We show that the continuum behavior in the variation of the X-H stretch from blue- to red- through zero- shifting observed in H-Bonds also holds good for X-Z stretch in X-Z---Y complexes where Z = a main group fragment. This has been studied by ab-initio electronic structure calculations using Z= Hydrogen, Halogens, Chalcogens and Pnicogens as prototypical examples. Our analysis revealed that, the competition between negative hyperconjugation within the donor (X-Z) molecule and Charge Transfer (CT) from the acceptor (Y) molecule is the primary reason for the X-Z bond length change. Proper tuning of X- and Y-group for a particular Z- can change the blue-shifting nature of X-Z bond to zero-shifting and further to red-shifting. In contrast to the weak intermolecular interactions in the main group compounds, electron-saturated (18-electron) transition metal complexes show reluctance towards weak metal-bond formation. We propose that the nature of valence electron density distribution in transition metal complexes is the primary reason for this reluctance. We propose that weak interactions form a part of the larger continuum of the nature of the chemical bond. The strong among the so-called weak interactions are stronger than the weak among regular X-Z bonds. We end with an unconventional use of halogen bond to strengthen the sextuple bond in Cr2.
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