Is cyanide really a strong-field ligand?
Iron man or weakling? Ligand-field strengths are conveniently expressed by the empirical spectrochemical series. Although cyanide has been deeply entrenched as a strong-field ligand, a couple of recent examples cast doubt toward the position of this ligand, namely the high-spin (S = 2) states of [Cr(II)(CN)(5)](3-) and [Fe(II)(tpp)(CN)](-). tpp = meso-tetraphenylporphinate.
Nakamura
Mikio
M
Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan. mnakamu@med.toho-u.ac.jp
D002857:Chromium / Q000737:chemistry; D003486:Cyanides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry
D003486:Cyanides; D008024:Ligands; D009942:Organometallic Compounds; D002857:Chromium; D007501:Iron