High-pressure Na-3(N-2)(4), Ca-3(N-2)(4), Sr-3(N-2)(4), and Ba(N-2)(3) featuring nitrogen dimers with noninteger charges and anion-driven metallicity

• Charged molecular species, such as [N-2](x-), [O-2](x-), [C-2](x-), and [S-2](x-), follow the paradigm of carrying integer values of electrons. Here, the Na-3(N-2)(4), Ca-3(N-2)(4), Sr-3(N-2)(4), and Ba(N-2)(3) compounds were produced and characterized <70 GPa and evidenced to be composed of paradigm-breaking [N-2](x-) dimers with noninteger charges of -0.75, -1.5, -1.5, and -0.67, respectively. The anion-driven metallicity of the compounds is proposed as the physical mechanism enabling the noninteger electron count of the [N-2](x-) dimers. The properties of these dimers and the compounds bearing them are demonstrated to depend on their noninteger charge, paving the way to materials with electron-tunable features.

Subject headings

NATURVETENSKAP  -- Kemi -- Annan kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Other Chemistry Topics (hsv//eng)

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art (subject category)