C<r bonds

The C-C-R bond angle changes significantly in the 0° conformation of vinyl alcohol and in vinyl amine. In all of these vinyl systems, the substituent shortens the C-H bond (on the carbon to which the substituent is attached), most dramatically in the case of the substituents NHj and OH. 

The carbonyl n face of the adamantan-2-one with an electron-withdrawing group at the 5-position is nnsynunetrized by interaction of the P o bonds antiperiplanar to the C-H bonds and to the C-R bond. The orbital phase environment of the carbonyl n orbital (7) is nnsynunetrized by the more electron-donating orbitals at the P-position, which is consistent with the observed syn preference. 

The reaction of tetraethynylplatinum derivatives with mercury dihalide in acetone affords complexes 156 and 157 in which the mercury centers are coordinated to two neighboring mercury alkynyl functionalities.194 195 In turn, each alkynyl functionality interacts with the mercury center in an 7]Z-fashion. For complexes 156 and 157, the resulting Hg-Cjp bonds, which range from 2.41 to 2.77 A, are longer than typical Hg-C cr-bonds but shorter that those observed in 154. In 156, the greater flexibility of the structure allows for the formation of shorter Hg-C(.r/>) bonds than in 157 (av. Hg-C(.r/>) = 2.52 A for 156 and 2.64A for 157). The formation of such complexes is not limited to the case of... 

In bridgehead-substituted bicyclo[2.2.2]octanes 113 (R = H, Ph) the LEF treatment failed to rationalize observed 8-SCS(X) values (189,248). Since the X-C and C -R bonds are collinear, one expects upheld shifts, with absolute values decreasing in the order F > Cl > Br > I. The opposite, however, is found experimentally, so it was concluded that magnetic-field effects are probably responsible for these 8-effects (189). 

FIGURE 7. Histograms showing distributions of calculated gas phase H—C—R and R —C—R" bond angles in the aldoximes and ketoximes in Table 2. Horizontal axes are the same in both cases... 

Reversible C—C bond Formation by Dimerization of Metal Vinyiidene Complexes... 

The simplest arithmetic approach subtracts the C—C bond energy of ethane (368 kj/mol 88 kcal/mol) from the C=C bond energy of ethylene (605 kj/mol 144.5 kcal/mol). This gives a value of 237 kj/mol (56.5 kcal/mol) for the it bond energy. 

There is danger of error only when such elements are used exclusively.) The atomic orbital basis consists of a p function on each of the four carbon atoms Figure 11.15 illustrates these orbitals and the derived symmetry correct orbitals. As a result of the reflection plane that carries one ethylene into the other, these molecular orbitals are delocalized over both molecules. Figure 11.15 also shows the orbitals of the product we consider only the two C—C bonds formed and ignore the other two, which were present from the beginning and did not undergo any change. 

In the optimized geometry for the vinyl cations 403, 410 and 411 the ft-C—R bonds are confined to the same plane with the formally vacant 2p(C+) orbital, allowing optimum overlap of the latter with the jr-orbitals of the aromatic system as well as with the fi-C—R o-bond. 

The stereoelectronically controlled reaction of hydroxide ion with an anti imidate salt (62) must give the hemi-orthoamide conformer 60 where the nitrogen and the oxygen of the OR group have each an electron pair anti peri -planar to the C -OH bond also, the 0 —R bond and the N —R bond which were anti peri planar to the C-R bond in anti imidate salt 62 remain in the same relative orientation in intermediate 60. 

The scope of the reaction was then extended to the preparation of C,C-dicyclopropylmethylamines starting from alkynylimines, which represents the first example of a double C,C- r-bond insertion [148]. 

Bis(cyclopentadienyl)zirconium(III) complexes alkynyl-bridged complexes, 4, 749 dinitrogen complexes, 4, 747 electrochemical reduction, 4, 745 phosphido-bridged complexes, 4, 750 Bis(cyclopentadienyl)zirconium(IV) complexes electrochemical reduction, 4, 745 with M-C r/)-bonds, 4, 895 with M-C r/i2-bonds, 4, 887 with M-C r/i3-bonds, 4, 884 with M-H bonds, 4, 878 with M-N bonds, 4, 910 with M-0 bonds, 4, 917 with M-P bonds, 4, 927 with M-S bonds, 4, 930 with M-Si bonds, 4, 925 non-functionalized metallocene halides, 4, 870 ring-functionalized metallocene halides, 4, 874 Bis(cyclopentadienyl)zirconium(III) halides, in organic synthesis, 4, 754... 

Recently, density functional calculations were performed to determine the nature and stereochemistry of the olefin insertion into the Cu-B bond of (NHC)Cu boryl complexes (NHC = iV-heterocyclic carbene). The theoretical calculations confirm that the mechanism of insertion involves a nucleophilic attack of the boryl ligand on the coordinated olefin. Furthermore, the hyperconjugation of Cu-C (bond angles, which was also experimentally confirmed by the X-ray diffraction studies of these boryl-copper complexes <2007OM2824>. 

The simplest route to aldehydes and ketones using the same strategy is oxidation of an alcohol. So the analysis involves FGI back to the alcohol and then a C-C disconnection of one of the bonds next to the OH group. Lythgoe4 wanted to make a series of ketones 34 with various R groups to demonstrate a new alkyne synthesis. Disconnection of the C-R bond of the alcohol 35 meant that they could all be made from aldehyde 36 which can be made by the same strategy. 

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