What is the essential criteria for the determination of the dipole moment in different complex compounds/molecules?Is dipole moment, is related with the stability of complexes?Please help.

Dear Anurag,

Molecular vibrational frequencies lie in the IR region of the electromagnetic spectrum and they can be measured using the IR technique. In IR, light having different frequencies is passed through a sample and the intensity of the transmitted  light is measured at each frequency.When molecules absorb IR radiation, transitions occur from a ground vibrational state to an excited vibrational state. In order for a molecule to be IR active there must be a change in dipole moment as a result of the vibration that occurs when IR radiation is absorbed. Dipole moment in a heteronuclear diatomic molecule can be described as uneven distribution of electron density between the atoms. One atom is more electronegative than the other and has a net negative charge. Dipiole moment can be expressed mathematically as 

The relationship between IR intensity and dipole moment is given as

relating this to intensity of the IR radiation, we have have the following equation below.

where  is the dipole moment and Q is the vibrational coordinate. The transition moment integral for IR can also be written as 

the transition moment integral gives information about the probability of a transition occuring. i and f represent are initial and final states. is the wave function. Relating this to IR intensity we have

where is the dipole moment  and has the cartesian coordinates, ,, . In order for a transition to occur by dipole selection rules , at least one of the integrals must be non zero

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But sir, my exact question was simply how to compare between the dipole moment of different given complex compounds as asked in exams i.e which compound has relatively higher dipole moment as compared to some other.