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Title: Electric deflection studies of rhodium clusters.

Abstract

No abstract prepared.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
914939
Report Number(s):
ANL/CHM/JA-58479
Journal ID: ISSN 0021-9606; JCPSA6; TRN: US200817%%23
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Chem. Phys.; Journal Volume: 126; Journal Issue: Mar. 14, 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; RHODIUM; MOLECULAR CLUSTERS; ELECTRIC FIELDS; DEFORMATION

Citation Formats

Knickelbein, M. B., Beyer, M. K., Chemistry, and Technische Univ. Berlin. Electric deflection studies of rhodium clusters.. United States: N. p., 2007. Web.
Knickelbein, M. B., Beyer, M. K., Chemistry, & Technische Univ. Berlin. Electric deflection studies of rhodium clusters.. United States.
Knickelbein, M. B., Beyer, M. K., Chemistry, and Technische Univ. Berlin. Wed . "Electric deflection studies of rhodium clusters.". United States. doi:.
@article{osti_914939,
title = {Electric deflection studies of rhodium clusters.},
author = {Knickelbein, M. B. and Beyer, M. K. and Chemistry and Technische Univ. Berlin},
abstractNote = {No abstract prepared.},
doi = {},
journal = {J. Chem. Phys.},
number = Mar. 14, 2007,
volume = 126,
place = {United States},
year = {Wed Mar 14 00:00:00 EDT 2007},
month = {Wed Mar 14 00:00:00 EDT 2007}
}
  • Molecular beams of a metastable electronic state of acetylene are prepared by electron impact excitation. The threshold for appearance of the state is near 4.5 eV. Electric deflection measurements of C/sub 2/H/sub 2/, C/sub 2/D/sub 2/, and HC/sub 2/D show the polarity of all three isotopes to be below the level of detectability. Comparison of the behavior of the metastable state with that of the ground electronic state of HC/sub 2/D, where polarity is readily established by electric deflection, is made. The polarity results are shown to establish a trans geometry for the observed state.
  • Tetrakis ((2,4,6-trimethylphenyl)porphyrinato)rhodium(II) ((TMP)Rh) and tetrakis((2,4,6-trilsopropylphenyl)-porphyrinato)rhodium(II) ((TTiPP)Rh) occur as low-spin d{sup 7} complexes with EPR parameters associated with a(d{sub xy}){sup 2}-(d{sub xz,yz}){sup 4}(d,2){sup 1} ground configuration. (por)Rh{sup II} species typically react as metalloradicals with a wide variety of substrates to give diamagnetic products; however, the use of increased porphyrin or substrate steric demands has permitted observation of paramagnetic 1:1 adducts. EPR spectra were used in examining features related to the electronic structure for a series of 1:1 five-coordinate complexes with nitrogen, phosphorus, arsenic, and carbon donor ligands. Each of the five-coordinate species is a low-spin d{sup 7} complex with the unpairedmore » electron occupying a d{sub z}2 MO (d{sub xy}d{sub xz}d{sub yz}){sup 6}-(d{sub z}{sup 2}){sup 1} ground configuration. The ligands form 1:1 adducts that have effective axial symmetry with the exceptions of CO, which has as a bent Rh-CO unit, and ethene, which has a symmetrical {pi} complex structure. Donor atom spin densities are estimated from ligand hyperfine coupling. Rhodium-103 hyperfine coupling is used in evaluating the rhodium 4d{sub x}2 (0.67) and Ss (0.02) spin density in the ethene {pi} complex, which combined with the total ethene C{sub 2p} (0.278) and C{sub 2s} (0.008) spin densities, determined from the ligand hyperfine coupling, accounts for most of the unpaired electron. Estimates of the d{sub z}2 to d{sub xz} and d{sub yz} energy separations for the series of 1:1 complexes illustrate the elevation of d{sub z}2 by {sigma} donor ligands and the combined lowering of d{sub xz}, d{sub yz}, and d{sub z}2 elevation by ligands with {pi} acceptor ability. 26 refs., 2 figs., 2 tabs.« less
  • Iridium octaethylporphyrin hydride, Ir(OEP)(H), reacts with carbon monoxide to form the carbonyl complex Ir(OEP)(H)(CO) at the same conditions where Rh(OEP)(H) reacts with CO to produce the metalloformyl complex Rh-(OEP)(CHO). Thermodynamic studies for these reactions are reported and discussed in terms of differences in the M-H and M-C bond energies and the acceptor properties of the five-coordinate metalloporphyrin hydride complexes.
  • The molecular strcutre of (HRh(P(OCH/sub 3/)/sub 3/)/sub 2/)/sub 3/ has been determined by using neutron diffraction techniques (T = 110 K). The trimeric rhodium complex is monoclinic, space group P2/sub 1/(C/sub 2//sup 2/, No. 4), with a = 10.792 (6) A, b = 13.438 (8) A, c = 13.438 (8) A, ..beta.. = 91.64 (4)/sup 0/, V/sub c/ = 1948.02 A/sup 3/, and d/sub calcd/ = 1.801 g cm/sup -3/ for Z = 2. The neutral molecule consists of a triangular array of Rh atoms each bonded in an approximately square-planar fashion to two terminal P(OCH/sub 3/)/sub 3/ groups andmore » two bridging hydride ligands. The Rh-Rh separations involving single hydrogen bridges are 2.803 (7), 2.780 (6), and 2.856 (8) A and the average Rh-H/sub b/ distance is 1.76 (3) A. The bridging Rh-H/sub b/ separations reported here are the first interactions to be characterized structurally with neutron crystallographic techniques (T = 110 K). A discussion of the origin of the structural distortion from planarity of the (HRhP/sub 2/)/sub 3/ cluster core is presented. 4 figures, 3 tables.« less