Dihydrogen bond interactions as a result of H2 cleavage at Cu, Ag and Au centres

A quantum chemical study of H-2 activation at fluorides of coinage metals, MF (M = Cu, Ag and Au), and its splitting was performed. The following reaction path was analyzed: FM center dot center dot center dot H-2 -> FH center dot center dot center dot HM -> HM center dot center dot center dot FH, where both the molecular complexes and the corresponding transition states have been characterized at the CCSD(T)/aug-cc-pVQZ//MP2/aug-cc-pVQZ level of theory. Further single-point CASSCF/CASPT2 calculations, including spin-orbit coupling effects, were also performed to analyze the role of nondynamic correlation. The scalar relativistic effects are included via aug-cc-pVQZ-PP basis sets used for the metals. The dihydrogen-bonded copper (FH center dot center dot center dot HCu) and silver (FH center dot center dot center dot HAg) complexes are observed as a result of H2 cleavage, while the corresponding FH center dot center dot center dot HAu gold complex is not found but the HAu center dot center dot center dot HF arrangement is observed, instead. The energetic and geometrical parameters of the complexes have been analyzed and both the Quantum Theory of Atoms in Molecules approach and the Natural Bond Orbitals method were additionally applied to analyze the intermolecular interactions.