- The synthesis of quaternary ammonium salts from ammonium salts and dialkyl carbonate
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Quaternary ammonium salts were synthesized from ammonium salts and dialkyl carbonates over an ionic liquid catalyst 1-ethyl-3-methylimidazolium bromide. The Royal Society of Chemistry 2006.
- Zheng, Zhuoqun,Wu, Tinghua,Zhou, Xiaoping
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p. 1864 - 1865
(2008/03/14)
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- Process for preparing tetrafluoroborate salt and intermediates thereof
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There is provided a process for preparing tetraalkyl ammonium halide utilizing a catalytic amount of acetonitrile in a reaction under pressure and at an elevated temperature of an alkyl halide and a trialkyl halide and in which tetrafluoroborate can be subsequently prepared.
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- An azophenol-based chromogenic anion sensor
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(equation presented) A new chromogenic azophenol-thiourea based anion sensor, 2, has been developed. This system allows for the selective colorimetric detection of F-, H2PO4-, and AcO-. Selectivity trends turned out to be dependent upon guest basicity and conformational complementarity between 2 and the guest.
- Lee, Dong Hoon,Lee, Kwan Hee,Hong, Jong-In
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- Intermediates useful in a synthesis of 2-chloro-2'-deoxyadenosine
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This invention relates to a novel process for preparing 2-chloro-2'-deoxyadenosine (2-CdA) having the following formula STR1 from a compound of the following formula STR2 The invention also relates to intermediates which are useful in preparing 2-CdA. The compound 2-CdA is useful as an antileukemic agent, i.e., in treating leukemias, such as hairy cell leukemia.
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- Synthesis, structure, and characterization of the tetranuclear iron(III) oxo complex [Fe4O2(BICOH)2(BICO)2(O 2CPh)4]Cl2
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The synthesis and characterization of a novel molecule containing the bis(μ3-oxo)tetrairon(III) core, [Fe4O2(BICOH)2-(BICO)2(O 2CPh)4]Cl2, where BICOH is bis(N-methylimidazol-2-yl)carbinol, are reported. Structural, magnetic, and Mo?ssbauer studies indicate the presence of antiferromagnetically coupled iron(III) ions with a diamagnetic ground state. The {Fe4O2}8+ core is formally comprised of two (μ-oxo)bis(μ-benzoato)diiron(III) centers, of the kind present in the marine invertebrate respiratory protein hemerythrin, joined by linkages between oxo ligands and iron atoms of the {Fe2O}4+ constituents. Additional bridges between the two {Fe2O}4+ components are provided by the BICO- ligands. The resulting tetranuclear complex has a planar Fe2O2 kernel with Fe-O bond lengths of 1.94 (1) and 1.98 (1) A?, Fe-O-Fe angles of 95.7 (5)°, and O-Fe-O angles of 84.3 (5)°. Within the {Fe2O(O2CPh)2}2+ subfragment the Fe-O bond lengths are 1.884 (9) A? and, shared with the kernel, 1.94 (1) A?, while the Fe-O-Fe angle is 119.0 (6)°. Similar {Fe4O2} tetranuclear cores occur in the minerals amarantite and leucophosphite, as well as the recently reported discrete complex [Fe4O2(O2CCF3)8(H 2O)6], the geometric properties of which are compared and analyzed. Optical spectroscopic features at ～465-475 and 565-575 nm are suggested to be characteristic of the {Fe4O2}8+ unit. The coordinating properties of the biologically relevant bidentate BICOH ligand and its deprotonated, tridentate bridging BICO- derivative are described. X-ray studies were carried out on [Fe4O2(BICOH)2(BICO)2(O 2CPh)4]Cl2·5H 2O·2CH3CN, which crystallizes in the trigonal system, space group R3, with a = b = 39.128 (8) A?, c = 17.833 (7) A?, V = 23 644 A?3, Z = 9, and ρcalcd = 1.106 g cm-3.
- Gorun, Sergiu M.,Lippard, Stephen J.
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p. 149 - 156
(2008/10/08)
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- Chromium tricarbonyl facilitated nucleophilic aromatic substitution by metal carbonyl anions: The synthesis and molecular structure of a new class of bimetallic π-arene complexes
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The highly nucleophilic metal carbonyl anions [CpFe(CO)2]- and [(C5Me5)Fe(CO)2]- (C5Me5 ≡ Cp*) react with (η-XRC6H4)Cr(CO)3 substrates in a previously unknown type of nucleophilic aromatic substitution to form (η6-{CpFe(CO)2}RC6H4)Cr(CO) 3 products. A variety of less reactive metal nucleophiles, including [CpMo(CO)3]-, [CpNi(CO)]-, [Mn(CO)5]-, and [Co(CO)4]-, fail to participate in the substitution reactions. The structure of (η-{CpFe(CO)2}ClC6H4)Cr(CO)3 has been determined by X-ray crystallography. The compound crystallizes in the space group P21/n with four molecules in the unit cell of dimensions a = 7.969 (2) A?, b = 18.982 (4) A?, c = 10.789 (2) A?, and β = 91.45 (3). Full-matrix least-squares refinement yielded R = 0.0353 for 2153 reflections. The structure shows that the conformation of the Cr(CO)3 fragment is determined by a cogging of the carbonyl ligands of the CpFe(CO)2 and Cr(CO)3 units to avoid steric interactions, although 1H and 13C NMR studies failed to show a perceptible barrier to Cr(CO)3 rotation about the Cr-Phcentroid vector. Certain haloarene substrates react predominantly through an apparent electron-transfer pathway to produce [CpFe(CO)2]2 and (η-RC6H5)Cr(CO)3. The fraction of reduced products formed is dependent on (1) the reducing power of the anion ([Cp*Fe(CO)2]- ? [CpFe(CO)2]-), (2) the electron-donating ability of the R group (electron donor ? electron acceptor), (3) the substitution pattern of the arene (in general ortho ? meta ? para), and (4) the identity of the halogen leaving group (I ? Cl > F).
- Heppert, Joseph A.,Morgenstern, Mark A.,Scherubel, Devin M.,Takusagawa, Fusao,Shaker, Mohammad R.
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p. 1715 - 1723
(2008/10/08)
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- Carbonylation process
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The invention providess a process for carbonylating a nitrogen-containing organic compound, selected from the group consisting of nitro, nitroso, azo, and azoxy compounds, by reacting said nitrogen-containing organic compound, with carbon monoxide, wherein the improvement comprises the step of: (a) reacting said nitrogen-containing compound with carbon monoxide, in the presence of a primary amine and a catalyst, essentially free of redox active metal components selected from the group consisting of rhodium and ruthenium.
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- Structural (EXAFS) and solution equilibrium studies on the oxotechnetium(V) complexes TcOX4- and TcOX52- (X = Cl, Br)
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The equilibrium between the technetium(V) complexes TcOCl4- and TcOCl52- has been investigated in 12 M HCl and in CH2Cl2 solutions by Raman spectroscopy. In both media the five-coordinate complex is the predominant species, but in the aqueous medium water competes for the sixth coordination site and causes formation of the six-coordinate TcOCl52- anion to be even less favorable (Keq = 0.6 ± 0.3 M-1 in CH2Cl2; Keq = 0.0015 ± 0.0010 M-1 in 12 M HCl). Procedures are described for generating good yields of either TcOX4- or TcOX52- (X = Cl, Br) salts from the same reaction mixture. The complexes TcOCl4-, TcOCl52-, TcOBr4-, TcOBr52-, and TcI62- have been structurally characterized by EXAFS techniques. Observed Tc=O and Tc-X bond lengths are consistent with the known dependence of bond length on coordination number, the established structural trans effect induced by the Tc=O linkage, and existing crystallographic data on TcOCl4- and related molybdenum(V) complexes.
- Thomas, Rudy W.,Heeg, Mary Jane,Elder,Deutsch, Edward
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p. 1472 - 1477
(2008/10/08)
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- Reactions of Acetylenes with Noble-metal Carbonyl Halides. Part 6. Carbonyl Insertion to give Cyclic Organo-carbene Complexes of Platinum(II): Synthesis and X-ray Structure of the Complex cis-(PPh3)Cl2>
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The complex reacts with ethyl phenylpropiolate, PhCCCO2Et, to give (CO)Cl> (1) which contains a six-membered carbenoid ring bonded to platinum.In acetonitrile, complex (1) gives cis-(CO)Cl2> (2).The interconversion of complexes (1) and (2) with KCl and respectively are reported and a mechanism for the formation of (1) is proposed.Reaction of complex (1) with PPh3 results in displacement of CO to give cis-(PPh3)Cl2> (3). 13C N.m.r. studies of complexes (2) and (3) with specific isotopic labelling are reported.The crystal structure of complex (3) has been solved by Patterson and Fourier methods from counter data and refined by block-matrix least squares to a final conventional R of 0.048 for 5842 independent observed reflections.Crystals of (3) are triclinic, space group P1, with unit-cell dimensions a = 11.523(3), b = 11.994(4), c = 14.512(6) Angstroem, α = 106.2(1), β = 88.8(1), γ = 73.7(2) deg, and Z = 2.The crystals contain discrete molecules in which the co-ordination of the platinum atom is slightly distorted square planar.Selected bond lengths (Angstroem) are Pt-P 2.244(2), Pt-C 1.933(8), Pt-Cl (trans to carbenoid carbon atom) 2.350(3), and Pt-Cl (trans to PPh3) 2.347(2).On the basis of reactivites and spectroscopic data, an unambiguous relationship has been established between compound (3) and its precursors.
- Canziani, Franco,Galimberti, Franco,Garlaschelli, Luigi,Malatesta, Maria Carlotta,Albinati, Alberto,Ganazzoli, Fabio
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p. 827 - 834
(2007/10/02)
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