Specific sequestering agents for the actinides. VI. Synthetic and structural chemistry of tetrakis(N-alkylalkanehydroxamato)thorium(IV) complexes

Journal Article · Wed Jun 17 04:00:00 EDT 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00402a019· OSTI ID:6454413

Smith, W L; Raymond, K N

Hydroxamate complexes of the actinides have been investigated as structural archetypes in the design of actinide-specific sequestering agents. The complexes Th((CH/sub 3/)/sub 2/CHN(O)O(O)R)/sub 4/ have been prepared (R = C(CH/sub 3/)/sub 3/ (1) or CH/sub 2/C(CH/sub 3/)/sub 3/ (2) The uranium(IV) analogue of 1 was also prepared. The tert-butyl groups of 1 dominate the stereochemistry of the complex by assuming a tetrahedral disposition around the metal. The coordination polyhedron of 1, which has 4 (S/sub 4/) crystallographic symmetry, is nearly cubic. The localization of charge on the nitrogen oxygen of the hydroxamate group makes this ligand unsymmetrical, and this gives rise to a 0.14-A difference in R(Th-O/sub N/) (2.357(3) A) and R(Th-O/sub C/) (2.492 (3) A). The sterically less constrained neopentyl derivative 2 shows a more typical eight-coordinate geometry - the D/sub 2d/ trigonal-faced (mmmm) dodecahedron. The average R(Th-O/sub N/) (2.36 (1) A) is again shorter than R(Th-O/sub C/) (2.46 (2) A). There is apparently no sorting of sites by ligand charge, since the O/sub N/ and O/sub C/ atoms are equally distributed between the A and B sites of the dodecahedron. Crystals of 1 conform to space group I4/sub 1//a with a = 17.338 (4) A and c = 12.706 (4) A. For 4 formula units per cell the calculated density d/sub calcd/ is 1.50 g cm/sup -3/ and d/sub obsd/ is 1.50 (1) g cm/sup -3/. Crystals of 2 conform to space group P1 with a = 9.777 (2) A, b = 14.633 (2) A, c = 18.515 (1) A, ..cap alpha.. = 74.061/sub 0/ (8), ..beta.. = 88.41 (1)/sup 0/, and ..gamma.. = 74.71 (2)/sup 0/. For 2 formula units per cell d/sub calcd/ = 1.30 g cm/sup -3/ and d/sub obsd/ = 1.19 g cm/sup -3/. Full-matrix least-squares refinement of both structures using all averaged, independent data with F/sup 2/ > 3sigma(F)/sup 2/ gave for 1 with 1798 data and 117 variables R = 0.027 and R/sub w/ = 0.032 and for 2 with 6978 data and 467 variables R = 0.034, R/sub w/ = 0.042. 10 figures, 11 tables.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6454413
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:12; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
AMINES
CHELATING AGENTS
COMPLEXES
CRYSTALLOGRAPHY
DATA
EXPERIMENTAL DATA
HYDROXAMIC ACIDS
HYDROXY COMPOUNDS
INFORMATION
LIGANDS
MOLECULAR STRUCTURE
NUMERICAL DATA
ORGANIC COMPOUNDS
STEREOCHEMISTRY
THORIUM COMPLEXES
URANIUM COMPLEXES