Organometallic .pi. complexes. XXII. Chemistry of .pi.-cyclopentadienyltetraphenylcyclobutadienecobalt and related compounds
About: This article is published in Journal of Organic Chemistry.The article was published on 1970-11-01. It has received 219 citations till now.
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TL;DR: An overview of the state of the art as regards the understanding of reactions in Hot Compressed Water (HCW) is given in this paper, where macroscopic and microscopic properties of HCW are described, followed by a summary of synthesis reactions.
Abstract: Hot compressed water (HCW, here water above 200 °C) possesses very interesting properties This series of articles gives an overview of the state of the art as regards the understanding of reactions in HCW In the first part the macroscopic and microscopic properties of HCW will be described, followed by a summary of synthesis reactions published The impact of the unique properties shall be discussed in part II, with the thermal degradation of tert-butylbenzene and the oxidation of methanol being used as examples The studies reported will show that the microscopic properties are of more importance to understanding reactions in HCW than assumed in the past
653 citations
TL;DR: In this article, the impact of the unique properties of HCW on the thermal degradation of tert-butylbenzene and the oxidation of methanol has been discussed, and the importance of microscopic properties for understanding reactions in HCW has been emphasized.
Abstract: Hot compressed water (HCW, here water above 200 °C) owns interesting properties The impact of the unique properties is discussed exemplary for the thermal degradation of tert-butylbenzene and the oxidation of methanol Both reactions have been conducted not only in HCW but also in other high-pressure media and from the comparison the impact of the special properties of HCW can be settled In addition the degradation of glycerol, a model substance for carbohydrates and biomass in HCW was studied This reaction shows a strong dependence on the properties of HCW The examples picture an increased specific impact of HCW with rising polarity of the reactants and intermediates The studies also points to higher importance of microscopic properties for understanding reactions in HCW than assumed in the past
300 citations
TL;DR: In this article, it was shown that the organo group Y remains attached to the cobalt throughout the catalytic cycle, which opened up the possibility of optimizing the catalyst by varying the controlling ligand Y.
Abstract: The cocyclization of alkynes with cyano compounds using organocobalt catalysts of the type [YCoL] has evolved into a versatile and technically useful method for synthesizing pyridine and its derivatives. An important advance came with the realization that the organo group Y remains attached to the cobalt throughout the catalytic cycle. This opened up the possibility of optimizing the catalyst by varying the controlling ligand Y.
261 citations
TL;DR: In this article, the development of metal carbonyl chemistry is discussed and the rate of exchange of carbon monoxide with several other CO2(CO)6(RC2R´) complexes in hexane is investigated.
Abstract: Publisher Summary This chapter discusses the development of metal carbonyl chemistry. Solutions of octacarbonyldicobalt in hydrocarbon solvents can be prepared by a high–pressure reaction between a cobalt compound, such as cobalt carbonate, and a mixture of carbon monoxide and hydrogen. Solutions of octacarbonyldicobalt in petroleum solvents react readily at room temperature with a large variety of alkynes to give complexes of general formula Co2(CO)6(RC2R´). Octacarbonyldicobalt decomposes readily at about 50°–60°C to give dodecacarbonyltetracobalt, and this thermal degradation reaction provides a convenient synthesis of Co4(CO)12 on a small scale. The rate of exchange of carbon monoxide with several other CO2(CO)6(RC2R´) complexes in hexane is investigated. The mercury carbonylcobalt compound Hg[Co(CO)4]2 is obtained by the treatment of the anion [Co(CO)4]– with mercury salts, such as Hg(CN)2 and by the treatment of Co2(CO)8 with Na/Hg. Hg[Co(CO)4]2 is obtained as orange air-stable crystals of m.p. 81°–82°C. The infrared spectrum of the solutions of the compound in CS2 show vco at 2028 and 1967 cm–l, and the nuclear magnetic resonance (NMR) spectrum of the CS2 solution shows the cyclopentadienyl proton resonance as a sharp singlet at δ 5.00. The unsymmetrical isomer 2,4–bis(pentafluorophenyl)–3,5–diphenylcyclopentadienone–n–cyclopentadienylcobalt is the only product isolated from the reaction of (π–C5H5)CO(CO)2 and C6H5C=CC6F5. The involvement of metalocyclopentadiene intermediates in the cyclotrimerization of alkynes has been established for some metal systems.
217 citations
TL;DR: A compound whose molecules consist of two metal sandwich stands carrying tentacles with affinity to metal surfaces and holding an axle that carries a dipolar or a nonpolar rotator that is characterized by several spectroscopic and imaging techniques is described.
Abstract: We describe the preparation of a compound whose molecules consist of two metal sandwich stands carrying tentacles with affinity to metal surfaces and holding an axle that carries a dipolar or a nonpolar rotator. The dipolar rotor exists as three pairs of enantiomers, rapidly interconverting at room temperature. When mounted on a gold surface, each molecule represents a chiral altitudinal rotor, with the rotator axle parallel to the surface. The surface-mounted rotor molecules are characterized by several spectroscopic and imaging techniques. At any one time, in about one-third of the dipolar rotors the rotator is free to turn and the direction of its dipole can be flipped by the electric field applied by an STM tip, as revealed by differential barrier height imaging. Molecular dynamics calculations suggest that electric field normal to the surface causes members of one pair of enantiomers to rotate unidirectionally.
176 citations