. 2021 Feb 15;12(12):4599–4622. doi: 10.1039/d0sc06028c

Promising ions for the exploratory synthesis of functional inorganic nitrides and comparison to their oxide counterparts.

Confirmed (O²⁻)^58,69–72	Confirmed (N³⁻)	To be investigated (N³⁻)^a	Relation to O²⁻
Full-fledged multiple-bond formation (>1.95 v.u.)
^[3]N⁵⁺, ^[4]Cl⁷⁺, ^[4]V⁵⁺, ^[4]Cr⁶⁺, ^[5,6]Mo⁵⁺, ^[4–6]Mo⁶⁺, ^[6]W⁶⁺, ^[4–5]Re⁷⁺, ^[4–5]Os⁸⁺, ^[6–8]U⁶⁺	^[2]C⁴⁺, ^[2]N⁵⁺, ^[2]S⁴⁺, ^[5]Mo⁶⁺, ^[4]W⁶⁺	V⁴⁺, V⁵⁺, Cr^5,6+, Nb⁵⁺, Mo⁵⁺, Tc⁷⁺, Ta⁵⁺, Re⁷⁺, Os⁸⁺, U⁶⁺	χ _N³⁻ < χ_O²⁻; multiple-bond formation facilitated for N³⁻. Triple bond impossible for O²⁻; special geometry required for N³⁻

		(>1 v.u.: Ti⁴⁺, Se^4,6+, As⁵⁺, Br^5,7+, Te^4,6+, I^5,7+, W⁵⁺, Os^6,7+, Bi⁵⁺, Np^5,6,7+)

Coupled electronic-vibrational degeneracy: the Jahn–Teller effect
^[6]Cr²⁺, ^[6]Mn³⁺, ^[6]Cu²⁺	^[3]Cr³⁺, ^[6]Co³⁺, ^[6]Cu²⁺	^[6]V³⁺, ^[6]Cr²⁺, ^[6]Mn³⁺, ^[6]Fe²⁺, ^[3]Fe³⁺, ^[6]Co²⁺, ^[6]Mo⁵⁺, ^[6]Os⁷⁺	χ _N³⁻ < χ_O²⁻; increased covalency thus distortion magnitude for N³⁻

Minor: ^[6]Co²⁺, ^[6]V³⁺ and ^[6]Mo⁵⁺, ^[6]Os⁷⁺

Coupled electronic-vibrational near-degeneracy: the pseudo Jahn–Teller effect
^[4–7]Ti⁴⁺, ^[4–6]V⁵⁺, ^[6–10,12]Y³⁺, ^[6–10]Zr⁴⁺, ^[4–8]Nb⁵⁺, ^[4–6]Mo⁶⁺, ^[6–8]Hf⁴⁺, ^[6–7]Ta⁵⁺, ^[4–6]W⁶⁺, ^[4–6]Re⁷⁺, ^[4–6]Os⁸⁺. Minor: ^[6–8]Sc³⁺, ^[5–6]V⁴⁺, ^[4]Cr⁶⁺, ^[4]Mn⁷⁺, ^[6–10,12]Y³⁺; ^[5]Cr²⁺, ^[5]Co²⁺, ^[5]Cu²⁺, ^[6]Zn²⁺, ^[6]Cd²⁺, ^[6]Hg²⁺	^[6]Y³⁺, ^[4]Mo⁶⁺, ^[8]Hf⁴⁺, ^[4]Ta⁵⁺, ^[4]W⁶⁺	Sc³⁺, Ti⁴⁺, Zr⁴⁺	χ _N³⁻ < χ_O²⁻; optimal match of atomic orbital energies shifted to cations of lower electronegativity. Increased covalency thus distortion magnitude for N³⁻

		Observed, but distortion magnitude inconclusive due to paucity of data: ^[4]V⁵⁺, ^[4]Cr⁶⁺, ^[4,6]Nb⁵⁺

Lone-pair stereoactivity
^[3]P³⁺, ^[3]S⁴⁺, ^[2,4]Cl³⁺, ^[3]Cl⁵⁺, ^[3–8]As³⁺, ^[4–10]Se⁴⁺, ^[6–8]Br⁵⁺, ^[3–9]Sn²⁺, ^[3–9]Sb³⁺, ^[3–12]Te⁴⁺, ^[6–9]I⁵⁺	^[6–8]Tl⁺, ^[3]Sn²⁺, ^[5,7]Pb²⁺	Sn²⁺, As³⁺, Sb³⁺, Se⁴⁺; possibly In⁺, Ge²⁺, Te⁴⁺, Bi³⁺	χ _N³⁻ < χ_O²⁻; optimal match of atomic orbital energies shifted to cations of lower electronegativity

Minor: ^[3–12]Tl⁺, ^[3–12]Pb²⁺, ^[3–10,12]Bi³⁺

Polymerization: ^[4] M ⁶⁺ configuration
^[4]Si⁴⁺, ^[4]Ge⁴⁺, ^[4]Ti⁴⁺, ^[4]Cr⁴⁺	^[4]Mo⁶⁺, ^[4]W⁶⁺	^[4]S⁶⁺, ^[4]Se⁶⁺, ^[4]Cr⁶⁺	Cation OS/CN ratio of 1.5 required for prolific polymerization via^[2]N³⁻, vs. a ratio of 1 for ^[2]O²⁻

Includes cations of high oxidation state (OS) that may be challenging to achieve experimentally.