Preparation and spectroscopic properties of three new actinide (IV) borohydrides

Technical Report · Sat Dec 01 04:00:00 EST 1979

DOI:https://doi.org/10.2172/5507647· OSTI ID:5507647

Banks, R H

New tetrakis-borohydrides of Pa, Np, and Pu have been synthesized. The crystal structure of Pa(BH/sub 4/)/sub 4/ is isostructural to those of Th(BH/sub 4/)/sub 4/ and U(BH/sub 4/)/sub 4/ and is of the tetragonal space group P4/sub 3/2/sub 1/2, where a = 7.53 (3) A, c = 13.22 (5) A, and Z = 4. Its calculated density is 2.57 gm-cm/sup -3/. Pa(BH/sub 4/)/sub 4/ is an orange, air-sensitive compound which is soluble in THF and sublimes at 55/sup 0/ in vacuum. Due to the thermal instabilities of Np(BH/sub 4/)/sub 4/ and Pu(BH/sub 4/)/sub 4/, their reaction temperatures are maintained at 0/sup 0/ and the compounds must be stored at low temperature. Low temperature x-ray diffraction studies have shown that Np(BH/sub 4/)/sub 4/ and Pu(BH/sub 4/)/sub 4/ are isomorphous and exhibit a unique crystal structure which is very similar to that of Zr(BH/sub 4/)/sub 4/. The details of this new structure were determined by single crystal x-ray diffraction methods at 130K for Np(BH/sub 4/)/sub 4/. Neptunium borohydride is monomeric and crystallizes into the tetragonal space group P4/sub 2//nmc, where a = 8.559 (9) A, c = 6.017 (9) A, and Z = 2. The 12 coordinate Np atom is triply hydrogen-bridged bonded to four terminal BH/sub 4//sup -/ groups disposed tetrahedrally around it giving Np-B distances of 2.46 (3) A. Solid-state, low temperature infrared (25-7400 cm/sup -1/) and Raman (100-2600 cm/sup -1/) spectra were taken for Np(BH/sub 4/)/sub 4/ and Np(BD/sub 4/)/sub 4/. A normal coordinate analysis was carried out using the assigned fundamental frequencies obtained from the spectra and determined a reasonable set of force constants and calculated values for the frequencies of the unobserved T/sub 1/ modes. Based on results of the analysis, isotopic impurity, overtone, and combination bands were identified in the infrared spectra.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5507647
• Report Number(s): LBL-10292
• 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 COMPOUNDS
BOROHYDRIDES
BORON COMPOUNDS
CHEMICAL PREPARATION
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
HYDROGEN COMPOUNDS
LATTICE PARAMETERS
NEPTUNIUM COMPOUNDS
PLUTONIUM COMPOUNDS
PROTACTINIUM COMPOUNDS
SCATTERING
SYNTHESIS
TRANSURANIUM COMPOUNDS
X-RAY DIFFRACTION