The gold dihydride molecule, AuH2:: Calculations of structure, stability, and frequencies, and the infrared spectrum in solid hydrogen

The novel AuH2 molecule has been formed in solid hydrogen by reactions of excited gold atoms from laser ablation and irradiation after thermal evaporation. The (XB2)-B-2 ground state of the AuH2 molecule is separated by a 53 kcal/mol barrier from the Au(D-2) + H-2 decomposition products and it is 27 kcal/mol more stable than Au(D-2) + H-2. The bending modes of AuH2, AuHD, and AuD2 have been observed at 638.1, 570.6, and 457.0 cm(-1). These frequencies and the lack of infrared intensity in the stretching modes are in agreement with the results of relativistic ECP DFT, MP2, and CCD calculations. The computed bending potential energy surfaces of three electronic states of AuH2 Using CASSCF/MRSDCI methods reveal that there is a barrier for decomposition of the (XB2)-B-2 ground state to Au(S-2) + H-2.