Double bond electronic structure

DMF, see Dimethylformamide DM SO, see Dimethyl sulfoxide DMT (dimethoxytrilyl ether), DNA synthesis and, 1114 DNA, see Deoxyribonucleic acid DNA fingerprinting, 1118-1119 reliability of, 1119 STR loci and, 1118 Dopamine, molecular model of. 930 Double bond, electronic structure of, 16... 

Other electron-poor clusters include the 44-electron Pt3(CO)3(PPh3)4 and the 42-electron species Pd3(CO)3(PPh3)3 and [Re3Cl12p. For the 44-electron system, the 18-electron rule predicts two double bonds within the M3 triangle and for the 42-electron complexes, three double bonds. The structures of the platinum and palladium complexes are unknown, but the Re-Re distances of 2.47-2.49 A in the anion [Re l ]3- are regarded (20) as short and consistent with a formal bond order of two. 

Notice that each carbon achieves 8 electrons by this sharing. Because each shared pair constitutes a single covalent bond, the 2 shared pairs are called a double bond. The structure on the right side of Figure 5-8 shows this double bond of 4 shared electrons. 

Complexes of Olefines and. Silver Ion.—Much work has been done on the interaction of the silver ion, Ag+, with unsaturated and aromatic hydrocarbons. (Mercuric ion and some other metal ions also react with carbon-carbon double bonde.) The structure proposed by Win-gtein and Lucas11 is probably essentially correct. Let us consider a silver ion and ethylene. The system is an electron-deficient one there are 12 valence electrons and 13 valence orbitals (including one orbital for the silver ion). We may write three structures for the complex ... 

In determining the structure of C032-, it is necessary to arrange 24 electrons (four from C and six from each O, and two from the -2 charge). Complete octets for four atoms would require 32 electrons so eight electrons must be shared. Four bonds are expected, which in this case means there must be two single bonds and one double bond. The structure consistent with this distribution of electrons is... 

Recent calculations did further reveal that also the length of a finite nanotube has essential influence on its structure, which may adopt one out of three basic variants The Kekule-structure, the incomplete, and the complete Clar-structure (Figure 3.8). The first does not contain isolated double bonds, but is rather completely conjugated. The Clar-structures both feature p-phenylene moieties which, in the case of the incomplete Clar-structure, are flanked by isolated double bonds. This structural variety causes differences in electronic properties and thus in the... 

However a similar effect should then be observed in CI-CH2-CN, since the CN group is also strongly electron-attracting. Instead, the C-Cl bonds in Cl-CH3 and CI-CH2-CN are of essentially the same length [46]. Furthermore, the C-Cl bond was found to be weaker in CI-CH2-NO2 than in CI-CH3, by about 7 kcal/mol, which is not consistent with its having acquired some double bond character (structure 5). 

Although benzene contains three carbon-carbon double bonds, it has a unique arrangement of its electrons (the extra pairs of electrons are part of the overall ring structure rather than being attached to a particular pair of carbon atoms) which allow benzene to be relatively unreactive. Benzene is, however, known to be a cancer-inducing compound. 

Ethene can add on to certain metal salts it is believed that the extra electrons of the double bond can be donated to some extent an example is the compound PtCl2-C2H4 formed with platinum(II) chloride which has the structure... 

It seems now established by NMR spectroscopic investigations that a change can take place in electronic structures and atomic configuration of the dyes depending on the polarity of the solvent. Parameters describing the transition from one single bond to more double bond character vary according to the nature of the solvent (107). 

---