Structures,DNA binding,DNA cleavage,and antitumor investigations of a series of molybdenum(VI) complexes with some N(4) methyl and ethyl thiosemicarbazone ligands

Four dioxomolybdenum(VI) complexes were synthesized by reaction of [MoO₂(acac)₂] with thiosemicarbazones derived from 5-allyl-2-hydroxy-3-methoxybenzaldehyde (1), 2-hydroxynaphthaldehyde (2), 2,3-dihydroxybenzaldehyde (3), or 5-tert-butyl-2-hydroxybenzaldehyde (4). The ligands were coordinated to molybdenum as tridentate ONS donors. X-ray crystallography showed that the distorted octahedral coordination of molybdenum is completed by methanol (D) in 1a, 3a, and 4a or H₂O in 2a. The molecular structures of 1, 3, and 4, and the complexes were determined by single-crystal X-ray crystallography. Binding of the ligand and complexes with calf thymus DNA were investigated by UV, fluorescence titrations, and viscosity measurements. Gel electrophoresis revealed that all the complexes can cleave pBR322 plasmid DNA. The cytotoxic properties of the complexes against human colorectal (HCT 116) cell line showed strong antiproliferative activities in relative order 4a?>?3a?>?1a?>?2a with IC₅₀ values of 1.6, 4.0, 4.8, and 6.7?μM, respectively. The complexes exhibited more activity than the standard reference drug, 5-fluorouracil (IC₅₀ 7.3?μM). These studies show that dioxomolybdenum(VI) complexes have potential use in chemotherapy.     

Halocarbons in Antarctic Surface Waters

Abstract

Surface water samples taken during the 1988–89, 1989–90 and 1990–91 Italian expeditions were analyzed for the presence of carbon tetrachloride, trichloroethylene and tetrachloroethylene. The sample analysis was carried out by solvent extraction and capillary GC-ECD-MS determination. The above-mentioned halocarbons were at ng/l level in all water samples investigated.     

Mono and Bimetallic Complexes of Molybdenum(ii) and Tungsten(ii) Containing 4,4′-Diphenylenecarbonitrile

The complexes [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react in CH₂Cl₂ at room temperature with two equivalents of 4,4'-diphenylenecarbonitrile (dpc) to afford the new seven-coordinate complexes, [MI₂(CO)₃(4,4'-dpc-N)₂] (1 and 2) in good yield. Equimolar quantities of [MI₂(CO)₃(NCMe)₂] and PPh₃ give [MI₂(CO)₃(NCMe)(PPh₃)], which react in situ with 4,4'-dpc to yield the mono-4,4'-diphenylenecarbonitrile complexes, [MI₂(CO)₃(4,4'-dpc-N)(PPh₃)] (3 and 4). Treatment of the bis(alkyne) complexes, [WI₂(CO)(NCMe)(η ²-RC₂R)₂] (R=Me and Ph) with one equivalent of 4,4'-dpc in CH₂Cl₂ at room temperature affords the acetonitrile displaced products, [WI₂(CO)(4,4'-dpc-N)(η ²-RC₂R)₂] (5 and 6). Reaction of equimolar quantities of [WI₂(CO)(NCMe)(η ²-PhC₂Ph)₂] and 2 in CH₂Cl₂ at room temperature gives the 4,4'-dpc-bridged complex, [WI₂(CO){WI₂(CO)₃(4,4'-dpc-N)(4,4'-dpc- N,N')}(η ²-PhC₂Ph)₂] (7) in good yield. Similarly, equimolar amounts of [WI₂(CO)(NCMe)(η ²-RC₂R)₂] (R=Me and Ph) and (4) react in CH₂Cl₂ to afford the bimetallic complexes, [WI₂(CO){WI₂(CO)(4,4'-dpc-N,N')(PPh₃)}(η ²-RC₂R)₂] (8 and 9). The new bimetallic 4,4'-dpc-bridged alkyne complexes, [WI₂(CO){WI₂(CO)(4,4'-dpc-N,N')(η ²-MeC₂Me)₂}(η ²-MeC₂Me)₂] [(10), [WI₂(CO){WI₂(CO)(4,4'-dpc-N,N')(η ²-PhC₂Ph)₂}(η ²-PhC₂Ph)₂] (11) and [WI₂(CO){WI₂(CO)(4,4'-dpc-N,N')(η ²-MeC₂Me)₂}(η ²-PhC₂Ph)₂] (12) are also described.     

Selective C-alkylation Between Alcohols Catalyzed by N-Heterocyclic Carbene Molybdenum

The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H₂O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step.     

Early/Late Heteronuclear Complexes Bridged by Bifunctional Phosphorus-Based Ligands

Substituted bifunctional phosphorus-based ligands HX(CRR') n PR"H (or -PR" 2 ) [where X = O, S, NR', (substituted) cyclopentadienyl; n = 1, 2, 3; R, R', R" = alkyl, aryl, H] were employed as bridging ligands in the synthesis of early/late bridged transition metal complexes. Synthetic routes to the bifunctional ligands were also developed. First, mononuclear complexes, such as [TpZr(OCH 2 PPh 2 ) 3 ] (Tp = trispyrazolylborato), [Cp 2 Zr(1-O-2-PHR-C 6 H 10 )(Me)] (R = 2,4,6-Pr i 3 C 6 H 2 (Tipp)), [Cp 2 Zr(SCH 2 CH 2 PHR) 2 ] (R = Ph, Mes, Tipp), and phosphinoferrocene derivatives, were prepared. These complexes are suitable precursors for the introduction of a second metal (as in, for example, [TpZr( w -OCH 2 PPh 2 ) 3 Mo(CO) 3 ]).     

Synthesis of Acylated Steroidal Olefins and Their Derivatives

Acylation of cholest-5-ene and cholest-5-ene 3-one with anhydrides in the presence of zinc chloride and characterization of products thus obtained on the basis of elemental analysis, spectral data, and chemical transformations are reported.     

Book Reviews

Glossary On Air Pollution, Who Regional Publications European Series No. 9 (Director, Promotion of Environmental Health, WHO Regional Office for Europe, Scherfigsvej 8, DK-2100 Copenhagen θ) 1980, 114 pages (including an introduction, a list of reviewers and a list of the sources of definitions), stiff paper cover, format 239 ± 159 mm, ISBN 92-9020-109-6, WHO Health and Biomedical Information Programme, CH-1211 Geneva 27, SFr. 12.

Spektroskopische Methoden in Der Organischen Chemie (in German), by Manfred Hesse, Herbert Meier and Bernd Zeeh, 478 pages, including 169 figures and 86 tables, flexible paper cover, ISBN 3-13-576101-0, Georg Thieme Verlag, Stuttgart 1979, price DM 26.80.

Analysis of Polycyclic Aromatic Hydrocarbons in Environmental Samples, World Health Organisation/International Agency for Research on Cancer, IARC Publication No. 29 (Series: Environmental Carcinogens, Selected Methods of Analysis, Volume 3, edited by H. Egan, Laboratory of the Government Chemist, London, U.K. et al.) 1980, 240 pages (including 17 figures, 18 tables, many formulae, an annex with 8 methods of analysis and 29 pages of valuable references in two sections), linen, format 242 ± 186 mm, ISBN 92-8-321129-4, WHO Health and Biomedical Information Programme, CH-1211 Geneva 27, US$30 or SFr. 50.

Toxic Metals and Their Analysis by Eleanor Berman, Cook County Hospital, Chicago, Illinois, U.S.A., 304 pages (including an index of 5 pages, 29 tables and 5 figures), linen, format 241 × 163 mm, ISBN 0-85501-468-7, published 1980 by Heyden International Topics in Science, Spectrum House, Hillview Gardens, London NW4 2JQ, U.K., prices £12, US$27 or DM 56.     

钒钼协同作用下杂多酸催化阻聚甲基丙烯酸甲酯

利用一锅法制备了Dawson型钨磷酸和钼钒磷酸,并用红外光谱和X-射线衍射表征了其结构.采用沸腾法研究了合成的杂多酸对甲基丙烯酸甲酯(MMA)的催化阻聚性能,考察了杂多酸结构、杂多酸用量和反应温度等因素对MMA本体聚合反应的影响.结果表明:钒钼元素在杂多酸催化阻聚MMA的反应中具有明显的协同作用,而且,杂多酸对MMA的催化阻聚作用随钒原子数的增加而增强,杂多酸的用量和反应温度对MMA自聚反应的速率影响较大.在过氧化苯甲酰(BPO)为0.04 g,MMA为10 mL,H9P2Mo15V3O62质量为MMA的0.06%,反应温度为101.2℃或H9P2Mo15V3O62质量为MMA的0.03%,反应温度为89.4℃时,MMA自聚反应被抑制.与传统和常用酚阻聚剂相比,Dawson型钼钒磷酸具有阻聚效果好、后处理简单、无腐蚀和污染问题等优点,能够作为MMA的阻聚剂使用.     

在四氯合锌离子诱导下反式六元瓜环与碱金属离子构筑的配位超分子自组装体

在盐酸介质中,通过四氯合锌离子诱导,碱金属离子能与反式六元瓜环端口羰基氧原子直接配位构筑形成超分子自组装体。单晶结构表明在HCl介质中,四氯合锌离子形成"蜂巢结构",而且在[ZnCl₄]^2-诱导作用下,碱金属离子和反式六元瓜环端口羰基氧直接配位形成一维超分子自组装体而填充在"蜂巢结构"中。     

Pentafluorobenzoato‐dimolybdenum(II) Solvate and Co‐crystal Complexes with Benzene and Naphthalin

The quadruply bonded Mo₂⁴⁺ complex Mo₂(DAniF)₃(OOCC₆F₅) ( 1 ) [DAniF = N,N′‐bis(4‐methoxyphenyl)formamidinate] was synthesized. The solvate Mo₂(DAniF)₃(OOCC₆F₅) · (C₆H₆) ( 2 ) and co‐crystal Mo₂(DAniF)₃(OOCC₆F₅) · (C₁₀H₈) ( 3 ) complexes were obtained by self‐assembly of crystals of 1 with benzene and naphthalin, respectively. Compounds 1 , 2 , and 3 were structurally characterized by single‐crystal X‐ray diffraction. In monomer 1 , the Mo–Mo bond length of 2.0874(6) Å is typical for dimolybdenum quadruple bonds. The solvate complex 2 was stabilized by weak π–π stacking interactions between the benzene molecule and the pentafluorophenyl ring (as indicated by a center‐to‐center distance of 3.838(10) Å and a center‐to‐plane distance of 3.712(4) Å between phenyl and pentafluorophenyl ring) and intermolecular C–H ··· F–C interactions (the shortest F ··· H distance is 2.560(2) Å). In complex 3 , a one‐dimensional chain was formed by C–H ··· F–C interactions between the hydrogen atoms in naphthalin and the fluorine atoms in the monomer (H ··· F distances of 2.582(2) Å). Information on the structures in solution of the three crystals was obtained by ¹H NMR spectroscopy.