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. Related tridentate anionic ligands include trispyrazolylborate and cyclopentadienyl anions.[1]

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

  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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