Lewis Acid/Base Interaction Matrix Database

Complex Anion Lewis Bases

High Symmetry Molecular Anions

Search for complex anion Lewis bases species in The Chemical Thesaurus

FMO Topology: Complex anion Lewis bases have a hypervalent central cation (boron, aluminium or heavy metal) saturated with anionic Lewis base ligands. Lewis octet and 18-electron rules are generally satisfied. The HOMO shows high spherical symmetry.
Charge: Negative.
HSAB: Intrinsically hard.
Chemistry:

Complex anion Lewis base species behave as charged hard spheres that form ionic charge-controlled complexes (ie act as non-nucleophilic counter ions), or they behave as donors of hard/soft ligands, X.

Ligand substitution – in which a nucleophilic Lewis Base displaces a nucleofugal ligand – is common and ligand symbiosis considerations/effects are very important.

There are four subclasses of complex anion Lewis base:

X = Halogen anion which gives rise to the synthetically useful non-basic, non-nucleophilic, non-interfering anionic spectator counter ions:

[BF4]    [SbF6]    [AsF6]    [FeBr4]

X = Hydride ion which gives rise to species which act as donors of nucleophilic hydride ion, [BH4] and [AlH4], as long as there is not a Brønsted Acidic proton available or H2 is generated.

M = Heavy metal (Fe or Cr as opposed to B or Al). Such complex anions are much studied in classical inorganic coordination chemistry. Transition metals centres often exhibit multiple oxidation states. These are better considered as type 23 Lewis acid/base complexes.

X = Oxygen heavy metal species with oxygen ligands are commonly used as oxidising agents.

Congeneric Series:

Families of ligand replacement congeneric series are common:

Complex anion Lewis base (generic)
Alkoxy aluminium hydride ion (generic)

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Alkoxy borohydride ion (generic)

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Alkyl aluminium hydride ion (generic)

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Alkyl borohydride ion (generic)

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Aluminium hexafluoride ion

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Aurocyanide ion

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Beryllate ion

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Bromine hexafluoride ion

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Chlorine tetrafluoride ion

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Dialkoxyaluminium hydride ion (generic)

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Dialkoxyborohydride ion (generic)

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Dialkylaluminium hydride ion (generic)

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Dialkylborohydride ion (generic)

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Dichlorosilver(I) ion

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Dicyanosilver(I) ion

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Germanium hexachloride dianion

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Germanium hexafluoride dianion

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Hexafluoroantimonate(V)

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Hexafluoroarsinate ion

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Hexafluoropalladium(IV)

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Hexafluoroplatinate ion

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Hexafluorosilicate ion

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Hexahydroiron(II) ion

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Iodine hexafluoride ion

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Iodine octafluoride ion

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Lead hexachloride dianion

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Lead hexafluoride dianion

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Manganate(V) ion

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Manganate(VI) ion

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Metaborate ion

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Orthoborate ion

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Pentahydrocobalt(I) ion

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Perbromate ion

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Perchlorate ion

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Periodate ion

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Permanganate ion

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Perxenate ion

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Phosphorus hexafluoride ion

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Platinum(II) tetrachloride ion

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Platinum(IV) hexachloride ion

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Scandium(III) hexafluoride ion

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Tetrabromoaluminate

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Tetrabromoborate

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Tetrabromoferrate ion

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Tetrachloroaluminium ion

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Tetrachloroborate

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Tetrachlorocopper(I) ion

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Tetrafluoroaluminate

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Tetrafluoroberyllate ion

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Tetrafluoroborate ion

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Tetrahydroaluminate

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Tetrahydroborate ion

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Tetrahydrogallinate ion

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Tetrahydroindate ion

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Tetrahydronickel(II) ion

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Tetrahydroxyaluminate ion

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Tetrahydroxyborate ion

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Tetrahydrozinc(II) ion

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Tetraiodoaluminate

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Tetraiodoborate

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Tin hexachloride dianion

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Tin hexafluoride dianion

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Tin pentachloride ion

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Trialkoxyaluminium hydride ion (generic)

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Trialkoxyborohydride ion (generic)

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Trialkylaluminium hydride ion (generic)

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Trialkylborohydride ion (generic)

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Vandate(V) ion

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Xenate ion

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Xenon heptafluoride ion

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Xenon octafluoride ion

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Zintl ion

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Poster
Nucleophiles & Bases

© Mark R. Leach 1999-


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