Characteristics of Double Bonds

Formula II shows one trans-double bond which is shared with the nickel atom. Furthermore, there are six carbon atoms which are in the state of an -hybridization. Each C atom shares one r-electron with the nickel. (The complex shows the correct molecular weight for NiCi2Hig, and there is no absorption in the infrared spectrum characteristic of double bonds.) This formulation has some relationship to structures which have been recently proposed by different authors (2, 4) for various allylic groups bonded to transition metal carbonyls. 

Relative abundances of the molecular ion and of ions characteristic of the picolinyl moiety, and m/z values and relative abundances of ions characteristic of double bond positions in mass spectra of picolinyl octadecenoates... 

For purely alicyclic compounds, the selection process proceeds successively until a decision is reached (a) the maximum number of substituents corresponding to the characteristic group cited earliest in Table 1.7, (b) the maximum number of double and triple bonds considered together, (c) the maximum length of the chain, and (d) the maximum number of double bonds. Additional criteria, if needed for complicated compounds, are given in the lUPAC nomenclature rules. 

Transition-metal complexes of the thionylimide anion exhibit characteristic vibrations in the regions 1260-1120, 1090-1010 and 630-515 cm , which are assigned to Oas(NSO), Os(NSO) and <5(NSO), respectively. X-ray structural data for several M-NSO complexes reveal N-S and S-O bond lengths of ca. 1.46 0.04 A indicative of double bond character in both of these bonds. 

Fig. 6. The characteristic behavior of the propagation kinetic constant, kp, and the termination kinetic constant, k as a function of double bond conversion for a multifunctional monomer polymerization...

The picolinyl esters (32) permit the location of double bonds, since these give distinctive fragmentations that are characteristic of the double-bond positions. They are easily prepared and are not too polar for separation by gas-liquid chromatography (GLC). It has been confirmed that the picolinyl esters are the most useful, since they permit unequivocal identifications even with polyunsatured components. It was also demonstrated that derivatives of this type, prepared from natural mixtures, give satisfactory resolutions when subjected to GLC on capillary columns of fused silica coated with a nonpolar methylsilicone phase, for identification by mass spectrometry (MS). 

Many aspects of the characteristics of the double-bonded functional groups have been reviewed in an impressive series of treatises, published over a period of more than 30 years. These reviews cover mostly the physicochemical aspects of double bonds electrophilic additions to carbon-carbon double bonds1, directing and activating effects of doubly bonded groups2 etc. 

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