Carbon monoxide interactions

An interesting oxycarbonyl cluster has been isolated in the reaction of 0s04 with CO under pressure. This was an intermediate in the preparation of the Os3(CO)i2. The X-ray analysis has established this as a cubane structure, with an oxygen bridging the four faces of the osmium tetrahedron. The Os-Os distance is 3.20 A and implies no bonding between the osmium centers. This molecule is of obvious interest as a potential model in the studies of carbon monoxide interaction with metal oxides and also metal surfaces, when the formation of metal oxides occurs (200). 

The rates of production of the heat evolved when a dose of carbon monoxide interacts with NiO(250) containing either 0 (ads) ions (Reaction 4) or C(V(ads) ions (Reaction 2) are given as a function of time in Figure 6. In both cases, the same amount of carbon monoxide has been introduced previously to this particular dose. Thermochemical cycles and direct observation of the presence of carbon dioxide in the cold trap confirm that, during the interaction of this particular dose of CO, carbon dioxide is desorbed to the gas phase. 

Study of Hydrogen and Carbon Monoxide Interactions with PaUadium-Y Zeolite by ESR and IR Spectroscopy... 

We were interested in the change in the oxidation state of Pd (II), incorporated in the zeolite, during heat treatment in oxygen or in vacuo. Hydrogen and carbon monoxide interactions were also studied. The experiments involved two techniques ESR, which provides direct identification of palladium in an ionic state, and IR spectroscopy, which gives information on the superficial structure of the exchanged zeolite and on the adsorbed species. 

These transformations share common initial steps in which the carbon monoxide interacts with the trialkylborane to give an intermediate organoborate. This readily transfers one of its alkyl groups to the carbon atom derived from carbon monoxide to give intermediate X (Figure B3.1). 

Such a mechanism of carbon monoxide interaction with active centers is compatible with the data on the slow copolymerization of CO with ethylene found for the ethylene polymerization by some one-component catalysts This copolymerization may proceed also in the case of two-component catalysts resulting in an increase of the number of radioactive tags in the polymer with time (see Fig. 1). Arguments have been given that the rapid increase of polymer radioactivity in the initial period (5-10 min) is due to the insertion of the first CO molecule into the active metal-carbon bond. 

Isocyanates can be prepared from azides by reaction with carbon monoxide. The reaction has been at first reported to proceed only with catalysis of rhodium or iridium carbonyl complexes . Later work has however shown that aryl azides and carbon monoxide interact without catalysis at temperatures of 160-180° and pressures of 200-300 atm, yielding aryl isocyanates (86) in good yields. Ethyl azidoformate yielded under these conditions ethoxyisocyanate . 

Most of the gas adsorbed at room temperature ( 99%) is desorbed, either at room temperature or at higher temperatures as carbon monoxide. The possibility of an interaction between carbon monoxide and cationic or anionic sites without formation of desorbable carbon dioxide must be therefore envisaged. Infrared measurements have shown, indeed, that carbon monoxide interacts with both types of sites (60). 

The same sequence of adsorptions (O2-CO) was also studied on the surface of NiO(250°) [41). As in the case of NiO(200°), adsorption of carbon monoxide on the sample containing preadsorbed oxygen (1.90 cm /gm) (Table II) changes the color of the sample from black to green and decreases its electrical conductivity (1.8 x 10- ohm-i cm- ) to the low initial value. However, this time, carbon dioxide is found in the cold trap placed near the sample. Calorimetric results reported in Table II indicate also that carbon monoxide interacts with preadsorbed oxygen since the heats of adsorption of carbon monoxide are higher on the black sample (Table II) than on the pure surface of NiO(250°) (Fig. 12). 

While stable binary actinide carbonyls are still unknown, research in this area focused mainly on the detection and theoretical investigation of unstable molecules such as the monocarbonyl complexes of thorium and uranium. The possible molecular structures U-GO, U-OG, and GUO of carbon monoxide interacting on a uranium metal surface have been studied by density functional theory (DFT).14 GUO has been produced experimentally by reaction of laser-ablated U atoms with CO in excess argon and trapped in a triplet state in solid argon at 7 K.15 Studies of the reaction of thorium atoms with CO have been carried out. The reaction of laser-ablated thorium atoms with carbon monoxide in excess neon gave the first thorium carbonyl complex, Th-GO, which rearranges photochemically to CThO (Scheme l).16... 

Infrared spectroscopic studies have shown that adsorbed carbon monoxide interacts with Brensted acid Si(OH)Al groups of the zeolite H-ZSM-5 forming hydrogen-bonded H-CO and H—OC species, which are characterized by C-0 stretching IR absorption bands at 2175 and 2112 cm", respectively. By means of variable-temperature FTIR spectroscopy, these C-bonded and O-bonded adducts were found to be in a temperature dependent equilibrium which can be described as ZH CO = ZH- OC, where Z stands for the zeolite framework. The corresponding enthalpy change was found to be AH° = 4.2 kJ mol", as derived from a van t Hoff analysis of the intensity of the corresponding IR absorption bands as a function of temperature. 

Direct administration. With all the knowledge in the literature about how carbon monoxide interacts in biological systems, it is clear that this molecule could be exploited for use in medicine. Carbon monoxide regulates many biological functions and the introduction of CO from an external source could potentially remediate many diseases and conditions. 

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