How Inert, Perturbing, or Interacting Are Cryogenic Matrices? A Combined Spectroscopic (Infrared, Electronic, and...

The interactions of FeBr₂, CoBr₂, NiBr₂, and ZnBr₂ with Ne, Ar, Kr, Xe, CH₄, and N₂ matrices have been investigated using IR, electronic absorption, and X-ray absorption spectroscopies as well as DFT calculations. ZnBr₂ is linear in all of the matrices. NiBr₂ is linear in all but N₂ matrices, where it is severely bent. For FeBr₂ and CoBr₂ there is a more gradual change, with evidence of nonlinearity in Xe and CH₄ matrices as well as N₂. In the N₂ matrices, the presence of ν_NN modes blue-shifted from the "free" N₂ values indicates the presence of physisorbed species, and the magnitude of the blue shift correlates with the shift in the ν₃ mode of the metal dibromide. In the case of NiCl₂ and NiBr₂, chemisorbed species are formed after photolysis, but only if deposition takes place below 10 K. There was no evidence for chemisorbed species for NiF₂ and FeBr₂, and in the case of CoBr₂ the evidence was not strong.