Bond distances ethylene oxide

The stmctural parameters of ethylene oxide have been determined by microwave spectroscopy (34). Bond distances iu nm determined are as follows C—C, 0.1466 C—H, 0.1085 and C—O, 0.1431. The HCH bond angle is 116.6°, and the COC angle 61.64°. Recent ah initio studies usiug SCF, MP2, and CISD have predicted bond lengths that are very close to the experimental values (35,36). 

As shown in Table 1, a remarkable variety of alkene complexes bearing metal centers in a low oxidation state have been isolated and their structures have been determined by X-ray analysis. All the C-C bond distances in olefins coordinated to early transition metals at low oxidation states are more or less elongated compared to free ethylene. These structural data, together with those from NMR studies [14], indicate a major contribution of the metallacyclo-propane structure (2), a fact which is also supported by calculation studies [15]. In the case of ethylene bridging two metal centers such as [ Cp2ZrX 2(iu-f/-C2H4)] (3), the M-C bond could be characterized as a er-bond and there is a little contribution from the / -ethylene canonical structure [16-18]. 

C—C bond distance,17 8 conjugating power, c-381 1481 and magnetic susceptibility 8 of ethylene oxide. 

C—C bond distance,oonjn fttin power, - - nd magnetic i cepUbi)it rM of ethylene oxide. 

Unmodified ( native ), polymeric membranes often show strong plasticization effects when exposed to high partial pressures of C02, hydrocarbons, or ethylene oxide. Plasticization increases the inter-molecular distance and molecular motion of the polymer chains due to a decrease in inter- and/or intramolecular attractive forces. Consequently, the permeability for all feed components increases, whereas the selectivity decreases. Strong plasticization can even lead to a partial dissolution of the membrane. Hydrocarbons present in natural gas can reduce the selectivity by 30-50% due to plasticization. Plasticization can be limited by cross-linking the polymer chains through either covalent or ionic bonds (Figure 2) but will not be detailed here further (see Ref. 36 instead). - ... 

Poly(ethylene oxide) is the most commonly used polymer in personal, home and health care applications, due its water solubihty in combination with a very low toxicity. These attractive properties of poly(ethylene oxide) can be ascribed to the distance between the alternating oxygen atoms in the chains that is in agreement with the hydrogen distances in hquid water allowing the formation of an extensive hydrogen-bonding network with water [12, 13]. 

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