Kläui ligand

The Kläui ligand is the anion {(C5H5)Co[(CH3O)2PO]3}−. The ligand, popularized by Wolfgang Kläui, binds metals and metalloids via a facial O3 donor set.[1] Related tridentate and tripodal anionic ligands include trispyrazolylborates.

General structure of a metal center coordinated to a κ3-Kläui ligand.

The ligand is derived from the cationic complex of trimethylphosphite {(C5H5)Co[P(OCH3)3]3}2+ via an Arbuzov reaction.[2] Using other phosphites and other cyclopentadienyl ligands, a large variety of derivatives are possible. The parent acid {(C5H5)Co[(CH3O)2PO]3}H is highly soluble in water (270 g/100 mL). Its pKa is about 2. Many complexes have been described, including bis(chelate) complexes of the type {M[{(C5H5)Co[(CH3O)2PO]3}2]n+ (M = Co(II), Mn(II), Bi(III), etc.).[3]

## References[edit]

1. ^ Wolfgang Kläui, N. Mocigemba, A. Weber-Schuster, R. Bell, W. Frank, D. Mootz, W. Poll, and H. Wunderlich "[(C5H5)Co{P(O)(OH)2}3H]: A Novel Organometallic Tris-phosphonic Acid that Dissolves Glass to Form a Six-Coordinate Silicon Complex" Chemistry – European Journal 2002, Volume 8, pages 2335–2340. doi:10.1002/1521-3765(20020517)8:10<2335::AID-CHEM2335>3.0.CO;2-P
2. ^ W. Kläui, P. C. Kunz "Sodium (η5-Cyclopentadienyl)tris(dimethylphosphito-P)cobalt(III), Na[(C5H5)Co{P(O)(OMe)2}3]" Inorg. Synth., 2010 vol. 35, pp. 125–128. doi:10.1002/9780470651568.ch6
3. ^ Wolfgang Kläui, Heiko Otto, Werner Eberspach, Elke Buchholz "Die Michaelis-Arbusov-Reaktion als Zugang zu neuen Sauerstoff-Tripodliganden des Typs [C5R5M{P(O)(OCH3)2}3]−. Ligandfeldspektroskopische und koordinationschemische Charakterisierung der Liganden" Chemische Berichte 1982, Volume 115, Pages 1922–1933. doi:10.1002/cber.19821150522

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Cobalt compounds

Cobalt(I)|

* HCo(CO)4

Cobalt(II)|

* CoBr2
* Co(CN)2
* CoCO3
* CoC2O4
* CoCl2
* Co(ClO3)2
* CoF2
* Co(HCO2)2
* CoI2
* Co(NO3)2
* Co3(PO4)2
* Co(OAc)2
* CoGeO3
* CoO
* Co(OH)2
* CoS
* CO(SCN)2
* CoSO4
* CoSe
* Co3P2
* CoH2
* Co(C3H6O3)2
* C
24H
48CoO

* C
36H
70CoO

Cobalt(0, III)|

* CoSi
* CoGe

Cobalt(II, III)|

* Co3O4

Cobalt(III)|

* CoAs
* CoCl3
* Co(NO3)3
* Co2O3
* CoF3
* Co(OH)3
* LiCoO2

Cobalt(III,IV)|

* NaxCoO2

Cobalt(IV)|

* Cs2CoF6
* CoC28H44

Cobalt(V)|

* Na3CoO4

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