Binary Transition Metal Dinitrogen Complexes. Part II. Matrix Infrared and Raman Spectra, Structure, and Bonding of Pt(N2)n (where n = 1–3)

1973 ◽  
Vol 51 (16) ◽  
pp. 2710-2721 ◽  
Author(s):  
E. P. Kündig ◽  
M. Moskovits ◽  
G. A. Ozin
Keyword(s):  
Spectral Lines ◽  
Site Symmetry ◽  
Carbonyl Complexes ◽  
Reaction Products ◽  
Substitutional Site ◽  
Planar Molecule ◽  
Infrared And Raman Spectroscopy ◽  
Dinitrogen Complexes ◽  
The Individual ◽  
Solid Argon

The products of the cocondensation reactions of Pt atoms with N2 at 4.2–10 °K are investigated by matrix isolation infrared and Raman spectroscopy and are shown to be binary dinitrogen complexes of the form Pt(N2)n. Examination of the reaction products in pure 14N2, in 14N2/15N2, in dilute 14N2/Ar, in 14N2/15N2/Ar as well as 14N2/14N/15N/15N2/Ar matrices establishes the stoichiometries of the complexes to be n = 1–3. Structural assignments can be made for the complexes Pt(N2) and Pt(N2)3 which contain end-on bonded dinitrogen and are found to be similar to the corresponding dinitrogen and carbonyl complexes of nickel and palladium. Pt(N2)2 appears to be the exception in this series of complexes, for which side-on bonded dinitrogen is proposed.On the basis of the Cotton–Kraihanzel force field of approximation and the isotope intensity sum rules, isotopic frequencies are computed for the NN stretching modes of the individual complexes and isotopic absorption intensities for Pt(N2)3 and are found to be in close agreement with the observed values. In the case of Pt(N2), the scrambled 14N15N isotope data establish that the dinitrogen ligand is bonded to the Pt atom in an end-on fashion. On the basis of its unusual spectroscopic behavior Pt(N2)2 is proposed to have sideways bonded dinitrogen ligands. Pt(N2)3 in solid α-N2 is found to be slightly distorted from a regular triangular planar molecule but appears to be regular D3h in solid argon. Calculations show that a substitutional site symmetry of C2 for Pt(N2)3 satisfactorily accounts for all the spectral lines observed for the complex in nitrogen. Comparisons are made within the group of binary dinitrogen complexes M(N2)n where n = 1–3 and with the corresponding binary carbonyl complexes M(CO)n. The relationship between the dinitrogen complexes NiN2, PdN2, and PtN2 and nitrogen chemisorbed on those same metals is discussed.

Binary Dinitrogen Complexes of Rhodium, Rh(N2)n (where n = 1–4), in Low Temperature Matrices

1973 ◽  
Vol 51 (20) ◽  
pp. 3332-3343 ◽  
Author(s):  
Geoffrey A. Ozin ◽  
Anthony Vander Voet
Keyword(s):  
Field Approximation ◽  
Spectral Lines ◽  
Site Symmetry ◽  
Reaction Products ◽  
Solid Nitrogen ◽  
Dinitrogen Complexes ◽  
The Individual ◽  
A Site ◽  
Solid Argon ◽  
The Relationship

The products of the cocondensation reactions of Rh atoms with N2 and N2/Ar mixtures at 10 °K are investigated by matrix isolation infrared spectroscopy and are shown to be binary dinitrogen complexes of the form Rh(N2)n. Examination of the reaction products in pure 14N2, 15N2, 14N2/15N2, and in dilute Ar/14N2, Ar/14N2/15N2, and Ar/14N2/14N15N/15N2 matrices establish the values of n to be 1–4. Isotopic frequencies are computed for the NN stretching modes of the individual dinitrogen complexes on the basis of the Cotton–Kraihanzel (C.K.) force field approximation and are found to be in close agreement with observed values. Trends in the best fit C.K. force constants for Rh(N2)n (n = 1–4) and the thermodynamic stabilities of the individual complexes as indicated by the function ΔHcn, a measure of the enthalpy of decomposition, are discussed. Comparisons are made between Ni(N2)n and Rh(N2)n (where n = 1–4). The structure of Rh(N2)4 in solid nitrogen is shown to be that of a distorted tetrahedron. Calculations show that a site symmetry of D2d for Rh(N2)4 satisfactorily accounts for all of the spectral lines observed for the complex in nitrogen. In solid argon, Rh(N2)4 appears to have an approximately regular tetrahedral structure. The relationship between RhN2 and N2 chemisorbed on Rh metal is discussed and compared with the analogous Ni–, Pd–, and Pt–nitrogen systems.

scholarly journals Thortveitite-type Tm2Si2O7

2014 ◽  
Vol 70 (7) ◽  
pp. i34-i35 ◽  
Author(s):  
Volker Kahlenberg ◽  
Paul Aichholzer
Keyword(s):  
Ambient Pressure ◽  
Point Group ◽  
Structure Type ◽  
Group Symmetry ◽  
Site Symmetry ◽  
Cation Site ◽  
Bond Lengths ◽  
Flux Synthesis ◽  
Distorted Octahedral ◽  
The Individual

Single crystals of dithulium disilicate, Tm2Si2O7, were obtained in flux synthesis experiments in the system SiO2–Tm2O3–LiF at ambient pressure. The compound belongs to the group of sorosilicates,i.e.it is based on [Si2O7]-units and crystallizes in the thortveitite (Sc2Si2O7) structure type. The Tm3+cation (site symmetry .2.) occupies a distorted octahedral site, with Tm—O bond lengths in the range 2.217 (4)–2.289 (4) Å. Each of the octahedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001). The individual [SiO4] tetrahedra are more regular,i.e.the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octahedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices.

Application of Gandolfi X-Ray Diffraction to the Characterization of Reaction Products from the Alteration of Simulated Nuclear Wastes

1980 ◽  
Vol 24 ◽  
pp. 265-269 ◽  
Author(s):  
C. A. F. Anderson ◽  
M. E. Zolensky ◽  
D. K. Smith ◽  
W. P. Freeborn ◽  
B. E. Scheetz
Keyword(s):  
Powder Diffraction ◽  
Individual Particle ◽  
Nuclear Wastes ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Individual ◽  
Individual Grains ◽  
Phase Characterization

AbstractAccurate phase characterization of the alteration products of rad-waste requires the separation and identification of scattered individual grains from among the bulk product. These grains are typically 5 to 100 μm in size. Bulk x-ray powder diffraction will normally not detect these minor phases, and even if the phase can be detected, it often may not be identifiable. The use of the Gandolfi technique with the individual particle not only facilitates the identification, but also allows the assignment of the identification to the specific grain.

scholarly journals Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

2010 ◽  
Vol 10 (4) ◽  
pp. 1969-1988 ◽  
Author(s):  
J. G. Slowik ◽  
A. Vlasenko ◽  
M. McGuire ◽  
G. J. Evans ◽  
J. P. D. Abbatt
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Relative Weight ◽  
Proton Transfer Reaction ◽  
Urban Site ◽  
Emission Sources ◽  
Reaction Products ◽  
Aerosol Mass ◽  
Direct Emission ◽  
The Individual

Abstract. During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analysed using positive matrix factorization (PMF). The two instruments were given balanced weight in the PMF analysis by the application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the instrument relative weight within each solution. The PMF analysis yielded a 6-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling and oxidative processing. The unified dataset provides information on emission sources (particle and VOC) and atmospheric processing that cannot be obtained from the datasets of the individual instruments: (1) apportionment of oxygenated VOCs to either direct emission sources or secondary reaction products; (2) improved correlation of oxygenated aerosol factors with photochemical age; and (3) increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

scholarly journals Direct observations of the atmospheric processing of Asian mineral dust

2007 ◽  
Vol 7 (5) ◽  
pp. 1213-1236 ◽  
Author(s):  
R. C. Sullivan ◽  
S. A. Guazzotti ◽  
D. A. Sodeman ◽  
K. A. Prather
Keyword(s):  
Mineral Dust ◽  
Heterogeneous Reaction ◽  
Field Studies ◽  
Dust Particles ◽  
Reaction Products ◽  
Transport Pathway ◽  
Air Masses ◽  
Atmospheric Processing ◽  
Acid Reaction ◽  
The Individual

Abstract. The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of the atmospheric processing of dust and generally agrees with simulated aerosol chemistry from the STEM-2K3 model. This series of novel results has important implications for improving the treatment of dust in global chemistry models and highlights a number of key processes that merit further investigation through laboratory and field studies.

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