The structures of simple molecules

If p orbitals are used in simple molecules PX3 interbond angles not much greater than 90° are expected. A value of 93-8° is found in PH3 and angles around 100° in many pyramidal molecules (Table 19.4). It is of interest that PF3 behaves like CO in forming complexes  

The PH2 ion, the effective radius of which has been estimated as 2-12 A, occurs in KPH2 and RbPH2, both of which have distorted NaCl structures.  

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Wang P-K, Slichter C P and Sinfelt J FI 1984 NMR study of the structure of simple molecules adsorbed on metal surfaces C2FI2 on Pt Phys. Rev. Lett. S3 82-5... 

The Structures of Simple Molecules.—The foregoing considerations throw some light on the structure of very simple molecules in the normal and lower excited states, but they do not permit such a complete and accurate discussion of these questions as for more complicated molecules, because of the difficulty of taking into consideration the effect of several unshared and sometimes unpaired electrons. Often the bond energy is not great enough to destroy s-p quantization, and the interaction between a bond and unshared electrons is more important than between a bond and other shared electrons because of the absence of the effect of concentration of the eigenfunctions. 

Steps in Using the VSEPR Theory to Predict the Structure of Simple Molecules, Cations and Anions... 

Dipole moments provide two kinds of information about molecular structure. In the first place, they tell us the extent to which a bond is polarized, a matter of importance in connection with inter molecular forces. Later we will see many examples of how interactions between dipoles and interactions between dipoles and ions contribute to an understanding of biological systems. Secondly, dipole moments provide valuable clues to the structures of simple molecules. For example, the fact that the water molecule has an appreciable dipole moment shows that the molecule is not linear but bent. Conversely, the zero dipole moment of carbon dioxide, CO2, suggests that this molecule is linear. 

In the 1931 Centenary Meeting of the British Association for the Advancement of Science, one of the subjects discussed in the Chemical Section was the structure of simple molecules. Among the speakers were Lennard-Jones, Fowler, Heisenberg, Born, Debye, W. L. Bragg, and V. Henri. 

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