Seventeen electron configuration

The 17-electron species see Seventeen Electron Configuration) formed can undergo rapid substitution since associative pathways of low activation energy exist for them. Recombination of the substituted flagments can yield the monosubsti-tuted, disubstituted, or more fully substituted complexes. The rate-determining step would be cleavage of the metal-metal bond since all other steps are relatively fast. This pathway may be preferred for photochemical substitution. Clearly, this pathway is not open to mononuclear analogs. The reactivity of low valent metal radical complexes has been reviewed. ... 

This ion now can be reduced to one with an 18-electron configuration. When treated with a solution of potassium in liquid ammonia it forms the compounds K3Ni(CN)4 (with seventeen electrons) and eventually K4Ni(CN)4, in which the ions have apparent valencies of 1 and 0, respectively. The latter compound... 

The atom in question is an atom of chlorine. Seventeen electrons will fill with a configuration of ls22s22p63s23p5. 

Thus, sodium s eleven electrons are 2,8,1 while chlorine s seventeen electrons are 2,8,7. If sodium gives up an electron and chlorine accepts one, the former achieves the 2,8 configuration of neon and the latter the 2,8,8 configuration of argon. 

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