thermolysis of titanium−methyl bonds...

The new ansa -titanocene dichloride [{(SiMePh)(η 5 -C 5 H 4 ) 2 }TiCl 2 ] ( 1 ) was prepared by one pot reaction, whereas synthesis of its methylated analogue [{(SiMePh)(η 5 -C 5 Me 4 ) 2 }TiCl 2 ] ( 3 ) was performed in two steps with isolation of corresponding silane intermediate SiMePh(HC 5 Me 4 ) 2 ( 2 ). The reaction of 1 and 3 with TiCl 4 afforded the dinuclear complexes [(SiMePh){(η 5 -C 5 R 4 )TiCl 3 } 2 ] (R = H ( 4 ) and R = Me ( 5 )). The catalysts formed from 4 and 5 after their activation with excess MAO exhibited a modest activity in ethylene polymerization. The polymer products consisted of high molar mass linear polyethylenes with a broad molar mass distribution. The presence of three paramagnetic titanium species in the mixture 4 /MAO was revealed by EPR spectroscopy. All new prepared compounds 1 – 5 were characterized by multinuclear NMR, EI-MS, IR, and solid-state structures of 1 , 3 and 5 were determined by X-ray single crystal diffraction.

Protocols for obtaining defined zirconocene complexes with polyhedral oligomeric silsesquioxanes with mono-, di-, and trisilanol functionality (SIPOSS, DIPOSS, and TRIPOSS) were established. The TRIPOSS silanolates binding one zirconocene and one chlorozirconocene moiety, [{(c-C5H9)7Si7O9O3}Zr2Cl(η5-C5H4R)4] (1, R = Bu; 2, R = H), were obtained by reacting the silanol with the respective zirconocene dichloride and triethylamine in CH2Cl2 in a 1.0:3.0:3.0 molar ratio, an excess of the zirconocene dichloride being required to suppress intramolecular dehydration of TRIPOSS. The related SIPOSS complex, [{(c-C5H9)7Si8O12O}2Zr(η5-C5H4Bu)2] (3), was prepared similarly at the stoichiometric ratio of [ZrCl2(η5-C5H4Bu)2]/ SIPOSS/NEt3 equal to 1.0:2.0:2.0. When employed in the 1.0:1.0:1.0 ratio, the same reagents afforded only the impure complex [{(c-C5H9)7Si8O12O}ZrCl(η5-C5H4Bu)2] (4), contaminated with 3 and unreacted [ZrCl2(η5-C5H4Bu)2]. Finally, the zirconocene complexes with SIPOSS and DIPOSS moiety, [{(c-C5H9)7Si8O12O}2Zr(η5-C5H5)2] (5) and [(c-C5H9)7Si7O9(OSiMe3)O2}- Zr(η5-C5H5)2] (6), respectively, were obtained by reacting [ZrMe2(η5-C5H5)2] with stoichiometric amounts of the appropriate silanols. All complexes were characterized by 1H, 13C, 29Si NMR and IR spectra, and by elemental analysis from XPS spectra. Preliminary ethene polymerization experiments showed that compounds 5 or 6 when combined with an excess of methylaluminoxane were nearly as active as [ZrCl2(η5-C5H5)2] whereas compound 2 was by about one order of magnitude less active.

Reaction of [(η5-C5Me5)TiMe3] with [(c-C5H9)7Si8O12(OH)] (SIPOSS) or [(c-C5H9)7Si7O9(OSiMe3)(OH)2)] (DIPOSS′) affords stoichiometrically the half-sandwich titanium-disiloxy-methyl complexes [(η5-C5Me5){(c-C5H9)7Si8O12O}2TiMe] (1) and [(η5-C5Me5){(c-C5H9)7Si7O9(OSiMe3)O2}TiMe] (2), respectively. Compound 2 consists of the two stereoisomers possessing the (η5-C5Me5) ligand and OSiMe3 group in syn- (2a) and anti-position (2b). The more abundant 2a (2a/2b ≈ 2:1) was isolated by fractional crystallization. Compounds 1 and 2a reacted rapidly with B(C6F5)3 to give zwitterionic complexes [(η5-C5Me5){(c-C5H9)7Si8O12O}2Ti](+)[(μ-Me)B(C6F5)3](−) (3) and syn-[(η5-C5Me5){(c-C5H9)7Si7O9(OSiMe3)O2}Ti](+)[(μ-Me)B(C6F5)3](−) (4a), respectively. Infrared spectra proved that 3 and 4a were thermally stable in the solid state, and the structure of 4a was determined by X-ray single-crystal analysis. In contrast, 1H, 13C, and 19F NMR spectra of 3 in toluene C7D8 revealed that it was completely dissociated into initial component...

The Oligo‐Miocene Most Basin is the largest preserved sedimentary basin within the Eger Graben, the easternmost part of the European Cenozoic Rift System (ECRIS). The basin is interpreted as a part of an incipient rift system that underwent two distinct phases of extension. The first phase, characterised by NNE–SSW‐ to N–S‐oriented horizontal extension between the end of Eocene and early Miocene, was oblique to the rift axis and caused evolution of a fault system characterised by en‐echelon‐arranged E–W (ENE–WSW) faults. These faults defined a number of small, shallow initial depocentres of very small subsidence rates that gradually merged during the growth and linkage of the normal fault segments. The youngest part of the basin fill indicates accelerated subsidence caused probably by the concentration of displacement at several major bounding faults. Major post‐depositional faulting and forced folding were related to a change in the extension vector to an orthogonal position with respect to the rift axis and overprinting of the E–W faults by an NE–SW normal fault system. The origin of the palaeostress field of the earlier, oblique, extensional phase remains controversial and can be attributed either to the effects of the Alpine lithospheric root or (perhaps more likely because of the dominant volcanism at the onset of Eger Graben formation) to doming due to thermal perturbation of the lithosphere. The later, orthogonal, extensional phase is explained by stretching along the crest of a growing regional‐scale anticlinal feature, which supports the recent hypothesis of lithospheric folding in the Alpine–Carpathian foreland.

Elimination of methane during thermolysis of title compounds results in the formation of σ-Ti–C bond to t-butyl or benzyl group. The t-butyl-containing titanocene methyl compound [Ti(III)Me(η5-C5Me4t-Bu)2] (5) eliminates methane at 110 °C to give cleanly [Ti(III)(η5:η1-C5Me4CMe2CH2)(η5-C5Me4t-Bu)] (6). The methyl derivative of analogous benzyl-containing titanocene [Ti(III)Me(η5-C5Me4CH2Ph)2] was not isolated because it eliminated methane at ambient temperature to give [Ti(III)(η5:η1-C5Me4CH2-o-C6H4)(η5-C5Me4CH2Ph)] (7) with one phenyl ring linked to titanium atom in ortho-position. The corresponding titanocene dimethyl compound [TiMe2{η5-C5Me4t-Bu)}2] (9) eliminates two methane molecules at 110 °C to give the singly tucked-in 1,1-dimethylethane-1,2-diyl-tethered titanocene [Ti{η5:η1:η1-C5Me3(CH2)(CMe2CH2)}(η5-C5Me4t-Bu)] (11). In distinction, the analogous benzyl derivative [TiMe2(η5-C5Me4CH2Ph)2] (10) eliminates at 110 °C only one methane molecule to afford [TiMe(η5:η1-C5Me4CH2-o-C6H4)(η5-C5Me4CH2Ph)] (12) containing one phenyl group attached to titanium in o-position and one methyl group persisting on the titanium atom. This compound is stable at 150 °C for at least 3 h. The crystal structures of 5, 6, 7, and 10 were determined.

A series of compounds [Cp*2Ti(III)OR′] where R′ is iPr3Si (2), Ph3Si (3), (tBuO)3Si (4), (c-C5H9)7Si8O12 (5), and tBu (6) were prepared by protolysis of the titanium−methylene bond in singly tucked...

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.

Singly tucked-in titanocene [Ti(III)(η5-C5Me5)(η5:η1-C5Me4CH2)] (1) reacted readily with di-tert-butyl ketone and 2,4,6-trimethylacetophenone to give permethyltitanocene derivatives [Ti(III)(η5-C5Me5){η5-C5Me4CH2C(t-Bu)2O-κO}] (2) and [(Ti(III)(η5-C5Me5)-{η5-C5Me4CH2CMe(C6H2Me3)O-κO}] (3) with the tetramethylcyclopentadienyl ring tethered to the titanium atom by ethoxy group disubstituted at Cα. Crystal structures of 2 and 3 showed that the Ti–O bond is only slightly inclined to the tethered cyclopentadienyl ligand, and the bulky mesityl or tert-butyl substituents did not impose an observable steric hindrance into molecules of 2 and 3. Whereas the Ti–O bond lengths in 2 and 3 do not significantly differ, a higher wavenumber of the 1a1 → b2 electronic transition for 2 (7326 cm–1) compared with that for 3 (6666 cm–1) indicates a more efficient oxygen-to-titanium π-electron back donation in 2. This is induced by two electron-donating tert-butyl groups on Cα compared with a combined effect of electron-donating methyl and electron-attracting mesityl substituents in 3.

The singly tucked-in permethyltitanocene 1 reacts with an excess of internal alkynes to give the 1:1 adducts 3a−c,f−i, arising from insertion of the alkyne triple bond into the titanium−methylene bond. Only the simplest species, 2-butyne, inserted two molecules to give the known compound 2; however, at a 1:1 stoichiometric ratio the 1:1 adduct 3j was also smoothly formed. 1,4-Disubstituted conjugated diynes with CMe3 or SiMe3 substituents reacted in the same way by only one triple bond to give 3d,e, respectively. The dimethylsilylene-bridged dialkynes Me2Si(C≡CR)2 (R = SiMe3, CMe3) afforded compounds 3k,l with both triple bonds reacting. After insertion of the first triple bond, the second one underwent a rearrangement which resulted in substituent shift and formation of a silacyclobutene ring linked to the titanium atom. Alkynes bearing the bulky substituents CMe3 and SiMe3 were unreactive. Among a number of olefins and 1,3-butadiene, only ethene reacted to give cleanly the 1:1 adduct 3m. The structures ...

The complex [TiCl2{η5-C5Me4(SiMe2H)}2] (3) was prepared by reacting the lithium salt of 2,3,4,5-tetramethyl-1-(dimethylsilyl)cyclopenta-2,4-diene (1) with [TiCl3(THF)3] followed by chlorination of the formed [TiCl{η5-C5Me4(SiMe2H)}2] (2) with PbCl2. The reduction of 3 with excess magnesium in THF in the presence of excess bis(trimethylsilyl)ethyne (btmse) afforded the bivalent metal ansa disilylene complex with π-coordinated btmse [Ti{η5-C5Me4(SiMe2)}2(η2-btmse)] (4). The dehydrocoupling of the SiMe2H groups was accompanied by hydrogen transfer to the free btmse. Analogous reduction of 3 with magnesium in the presence of ethene gave a mixture of titanocene [Ti{η5-C5Me4(SiMe2Et)}2] (5) and its ethene complex [Ti{η5-C5Me4(SiMe2Et)}2(η2-C2H4)] (6). The latter complex is however unstable in this mixture and rearranges with evolution of ethane to [Ti{η5-C5Me4(SiMe2Et)}{η5:η2-C5Me4(SiMe2CH═CH2)}] (7), which has its vinyl group attached by π-coordination to Ti(II). The chlorination of 4 by PbCl2 yields ansa-[TiC...

The Early Miocene Bilina Palaeodelta consists of fluvio-deltaic and lacustrine clastics deposited along the south-eastern margin of the extensional Most Basin, part of the Eger Graben in north Bohemia (Czech Republic). The Bilina succession shows evidence of repeated advances of an axial deltaic system across a thick accumulation of organic material and clay in the hangingwall of an active fault. Exposures up to ca 4·5 km long in the Bilina open-cast mine help bridge the gap between seismic scale and typical outcrop scale of observation and thus allow the relationships between small-scale and basin-scale stratal geometries to be evaluated. The Bilina Palaeodelta deposits include sand-dominated, fluvial channel fills and heterolithic sheets interpreted as delta plain strata, sand-dominated mouth-bar wedges and heterolithic sheets of prodeltaic deposits, passing distally into lacustrine clays. The depositional environment is interpreted as a fluvial-dominated, mixed-load, lacustrine delta with a high degree of grain-size segregation at the feeder-channel mouths. On the largest temporal and spatial scales, variable tectonic subsidence controlled the overall advance and retreat of the delta system. The medium-term transgressive-regressive history was probably driven by episodes of increased subsidence rate. However, at this temporal scale, the architecture of the deltaic sequences (deltaic lobes and correlative lacustrine deposits) was strongly affected by: (i) compaction of underlying peat and clay which drove lateral offset stacking of medium-term sequences; and (ii) growth of a fault-propagation fold close to the active Bilina Fault. At the smallest scale, the geometries of individual mouth bars and groups of mouth bars (short-term sequences) reflect the interaction among sediment loading, compaction and growth faulting that produced high-frequency relative lake-level fluctuations and created local accommodation at the delta front.

Half-sandwich pentamethylcyclopentadienyltitanium chloroisopropoxides [Ti(η5-C5Me5)-Ti(Oi-Pr)nCl3-n] (n = 1 (1) or 2 (2)) and methylisopropoxides [Ti(η5-C5Me5)Ti(Oi-Pr)nMe3-n] (n = 1 (3) or 2 (4)) were prepared and characterized by spectroscopic methods, and compound 1 by single crystal X-ray diffraction analysis. Compounds 3 and 4 were reacted with an equimolar quantity of B(C6F5)3, however, only compound 4 afforded a crystalline product of limited stability at ambient temperature. Its single crystal X-ray diffraction analysis revealed that it is the zwitterionic complex [(η5-C5Me5)Ti(Oi-Pr)2]+[(μ-Me)B(C6F5)3]- (5) and its crystal structure is very similar to the recently reported tert-butoxy complex [(η5-C5Me5)-Ti(Ot-Bu)2]+[(μ-Me)B(C6F5)3]- (6). The 1H, 13C, and 19F NMR spectra in C6D6 solution also showed the features analogous to those of 6. 1D NOESY experiments proved a close through space interaction of irradiated C5Me5 or OCHMe2 protons with the bridging Ti···Me-B group. The NMR data indicate the inner sphere ion pair structure of 5 in C6D6, like for 6. The crystal structure geometry of the C-H bonds of the Ti···Me-B group fulfils conditions for their agostic interaction with the titanium centre. Although structurally similar to 6, compound 5 is less thermally stable apparently due to a lower bulkiness of Oi-Pr group compared to that of Ot-Bu group.

Reactions of double tucked-in permethyltitanocene [Ti{η3:η4-C5Me3(CH2)2}(η5-C5Me5)] (1) with tert-butanol or propargyl alcohol in toluene proceeded sluggishly even with excess of the alcohol and at elevated temperature. The alcoholysis of 1 with tert-butanol afforded [Ti(η5-C5Me5)(Ot-Bu)3] (3) as the major product and Ti(Ot-Bu)4 as the minor one. The other product of the alcoholysis was pentamethylcyclopentadiene. The only isolated crystalline product was the very minor hydrolytic byproduct [{TiIII(η5-C5Me5)2}(μ-O){TiIV(Ot-Bu)3}] (2). The alcoholysis of 1 containing traces of LiI with HOCH2C≡CH, containing apparently more water than t-BuOH, gave an inseparable mixture of oily products from which several crystals of an unintended hydrolytic byproduct [{Ti(η5-C5Me5)(OCH2C≡CH)(μ-O)}3LiI] (4) were isolated. X-ray crystal structures of 2 and 4 were determined.