Hydrogen bridging in the compounds X2H (X=Al,Si,P,S).

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Investigating the structural and electronic properties of simple hydrides is crucial for understanding chemical bonding.
• Previous studies on X2H systems have provided limited insights into their ground-state geometries and electronic characteristics.

Purpose of the Study:

• To computationally determine the ground-state structures, vibrational frequencies, and electron affinities of X2H hydrides (X=Al, Si, P, S).
• To compare theoretical predictions with experimental data, particularly for the Si2H radical.

Main Methods:

• Coupled cluster theory with single, double, and triple excitations [CCSD(T)] was employed.
• A series of correlation-consistent basis sets augmented with diffuse functions (aug-cc-pVXZ, X=D, T, Q) were utilized.
• High-level ab initio calculations were performed to ensure accuracy.

Main Results:

• Al2H and Si2H were found to possess H-bridged C2v structures in their ground states.
• P2H and S2H were determined to have nonbridged, bent Cs structures.
• The calculated adiabatic electron affinity for Si2H (2.34 eV) closely matches experimental values (2.31 ± 0.01 eV).

Conclusions:

• The study elucidates the distinct structural preferences of X2H hydrides based on the identity of the central atom X.
• Theoretical calculations provide reliable predictions for the properties of these reactive species.
• The excellent agreement for Si2H validates the computational approach for similar systems.