Infrared Spectra of the WH<sub>4</sub>(H<sub>2</sub>)<sub>4</sub> Complex in Solid Hydrogen
Xuefeng Wang
Lester Andrews
Ivan Infante
Laura Gagliardi
10.1021/ja077322o.s003
https://acs.figshare.com/articles/journal_contribution/Infrared_Spectra_of_the_WH_sub_4_sub_H_sub_2_sub_sub_4_sub_Complex_in_Solid_Hydrogen/2957821
The codeposition of laser-ablated tungsten atoms with neat hydrogen at 4 K forms a single
major product with a broad 2500 cm<sup>-1</sup> and sharp 1860, 1830, 1782, 1008, 551, and 437 cm<sup>-1</sup> absorptions,
which are assigned to the WH<sub>4</sub>(H<sub>2</sub>)<sub>4</sub> complex on the basis of isotopic shifts and agreement with isotopic
frequencies calculated by density functional theory. This <i>D</i><sub>2</sub><i><sub>d</sub></i> structured complex was computed earlier to
form exothermically from W atoms and hydrogen molecules. Annealing the matrix allows hydrogen to
evaporate and the complex to aggregate and ultimately to decompose. Comparison of the H−H stretching
mode at 2500 cm<sup>-1</sup> and the W−H<sub>2</sub> stretching mode at 1782 cm<sup>-1</sup> with 2690 and 1570 cm<sup>-1</sup> values for the
Kubas complex W(CO)<sub>3</sub>(PR<sub>3</sub>)<sub>2</sub>(H<sub>2</sub>) suggests that the present physically stable WH<sub>4</sub>(H<sub>2</sub>)<sub>4</sub> complex has more
strongly bound dihydrogen ligands. Our CASPT2 calculations suggest a 15 kcal/mol average binding energy
per dihydrogen molecule in the WH<sub>4</sub>(H<sub>2</sub>)<sub>4</sub> complex.
2008-02-13 00:00:00
CASPT 2 calculations
WH
2500 cm
4 K forms
molecule
dihydrogen
Solid HydrogenThe codeposition
mode