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Pinkas J, Gyepes R, Císařová I, Kubišta J, Horáček M, Mach K. Decamethyltitanocene hydride intermediates in the hydrogenation of the corresponding titanocene-(η 2-ethene) or (η 2-alkyne) complexes and the effects of bulkier auxiliary ligands. Dalton Trans 2017; 46:8229-8244. [PMID: 28617500 DOI: 10.1039/c7dt01545c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1H NMR studies of reactions of titanocene [Cp*2Ti] (Cp* = η5-C5Me5) and its derivatives [Cp*(η5:η1-C5Me4CH2)TiMe] and [Cp*2Ti(η2-CH2[double bond, length as m-dash]CH2)] 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-R1C[triple bond, length as m-dash]CR2)] (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.
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Setiady Y, Lanieri L, Ab O, Maloney E, Hong E, Qiu Q, Zhou Y, Zhao J, Themeles M, Zhang X, Pinkas J, Ruiz Soto R, Ponte J. Preclinical evaluation of M-DGN549, a folate receptor alpha-targeting antibody–drug conjugate (ADC) with a DNA-alkylating payload. Eur J Cancer 2016. [DOI: 10.1016/s0959-8049(16)33030-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Fridrichová A, Varga V, Pinkas J, Lamač M, Růžička A, Horáček M. Yttrocene Chloride and Methyl Complexes with Variously Substituted Cyclopentadienyl Ligands: Synthesis, Characterization, and Reactivity toward Ethylene. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201600390] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Varga V, Lamač M, Horáček M, Gyepes R, Pinkas J. Hydrosilane-B(C6F5)3 adducts as activators in zirconocene catalyzed ethylene polymerization. Dalton Trans 2016; 45:10146-50. [PMID: 27254815 DOI: 10.1039/c6dt01946c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrosilane-B(C6F5)3 adducts were found to activate zirconocene dihalides and generate ternary catalytic systems possessing moderate to high activity in ethylene polymerization to high density polyethylene (HDPE). The activation efficacy of the adducts increased with increasing hydride donor ability and decreased with steric crowding of the particular hydrosilane used. NMR investigation of the HSiEt3/B(C6F5)3/Cp*2ZrF2 system (Cp* = η(5)-C5Me5) revealed the formation of a stable intermediate [Cp*2ZrF(FSiEt3-κF)](+)[HB(C6F5)3](-), whereas a crucial role of the [HB(C6F5)3](-) anion as a hydride donor for generation of an active cationic zirconium hydride center was elucidated.
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Večeřa M, Varga V, Císařová I, Pinkas J, Kucharczyk P, Sedlařík V, Lamač M. Group 4 Metal Complexes of Chelating Cyclopentadienyl-ketimide Ligands. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Gyepes R, Pinkas J, Císařová I, Kubišta J, Horáček M, Mach K. Synthesis, molecular and electronic structure of a stacked half-sandwich dititanium complex incorporating a cyclic π-faced bridging ligand. RSC Adv 2016. [DOI: 10.1039/c6ra14940e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The thermally robust ground singlet state complex [bis(η5-pentamethylcyclopentadienyltitanium)-μ-(η4:η4-1,2,4,5-tetrakis(trimethylsilyl)cyclohexa-1-4-diene-3,6-diyl)] (3) arises from thermolysis of Cp*TiMe3.
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Pinkas J, Císařová I, Gyepes R, Kubišta J, Mach K, Horáček M. Substituent effects in reduction-induced synthesis of ansa-titanocenes. TRANSIT METAL CHEM 2015. [DOI: 10.1007/s11243-015-0006-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Pinkas J, Lamač M. Transformations of functional groups attached to cyclopentadienyl or related ligands in group 4 metal complexes. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2015.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Pinkas J, Gyepes R, Císařová I, Kubišta J, Horáček M, Mach K. Displacement of ethene from the decamethyltitanocene-ethene complex with internal alkynes, substituent-dependent alkyne-to-allene rearrangement, and the electronic transition relevant to the back-bonding interaction. Dalton Trans 2015; 44:7276-91. [PMID: 25791134 DOI: 10.1039/c5dt00351b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The titanocene-ethene complex [Ti(II)(η(2)-C2H4)(η(5)-C5Me5)2] (1) with simple internal alkynes R(1)C≡CR(2) gives complexes [Ti(II)(η(2)-R(1)C≡CR(2))(η(5)-C5Me5)2] {R(1), R(2): Ph, Ph (3), Ph, Me (4), Me, SiMe3 (5), Ph, SiMe3 (6), t-Bu, SiMe3 (7), and SiMe3, SiMe3 (8). In contrast, alkynes with R(1) = Me and R(2) = t-Bu or i-Pr afford allene complexes [Ti(II)(η(2)-CH2=C=CHR(2))(η(5)-C5Me5)2] (11) and (12), whereas for R(2) = Et a mixture of alkyne complex (13A) and minor allene (13) is obtained. Crystal structures of 4, 6, 7 and 11 have been determined; the latter structure proved the back-bonding interaction of the allene terminal double bond. Only the synthesis of 8 from 1 was inefficient because the equilibrium constant for the reaction [1] + [Me3SiC≡CSiMe3] ⇌ [8] + [C2H4] approached 1. Compound 9 (R(1), R(2): Me), not obtainable from 1, together with compounds 3–6 and 10 (R(1), R(2): Et) were also prepared by alkyne exchange with 8, however this reaction did not take place in attempts to obtain 7. Compounds 1 and 3–9 display the longest-wavelength electronic absorption band in the range 670-940 nm due to the HOMO → LUMO transition. The assignment of the first excitation to be of predominantly a b2 → a1 transition was confirmed by DFT calculations. The calculated first excitation energies for 3–9 followed the order of hypsochromic shifts of the absorption band relative to 8 that were induced by acetylene substituents: Me > Ph ≫ SiMe3. Computational results have also affirmed the back-bonding nature in the alkyne-to-metal coordination.
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Varga V, Hodík T, Lamač M, Horáček M, Zukal A, Žilková N, Parker WO, Pinkas J. Homogeneous and heterogeneous cyclopentadienyl-arene titanium catalysts for selective ethylene trimerization to 1-hexene. J Organomet Chem 2015. [DOI: 10.1016/j.jorganchem.2014.11.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Bartošík M, Koubková L, Karban J, Červenková Šťastná L, Hodík T, Lamač M, Pinkas J, Hrstka R. Electrochemical analysis of a novel ferrocene derivative as a potential antitumor drug. Analyst 2015. [DOI: 10.1039/c5an00958h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ferrocenes represent an interesting group of drugs with potential antitumor properties.
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Havlík A, Lamač M, Pinkas J, Růžička A, Horáček M. Mixed amido-cyclopentadienyl group 4 metal complexes. RSC Adv 2015. [DOI: 10.1039/c5ra07742g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Two different kinds of nitrogen ligands and two Cp ligands with different electronic and steric effects were employed in order to demonstrate variability of the group 4 metal coordination spheres.
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Sopoušek J, Zobač O, Buršík J, Roupcová P, Vykoukal V, Brož P, Pinkas J, Vřešt'ál J. Heat-induced spinodal decomposition of Ag–Cu nanoparticles. Phys Chem Chem Phys 2015; 17:28277-85. [PMID: 25929324 DOI: 10.1039/c5cp00198f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The predicted spinodal decomposition of metastable Ag–Cu nanoparticles was experimentally induced (and detected) by heating on an high temperature X-ray diffractometer (HT XRD).
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Pinkas J, Gyepes R, Císařová I, Kubišta J, Horáček M, Mach K. Steric Effects in Reactions of Decamethyltitanocene Hydride with Internal Alkynes, Conjugated Diynes, and Conjugated Dienes. Organometallics 2014. [DOI: 10.1021/om500296h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hodík T, Lamač M, Červenková Št’astná L, Karban J, Koubková L, Hrstka R, Císařová I, Pinkas J. Titanocene Dihalides and Ferrocenes Bearing a Pendant α-d-Xylofuranos-5-yl or α-d-Ribofuranos-5-yl Moiety. Synthesis, Characterization, and Cytotoxic Activity. Organometallics 2014. [DOI: 10.1021/om500200r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Horáček M, Císařová I, Gyepes R, Kubišta J, Pinkas J, Lamač M, Mach K. Synthesis, structure, and sunlight photolysis of benzyl- and tert-butyl-substituted octamethyltitanocene dihydrosulfides. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2014.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Mijatović S, Bulatović M, Mojić M, Stošić-Grujičić S, Miljković D, Maksimović-Ivanić D, Gómez-Ruiz S, Pinkas J, Horáček M, Kaluđerović GN. Study of the anticancer properties of methyl- and phenyl-substituted carbon- and silicon-bridged ansa-titanocene complexes. J Organomet Chem 2014. [DOI: 10.1016/j.jorganchem.2013.07.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pinkas J, Císařová I, Gyepes R, Kubišta J, Horáček M, Mach K. Synthesis and Structure of Titanium(III) Bis(decamethyltitanocene) Oxide. Organometallics 2013. [DOI: 10.1021/om400624y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Strašák T, Sýkora J, Lamač M, Kubišta J, Horáček M, Gyepes R, Pinkas J. Reactivity of a Titanocene Pendant Si–H Group toward Alcohols. Unexpected Formation of Siloxanes from the Reaction of Hydrosilanes and Ph3COH Catalyzed by B(C6F5)3. Organometallics 2013. [DOI: 10.1021/om400253g] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gyepes R, Císařová I, Pinkas J, Kubišta J, Horáček M, Mach K. Sunlight Photolysis of Decamethyltitanocene Dihydrosulfide Affords the Titanium Sulfide Cage Clusters (Cp*Ti)
6
S
8
and (Cp*Ti)
4
S
6. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Pinkas J, Císařová I, Kubišta J, Horáček M, Lamač M. Synthetic transformations of a pendant nitrile moiety in group 4 metallocene complexes. Dalton Trans 2013; 42:7101-10. [DOI: 10.1039/c3dt50209k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pinkas J, Císařová I, Gyepes R, Kubišta J, Horáček M, Mach K. Ethene Complexes of Bulky Titanocenes, Their Thermolysis, and Their Reactivity toward 2-Butyne. Organometallics 2012. [DOI: 10.1021/om300461k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Pinkas J, Gyepes R, Kubišta J, Horáček M, Lamač M. Group 4 metallocene complexes with pendant nitrile groups. J Organomet Chem 2011. [DOI: 10.1016/j.jorganchem.2011.02.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Pinkas J, Gyepes R, Kubišta J, Horáček M, Mach K. Ethene Elimination during Thermolysis of Bis(3-butenyltetramethylcyclopentadienyl)dimethyltitanium. Organometallics 2011. [DOI: 10.1021/om2001487] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Pinkas J, Císařová I, Horáček M, Kubišta J, Mach K. Reactions of Hydrogen Sulfide with Singly and Doubly Tucked-in Titanocenes. Organometallics 2011. [DOI: 10.1021/om1010726] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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