ChemInform Abstract: NMR AND IR STUDIES OF THE BONDING PROPERTIES OF THE ETHYLENE-RHODIUM COMPLEXES RHCL(C2H4)(L)(L′) (L = C2H4, CO, PR3, L′ = 2,6-LUTIDINE)

1978 ◽  
Vol 9 (47) ◽  
Author(s):  
A. MAISONNAT ◽  
R. POILBLANC
Keyword(s):  
Rhodium Complexes ◽  
Ir Studies ◽  
Bonding Properties

Nitrogen: Not a Dopant in Crystalline Si (C-Si), But an N-Type Dopant in A-Si:H, Why?

1994 ◽  
Vol 336 ◽  
Author(s):  
G. Lucovsky ◽  
M.J. Williams ◽  
S.S. He ◽  
S.M. Cho ◽  
Z. Jing ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Chemical Bonding ◽  
Nearest Neighbor ◽  
Hydrogenated Amorphous Silicon ◽  
Statistical Association ◽  
Ir Studies ◽  
Local Bonding ◽  
Bonding Properties ◽  
Hydrogenated Amorphous

ABSTRACTWe have incorporated N-atoms into hydrogenated amorphous silicon in the Si-rich alloy regime to ∼12 at.% N, and have observed a transition from n-type doping to alloying as the concentration of N-atoms is increased above about 5 at.%. By analogy with the local bonding arrangements of P-donors in n-doped a-Si:H, we attribute the doping to four-fold coordinated N-atoms with second neighbor H-atoms as in N+-Si-H linkages. The occurrence of these arrangements is supported by (i) IR studies which indicate a non-statistical association of N and H-atoms bonded to the same Si-atom, and (ii) a chemical bonding model in which the large effective electronegativies of four-fold coordinated N+ atoms and neutral O-atoms promote similar bonding properties with respect to their nearest-neighbor arrangements with Si and H atoms such as N+ (O) -Si-H linkages

Rh2Cl2(CO)4 adsorbed and tethered on gold powder: IR spectroscopic characterization and olefin hydrogenation activity

2001 ◽  
Vol 79 (5-6) ◽  
pp. 578-586 ◽  
Author(s):  
Hanrong Gao ◽  
Robert J Angelici
Keyword(s):  
Spectroscopic Characterization ◽  
Rhodium Complexes ◽  
Olefin Hydrogenation ◽  
Hydrogenation Catalysts ◽  
Gold Powder ◽  
Ir Studies ◽  
Major Species ◽  
Catalytically Active ◽  
Unidentified Species ◽  
Diffuse Reflectance Infrared

Catalysts were prepared by adsorbing Rh2Cl2(CO)4 directly on gold powder or on gold that contained the tethered ligands 2-(diphenylphosphino)ethane-1-thiol (DPET) or methyl 2-mercaptonicotinate (MMNT). Infrared (IR) studies (diffuse reflectance infrared Fourier transform (DRIFT)) of the catalyst Rh–Au prepared by adsorbing Rh2Cl2(CO)4 directly on Au indicate that a RhI(CO)2 species is present. IR studies of Rh–DPET-Au suggest that tethered cis-Rh(DPET)(CO)2Cl is the major species at relatively high Rh2Cl2(CO)4 loadings, but trans-Rh(DPET)2(CO)Cl is observable at low Rh2Cl2(CO)4 loadings. Spectral investigations of the catalyst Rh–MMNT-Au prepared by adsorbing Rh2Cl2(CO)4 on MMNT-Au suggest that tethered [cis-Rh(MMNT)2(CO)2]+Cl– and (or) Rh(MMNT)(CO)2Cl are the major species at low Rh2Cl2(CO)4 loadings, while a new unidentified species predominates at high Rh2Cl2(CO)4 loadings. All three catalysts are active 1-hexene hydrogenation catalysts under the mild conditions of 40°C and 1 atm of H2; they are much more active than Au powder or Rh2Cl2(CO)4 in solution. Of the three catalysts, Rh–Au is the most active with a maximum turnover frequency (TOF) of 800 mol H2 per mol Rh per min while its turnover (TO) is 29 600 mol H2 per mol Rh during a 2-hour run. Under the conditions of 1-hexene hydrogenation, the catalysts lose their CO ligands. Thus, it appears that a form of Rh metal on Au is the catalytically active species.Key words: catalysis, olefin hydrogenation, gold powder, tethered rhodium complexes, infrared studies, adsorption, rhodium complexes.

IR Studies of the Phase Transformation of Fe2O3 → Fe3O4by Magnetomechanical Activation

1997 ◽  
Vol 07 (C1) ◽  
pp. C1-615-C1-616 ◽  
Author(s):  
I. Jacyna-Onyszkiewicz ◽  
M. Grunwald-Wyspianska ◽  
W. A. Kaczmarek
Keyword(s):  
Phase Transformation ◽  
Ir Studies

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

Diphosphinoazine Rhodium(I) and Iridium(I) Complexes

2006 ◽  
Vol 71 (2) ◽  
pp. 197-206 ◽  
Author(s):  
Martin Pošta ◽  
Jan Čermák ◽  
Pavel Vojtíšek ◽  
Ivana Císařová
Keyword(s):  
Rhodium Complexes ◽  
Iridium Complexes ◽  
X Ray ◽  
First Time

The first rhodium complexes of diphosphinoazines [{RhCl(1,2-η:5,6-η-CH=CHCH2CH2CH=CHCH2CH2)}2 {μ-R2PCH2C(But)=NN=C(But)CH2PR2] (R = Ph, Cy, Pri) were prepared by cleavage of the bridge in chloro(cycloocta-1,5-diene)rhodium(I) dimer, the analogous iridium(I) complexes were also prepared for the first time. The X-ray structures of isostructural rhodium and iridium complexes with bis(dicyclohexylphosphino)pinacoloneazine were determined. Diphosphinoazine ligands in the complexes remained in (Z,Z) configuration bridging two RhCl(C8H12) units.

scholarly journals Platinum and rhodium complexes ligated by imidazolium-substituted phosphine as efficient and recyclable catalysts for hydrosilylation

RSC Advances ◽  
2019 ◽  
Vol 9 (50) ◽  
pp. 29396-29404 ◽  
Author(s):  
Magdalena Jankowska-Wajda ◽  
Olga Bartlewicz ◽  
Andrea Szpecht ◽  
Adrian Zajac ◽  
Marcin Smiglak ◽  
...  
Keyword(s):  
Rhodium Complexes ◽  
Recyclable Catalysts ◽  
High Yields

Platinum and rhodium complexes ligated by imidazolium substituted phosphine were obtained with high yields and applied as efficient catalysts.

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