A solvatochromic compound is a chemical compound that changes its color based on solvent polarity. Various molybdenum anions with the form [Mo(N~N)Cl4]- and [Mo2(N~N,N~N)Cl8]2-, were found to possess solvatochromic behavior. [Li(12-crown-4)][Mo(bpy)Cl4] was found to be soluble in solvents ranging from water to acetone with an accompanying color change from yellow to blue. Similar colors were observed for the related [PPh4][Mo(bpy)Cl4] in the same solvents. When examined by UV-vis, the absorption of [Li(12-crown-4)][Mo(bpy)Cl4] shifted ~110nm across the visible region while [PPh4][Mo(bpy)Cl4] shifted ~70nm. X-ray crystal structures of both of these species show very little difference in the structure of their octahedral Mo anion and good agreement with previously known structures. A bimetallic molybdenum compound, [Li(12-crown-4)]2[Mo2(bppz)Cl8] (bppz=2,3-bis(2-pyridyl)pyrazine), was found to display solvatochromism red-shifted in respect to its monometallic counterpart, covering over ~140nm the visible region in the same solvents. However, another bimetallic compound [Li(12-crown-4)]2[Mo2(bpm)Cl8] (bpm=2,2-bipyrimidine) was more similar to [Mo(bpy)Cl4]- and displayed a similar color range and solvatochromic shift. Molecular calculations are currently underway to better understand this interesting effect.

Investigated and calculated solvatochromic characteristics of MoCl4(diimine) anions

255th National Meeting (2018)

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