Continuum in the X-Z---Y weak bonds: Z= main group elements

Area of Science:

• * Theoretical Chemistry
• * Computational Chemistry
• * Quantum Chemistry

Background:

• * Weak interactions, including hydrogen bonds, are crucial in chemistry and biology.
• * Understanding the subtle electronic effects governing these interactions is key.
• * Previous studies often categorized bond length changes without a unified framework.

Purpose of the Study:

• * To investigate the continuum of X-Z bond length variations in X-Z---Y complexes.
• * To identify the underlying electronic factors responsible for blue-shifting, zero-shifting, and red-shifting.
• * To propose a generalized model for weak interactions and chemical bonding.

Main Methods:

• * Employed ab-initio molecular orbital calculations.
• * Utilized Z=Hydrogen, Halogens, Chalcogens, and Pnicogens as model systems.
• * Analyzed the interplay between negative hyperconjugation and charge transfer.

Main Results:

• * Demonstrated a continuum in X-Z bond length changes, tunable by X and Y groups.
• * Identified competition between negative hyperconjugation and charge transfer as the primary driver.
• * Showcased how varying orbitals/electrons around Z create diverse weak interactions.

Conclusions:

• * Proposed a continuum model for X-Z bond length variation in weak interactions.
• * Explained that the anti-bonding orbital model applies across different weak interaction classes.
• * Extended the continuum concept to general chemical bonding principles.