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A Model for Trivalent Actinides in Media Containing High Carbonate Concentrations − Structural Characterization of the Lanthanide Tetracarbonate [Co(NH 3 ) 6 ][Na(μ‐H 2 O)(H 2 O) 4 ] 2 [Ho(CO 3 ) 4 ]·4H 2 O
Author(s) -
Bond Deborah L.,
Clark David L.,
Donohoe Robert J.,
Gordon John C.,
Gordon Pamela L.,
Keogh D. Webster,
Scott Brian L.,
Tait C. Drew,
Watkin John G.
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200111)2001:11<2921::aid-ejic2921>3.0.co;2-2
Subject(s) - chemistry , crystallography , carbonate , molecule , denticity , aqueous solution , raman spectroscopy , actinide , lanthanide , tetrahedral molecular geometry , crystal structure , ion , inorganic chemistry , optics , physics , organic chemistry
The identity of the limiting Ho III species in aqueous solutions with high carbonate concentrations has been determined to be Ho(CO 3 ) 4 5− . Single crystals of [Co(NH 3 ) 6 ][Na(μ−H 2 O)(H 2 O) 4 ] 2 [Ho(CO 3 ) 4 ]·4H 2 O were obtained by the addition of [Co(NH 3 ) 6 ] 3+ to an aqueous 0.04 M solution of Ho III in 2.1 M Na 2 CO 3 . The asymmetric unit contains the anion, [Ho(CO 3 ) 4 ] 5− , a [Co(NH 3 ) 6 ] 3+ cation and two Na + cations, which are bound to H 2 O molecules in an edge‐sharing bioctahedral geometry. The [Ho(CO 3 ) 4 ] 5− anion is eight coordinate with four bidentate carbonate ligands bound to the Ho atom. The molecule has essentially C 2 v symmetry with two coplanar carbonates making a vane, which is perpendicular to a similar vane produced by the other two carbonate ligands. An alternative way to this view molecule is through the geometry of the C atoms, which are found in a distorted tetrahedron. The average Ho−O distance was determined to be 2.361(5) Å, while the average Ho−C distance was 2.784(6) Å. The IR and Raman spectra were determined in both the solid state and solution in order to confirm the solution speciation. The Raman data show a single CO 3 2− stretch for the solid at 1062 cm −1 . The solution data show multiple peaks with the most prominent being at 1048 cm −1 , which is consistent with the literature reports of an equilibrium mixture. The IR data for the solids confirm the X‐ray results showing bidentate carbonate ligands by the splitting of the ν 3 band of the CO 3 2− . The crystal data for [Co(NH 3 ) 6 ][Na(μ‐H 2 O)(H 2 O) 4 ] 2 [Ho(CO 3 ) 4 ]·4H 2 O are as follows: monoclinic space group P 2/ n , a = 8.7091(5) Å, b = 10.8744(6) Å, c = 15.7971(9) Å, β = 93.117(1)°, Z = 2, R 1 = 0.0307, wR 2 = 0.0756.