Synthesis and crystal structure of UCp/sub 3/(C/sub 3/H/sub 3/N/sub 2/). A new mode of pyrazolate bonding

Journal Article · Fri May 01 04:00:00 EDT 1981 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic50219a043· OSTI ID:6447524

Eigenbrot, Jr, C W; Raymond, K N

The title compound has been prepared by the reaction of tricyclopentadienyluranium chloride (UCp/sub 3/Cl) and sodium pyrazolate (NaC/sub 3/H/sub 3/N/sub 2/) in tetrahydrofuran (THF). The compound has been characterized by its infrared, visible-near-IR, /sup 1/H NMR, and mass spectra and by single-crystal x-ray diffraction. The molecular structure consists of discrete UCp/sub 3/(C/sub 3/H/sub 3/N/sub 2/) molecules in which the uranium(IV) ion is coordinated by three eta/sup 5/-Cp rings in a nearly trigonal array similar to that of other lanthanide and actinide MCp/sub 3/X structures. However, unlike these other structures, an 11-coordinate geometry is achieved by having both the adjacent nitrogen atoms of the pyrazolate ring coordinate to the metal ion such that the local twofold axis of the pyrazolate ring and the local threefold axis of the UCp/sub 3/ fragment coincide. This is the first example of this type of endo-bidentate eta/sup 2/ coordination for the pyrazolate anion. Red-brown crystals from toluene conform to space group P2/sub 1//a (an alternate setting of P2/sub 1//c) with a = 14.295 (1) A, b= 8.383 (1) A, c = 14.282 (1) A, ..beta.. = 112.80 (1)/sup 0/, and four molecules per unit cell. For the 3631 independent reflections collected by counter methods with F/sup 2/ > 3sigma(F/sup 2/), the final weighted and unweighted R factors are both 3.14%. The U-N distances are 2.40 (1) and 2.36 (1) A. The average U-C distance of 2.76 A is consistent with that predicted for an 11-coordinate uranium (IV) cyclopentadienyl complex. The 90-MHz proton resonances of the Cp rings occur at -9.51 (35/sup 0/C), -11.59 (-10/sup 0/C), -14.22 (-50/sup 0/C), and -15.84 (-75/sup 0/C) ppM. Susceptibility studies from 5 to 80 K show a temperature-independent paramagnetism from 7.5 to 37.1 K; above this temperature ..mu../sub eff/ = 2.67 ..mu../sub B/.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6447524
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 20:5; ISSN INOCA
• 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
AZOLES
BOND ANGLE
BOND LENGTHS
CHEMICAL PREPARATION
COHERENT SCATTERING
COMPLEXES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DIMENSIONS
EXPERIMENTAL DATA
FURANS
HETEROCYCLIC COMPOUNDS
INFORMATION
INFRARED SPECTRA
LATTICE PARAMETERS
LENGTH
NMR SPECTRA
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PYRAZOLES
SCATTERING
SPECTRA
SYNTHESIS
TETRAHYDROFURAN
URANIUM COMPLEXES
X-RAY DIFFRACTION