183.85 amu

dimer vibrational frequency = 336.8 $cm-1$

dimer force constant = 6.14 mdyne/A

References

"Optical and Raman Spectroscopy of Mass-Selected Tungsten Dimers in Argon Matrices"

Z. Hu, Jian-Guo Dong, John R. Lombardi, and D.M. Lindsay,

J.Chem.Phys., 97, 8811 (1992).