Özkar, Saim
1,2-Bis(dimethylphosphino)ethane-dicarbonyl-eta-4-diene-tungsten(0) complexes (diene = 1,3-butadiene (1), E-1,3-pentadiene (2), E,E-2,4-hexadiene (3) and E-2-methyl-1,3-pentadiene (4)) were synthesized by UV irradiation of 1,2-bis(dimethylphosphino)ethane-tetracarbonyltungsten(0) and the corresponding dienes in toluene. The constitutions of these complexes were determined by IR and NMR spectroscopy (H-1, C-13, P-31). The spectral data indicate pseudo-octahedral structures for the complexes. When the dienes are assigned to the positions b and c of the coordination octahedron, the 1,2-bis(dimethylphosphino)ethane occupies a and d (e), the two carbonyls e (d) and f positions. 1 and 3 show temperature-dependent NMR signals according to hindered ligand movements with barriers of activation of 50 and 59 kJ mol-1. In contrast, as a consequence of very different isomer populations, no ligand movement is observed for 2 and 4 up to 353 K.


Pyramidalized double bonds containing endoperoxide linkages: Photooxygenation of dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate
Saracoglu, N; Menzek, A; Sayan, S; Salzner, U; Balcı, Metin (1999-09-03)
Diels-Alder cyclo;addition utilizing singlet oxygen as the dienophile with dimethyl cis-3,8-dihydraheptalene-3,8-dicarboxylate (5) has been investigated, and monoaddition product 7 has been isolated. The addition of a second singlet oxygen to the cycloheptatriene unit in 7 gave syn-bis(norcaradiene) bis(endoperoxide) 4. H-1 NMR spectral studies and theoretical calculations indicate the increased pyramidalization in syn-4 compared with carbon analogue. The increased pyramidalization results from hyperconjuga...
Effect of substituents in sulfoxides on the enhancement of thermoelectric properties of PEDOT:PSS: experimental and modelling evidence
Zhu, Qiang; Yıldırım, Erol; Wang, Xizu; Kyaw, Aung Ko Ko; Tang, Tao; Soo, Xiang Yun Debbie; Wong, Zicong Marvin; Wu, Gang; Yang, Shuo-Wang; Xu, Jianwei (2020-06-01)
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), being the most popular conductive polymer, has been doped with various additives with the aim of improving its thermoelectric performance. Among all additives, dimethyl sulfoxide (DMSO) has been widely used for various treatments. In this work, we designed and synthesized a series of aliphatic- and aromatic-substituted sulfoxides as dopants to improve the thermoelectric properties of PEDOT:PSS. It was found that the substituents in the sul...
Insertion of Fischer Carbene Complexes into the Carbon-Carbon Bond of 1,2-Diphenylcyclopropenone: Formation of Cyclobutenones and o- and p-Methoxyphenol Derivatives
Zora, Metin (American Chemical Society (ACS), 1994-08-01)
Covalent immobilization of alpha-amylase onto poly(2-hydroxyethyl methacrylate) and poly(styrene-2-hydroxyethyl methacrylate) microspheres and the effect of Ca2+ ions on the enzyme activity
Tumturk, H; Aksoy, S; Hasırcı, Nesrin (2000-02-01)
alpha-Amylase (1,4-alpha-D-glucan-glucanohydrolase; EC, Type VI-B from porcine pancreas, extra pure 29 units mg(-1)) was covalently immobilized on poly (2-hydroxyethyl methacrylate), p(HEMA), and poly (styrene-2-hydroxyethyl methacrylate), p(St-HEMA) microspheres, which were activated by using epichlorohydrin (ECH). The properties of the immobilized enzyme were investigated and compared with those of the free enzyme. For the assays carried out at 25 degrees C and pH 6.9, the relative activities were...
A theoretical study on camptothecin-AM1 treatment
Türker, Burhan Lemi (2001-08-13)
Camptothecin (irinotecan), a new cytotoxic agent having antitumor activity and especially used in the treatment of advanced colorectal cancers is considered for AM1-RBF type semiempirical quantum chemical treatment together with some analogs of camptothecin. The structural properties and energetics of these molecules have been compared. The structures arising from monoprotonation of camptothecin at various sites are analyzed from thermodynamic point of view.
Citation Formats
S. Özkar and C. KREITER, “HINDERED LIGAND MOVEMENTS IN TRANSITION-METAL COMPLEXES DECARBONYL (ETA-4-DIENE) TUNGSTEN(0),” JOURNAL OF ORGANOMETALLIC CHEMISTRY, pp. 79–87, 1992, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/41392.