Bonds equatorial

The conformational features of six membered rings are fundamental to organic chemistry so it is essential that you have a clear understanding of the directional prop erties of axial and equatorial bonds and be able to represent them accurately Figure 3 17 offers some guidance on the drawing of chair cyclohexane rings... 

Place the equatorial bonds so as to approximate a tetrahedral arrangement of the bonds to each carbon The equatorial bond of each carbon should be parallel to the ring bonds of its two nearest neighbor carbons... 

Following this pattern gives the complete set of equatorial bonds... 

Equatorial bond (Section 3 8) A bond to a carbon in the chair conformation of cyclohexane oriented approximately along the equator of the molecule... 

The known uranium(VI) carbonate soHds have empirical formulas, 1102(003), M2U02(C03)2, and M4U02(C03)3. The soHd of composition 1102(003) is a well-known mineral, mtherfordine, and its stmcture has been determined from crystals of both the natural mineral and synthetic samples. Rutherfordine is a layered soHd in which the local coordination environment of the uranyl ion consists of a hexagonal bipyramidal arrangement of oxygen atoms with the uranyl units perpendicular to the orthorhombic plane. Each uranium atom forms six equatorial bonds with the oxygen atoms of four carbonate ligands, two in a bidentate manner and two in a monodentate manner. 

The deep violet color of pentaphenylbismuth and certain other pentaarylbismuth compounds has been the subject of considerable speculation. It has been shown by x-ray diffraction (173) that the bismuth atom in pentaphenylbismuth is square—pyramidal. WeU-formed crystals are dichromic, appearing violet when viewed in one plane but colorless in another plane. The nature of the chromophore has been suggested to be a charge-transfer transition by excitation of the four long equatorial bonds ... 

Place equatorial bond at C-1 so that it is parallel to the bonds between C-2 and C-3 and between C-5 and C-6. 

The axial O-An bonds are clearly very strong. They cannot be protonated and are nearly always shorter than the equatorial bonds. In the case of U02 ", for instance, it is likely that the U 0 bond order is even greater than 2, since the U-O distance is only about 180 pm in spite of the difference in the ionic radii of the metal ions (U = 73 pm. Os " = 54.5 pm), this is close to that of the 0s=0 double bond found in the isostructural, osmyl group (175 pm, see p. 1085). It is usually assumed that combinations... 

Axial and equatorial bonds can be drawn following the procedure in Figure 4.10. Look at a molecular model as you practice. 

Equatorial bonds- The six equatorial bonds, one on each carbon, come in three sets of two parallel lines. Each set is also parallel to two ring bonds. Equatorial bonds alternate between sides around the ring. 

Figure 4.10 A procedure for drawing axial and equatorial bonds in chair cyclohexane.

Equatorial bond (Section 4.6) A bond to cyclohexane that lies along the rough equator of the ring. 

To make a calculation for three double bonds we need three more orbitals. These may be the three equatorial bonds of the trigonal prism with three caps that is, with 6 = 90° and = 60°, 180°, and 300° (the three other orbitals have 9 = 43.47° and 0 = 0°, 120°, and 240°). The axis for each of the three double bonds is placed midway between an equatorial orbital and one of the other orbitals. The double-bond axes lie at 6 = 63.73°, which corresponds to 101.85° for the bond angle for doubly bonded carbonyls in the M(CO)3 group (bond number n = 2). 

Now consider a molecular stretching vibration that alternately elongates and compresses axial (parallel to z, let s say) and equatorial bonds as outlined in Fig. 7-3. Imagine an extreme vibration of this kind that eventually distorts an octahedral molecule so as to gradually remove two trans ligands (again, let this direction be... 

In 1989, Krieg et al. [79] presented the crystal structure of the smectoge-nic frans-4-(as-4-cyano-cyclohexyl)cyclohexyl frans-4-n-heptylcyclohexano-ate (CCCHC). In contrast to all other substituents which are equatorially bonded in 1,4-positions to the cyclohexyl rings, the cyano group is axially attached. The molecules adopt a fully stretched conformation. Compound CCCHC has a tilted layer structure with a herringbone arrangement of layers. 

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