Electride

Despite the name, the electron does not leave the sodium-ammonia complex, but it is transferred from Na to the vacant orbitals of the coordinated ammonia molecules.

[7][8] Magnesium reduced nickel(II)-bipyridyl (bipy) complex have been labeled organic electrides.

An example is [(THF)4Mg4(μ2-bipy)4]–, in which the electride is the singly occupied molecular orbital (SOMO) formed by the Mg-square cluster within the larger complex.

If not evaporated, such solutions slowly lose their colour as the electrons reduce ammonia: This conversion is catalyzed by various metals.

[18][19] The intrinsic polarization between atomic nucleus and the electron anion in these high pressure electrides can lead to unique properties, such as the splitting of the longitudinal and transverse acoustic modes (i.e., LA-TA splitting, an analogue to the LO-TO splitting in ionic compound),[20] the universal but robust gapless surface state in insulating electride that forming a de facto real space topological distribution of charge carriers,[21] and the colossal charge state of some impurities in them.