Linear electron-group

An inner atom with a steric number of 2 has linear electron group geometry. 

Figure 10.4 The single molecular shape of the linear electron-group arrangement. The key (bottom) for A, X, and E also refers to Figures 10.5, 10.6, 10.8, and 10.9.

Figure 10.3 The single molecular shape of the linear electron-group arrangement.

In the electron-dot formula of CO2, there are two electron groups (two double bonds) attached to the central atom. According to VSEPR theory, minimal repulsion occurs when two electron groups are on opposite sides of the central C atom. This gives the CO2 molecule a linear electron-group geometry and a linear shape with a bond angle of 180°. 

The sp hybridization scheme corresponds to a linear electron-group geometry and a 180° bond angle, as in BeCl2(g). 

The Be atoms in BeCl2 act as Lewis acids and accept electron pairs from the Cl atoms of the neighboring linear BeCl2 groups, forming a chain of tetrahedral BeCl4 units in the solid. 

The rate difference between (91) and (92) is very small as the Me groups do not prevent mesomeric electron-withdrawal by the linear CN group. The rate difference is much more pronounced between (89) and (90), however, as the Me groups prevent the oxygen atoms of the nitro group lying in the same plane as the nucleus, p overlap between N and the adjacent C is thus markedly reduced. 

The Lewis formula predicts 2 electron groups around the central Be atom and a linear electronic geometry. There are no lone pairs on the Cd atom, so the molecular geometry is the same as the electronic geometry linear (Section 8-5). 

The Lewis formula predicts 5 electron groups around the central I atom and a trigonal bipyramidal electronic geometry. This ionic geometry is linear. 

The Lewis formula predicts 2 electron groups around each C atom, resulting in the linear structure of C302. 

A The Lewis structure of COS has one S doubly-bonded to C and an O doubly-bonded to C. There are no lone pairs attached to C. The electron-group and molecular geometries are the same linear. S = C = 0 ... 

The krypton atom in krypton difluoride does not obey the octet rule. The presence of five pair around the krypton leads to a trigonal bipyramidal electron-group geometry. The presence of three lone pairs and two bonding pairs around the krypton makes the molecule linear. The two krypton-fluorine bonds are polar covalent. However, in a linear molecule, the bond polarities pull directly against each other and cancel. Cancelled bond polarities make the molecule nonpolar. The strongest intermolecular force in the nonpolar krypton difluoride is London force. 

Particular interest attaches to the thiocyanate complexes since the mode of coordination of this ambidentate ligand is markedly influenced by the other ligands present 15 isomerization can be brought about in a number of cases by heating the solid complex or by dissolution in an appropriate solvent. The type of coordination found in a particular complex may in general only be rationalized by a consideration of both electronic and steric factors. As an example of the latter, frans-[Pd(NCS)2(PPh3)2] contains N-bonded, linear NCS groups, but in the... 

Figure 7.3 Differences in the calculated Miilliken populations for the terminal and central atoms in the linear triatomic groups as a function of valence electron count. Aq = qc - qt.

Ambiguity may arise when more than one structure contributes. Then unshared pairs in one structure may become multiple bonds in another, so that the number of electron groups around a given atom is not the same in both structures. An example is methyl azide (19). The central nitrogen is clearly linear (two electron groups), but the nitrogen bonded to CH3 has three electron groups in... 

Rabalais, J.W., McDonald, J.M., Scherr, V., and McGlynn, S.P. (1971). Electronic spectroscopy of isoelectronic molecules. II Linear triatomic groupings containing sixteen valence electrons, Chem. Rev. 71, 73-108. 

Figure 3 Linearized electronic energy spectrum around the Fermi surface (k = k,r). The degrees of freedom in the energy shells of width dEJ2 at the extrema of the spectrum are integrated over in each step of the renormalization group.

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