"Characterization of the First Examples of Isolable
Molecular Hydrogen Complexes; M(CO)3(PR3)2(H2)
(M = Mo, W; R = Cy, i-Pr). Evidence for a Side-on Bonded H2 Ligand"
G. J. Kubas, R. R. Ryan, B. I. Swanson, P. J. Vergamini, H. J. Wasserman; J. Am. Chem. Soc., 106, 1984 p. 451-452