A new coordination mode for tris(2-carboxyethyl)phosphine: Synthesis, crystal structure and characterization of the mixed-valence Co(III)/Co(II)/Co(III) complex [Co{P(CH2CH2COO)2(CH2CH2COOH)}2]2[Co(H2O)4][Na2(H2O)4]Cl2 · 6H2O

Reaction of the water-soluble phosphine ligand tris(2-carboxyethyl)phosphine (TCEP) with cobalt(II) chloride to give a mixed-valence trimetallic Co(III)/Co(II)/Co(III) complex 1 in which the TCEP ligand adopts the previously unseen bidentate chelating binding mode to the metal center.