Tetranuclear carbonylfluorohydroxymanganese(I) clusters, [Mn4(CO)3Fx(OH)4-x]

1980 ◽  
Vol 33 (8) ◽  
pp. 1659 ◽  
Author(s):  
E Horn ◽  
MR Snow ◽  
PC Zeleny
Keyword(s):  
Edge Length ◽  
The Other ◽  
Individual Species ◽  
Dichloromethane Solution ◽  
Full Matrix ◽  
Crystallographic Symmetry ◽  
Corrected Data ◽  
R Value ◽  
The Individual ◽  
Hydroxy Groups

Reactions of Mn(CO)5X(X = Cl, Br) with TIF or AgF in dichloromethane solution give the cluster species [Mn4(CO)12Fx(OH)4-x]. The TlF reactions give predominantly the species with x = 1 and 2 and the AgF reaction the species with x = 2 and 3. The individual species x = 0-4 can be identified in the mass spectrum. The x = 2 product from the AgF abstraction can be separated from the x = 3 one by crystallization over benzene to yield the pure solvate [Mn4(CO)12F2(OH)2],-2C6H6. The infrared OH stretch in this compound (3543 cm-1) shifts to higher frequency (3620 cm-1) on desolvation (100�C, 0.1 mmHg), confirming OH...π hydrogen bonding to benzene, and explains the purification mechanism. Crystals of the TlF product are cubic, space group Pn3m, with a 11.277(1) Ǻ. The absorption corrected data gave a conventional R value of 0.043 on full- matrix least-squares refinement. This product is predominantly the monofluoride species but the other differently substituted ones form isomorphous crystals. The molecules are cubane-type clusters of Mn(CO)3 groups at one set of corners interpenetrated with fluoro or hydroxy groups at the other set and exhibit crystallographic symmetry 43m. These interpenetrating tetrahedra have edge length of 3.199(1) and 2.529(3) Ǻ respectively consistent with values expected for limiting non-bonding contacts.

A tetranuclear carbonyl fluoro rhenium(I) cluster, [Re(CO)3F]4,4H2O

1981 ◽  
Vol 34 (4) ◽  
pp. 737 ◽  
Author(s):  
E Horn ◽  
MR Snow
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
The Other ◽  
Water Molecules ◽  
Molecular Symmetry ◽  
Group 14 ◽  
Full Matrix ◽  
Abstraction Reaction ◽  
R Value ◽  
Silver Fluoride

The title compound has been prepared from Re(CO)5Br by a bromide-abstraction reaction with silver fluoride. It completes the series of known halide clusters of the type [Re(CO)3X]4 (where X = halide). The crystals are tetragonal, space group 14, with a 11.716(5), c 8.988(3) �, and Z 2. The structure was refined by full-matrix least-squares to an R value of 0.027 for 1380 observed reflections. The molecules are cubane-type clusters of Re(CO)3 groups at one set of corners interpenetrated with fluorine atoms at the other set. The clusters exhibit the molecular symmetry 43m. Each of the fluorine atoms is involved in μ3 type bridging with the rhenium atoms at an average bonding distance of 2.200(5) �. The clusters are held together by hydrogen bonding of fluoride to water molecules.

Coordinated fluoride in rhenium(I) carbonyl complexes

1984 ◽  
Vol 37 (1) ◽  
pp. 35 ◽  
Author(s):  
E Horn ◽  
MR Snow
Keyword(s):  
Hydrogen Bonding ◽  
Least Squares ◽  
Mass Spectra ◽  
Structural Data ◽  
Monoclinic Space Group ◽  
Carbonyl Complexes ◽  
Full Matrix ◽  
Space Group ◽  
Corrected Data ◽  
R Value

Bromide abstraction from the complexes Re(CO)3L2Br (where L = SbPh3 and L2 = bpy, dpe, tmen)* by AgF2H gives the corresponding fluoro compounds Re(CO)3L2F. Mass spectra and structural data show that the fluoride in these complexes is coordinated to the metal. The structures of Re(CO)3(tmen)F and [Re(CO)3(tmen)F]2H.HOBF3 are reported here. Crystals of Re(CO)3(tmen)F are monoclinic, space group P21/c, with a 8.202(2), b 13.115(9), c 12.048(4) � and β 102 24(3)�. A full-matrix least-squares refinement by using the absorption corrected data gave a conventional R value of 0.041. [Re(CO)3(tmen)F]2H.HOBF3 also crystallizes in the space group P21/c. The lattice parameters are: a 17.495(2), b 10.772(2), c 15.447(1) � and β ( 101.409(8)�. The final R value of a blocked least-squares calculation converged at 0.061. In these two complexes the simple Re-F distance is 2.040(4) �, in Re(CO)3(tmen)F. The Re-F distance is increased to 2.236(10)�, as a result of hydrogen bonding between the fluoride and HOBF3 in the latter compound.

Crystal Structure of α-Zn2V2O7

1973 ◽  
Vol 51 (7) ◽  
pp. 1004-1009 ◽  
Author(s):  
Ramanathan Gopal ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Bond Length ◽  
Fold Axis ◽  
Full Matrix ◽  
X Ray ◽  
R Value ◽  
The Individual ◽  
Zn Ions ◽  
Oxygen Atoms

α-Zn2V2O7 is monoclinic with lattice parameters a = 7.429(5), b = 8.340(3), c = 10.098(3) Å, β = 111.37(5)°, Z = 4 and space group C2/c. The structure was refined using a full matrix least-squares with 1034 reflections measured with a quarter-circle General Electric automatic X-ray diffractometer to a final R value of 0.066. The anion consists of a pair of VO4 tetrahedra sharing an oxygen atom which lies on a two-fold axis. The bridging V—O bond length is 1.775(4) Å while the three independent terminal ones are 1.728(4), 1.704(7), and 1.658(8) Å long. These bond lengths are consistent with the charge character around the individual oxygen atoms. The Zn ions are coordinated to five oxygen atoms with Zn—O bonds ranging from 1.973 to 2.088°Å. The structure is similar to that of α-CU2P2O7 and transforms to the thortvietite structure at about 615 °C.

Response of woody eastern Canadian forest weeds to fall foliar treatments of glyphosate and triclopyr herbicides

1993 ◽  
Vol 23 (12) ◽  
pp. 2490-2498 ◽  
Author(s):  
D.G. Pitt ◽  
D.G. Thompson ◽  
N.J. Payne ◽  
E.G. Kettela
Keyword(s):  
Sugar Maple ◽  
The Other ◽  
Individual Species ◽  
White Ash ◽  
Regression Curves ◽  
Growing Seasons ◽  
Crown Volume ◽  
Coefficients Of Variation ◽  
The Individual ◽  
Glyphosate Formulations

Second-season post-treatment efficacy data are presented for a New Brunswick field study comparing three formulations of glyphosate (VISION®, MON14420, and TOUCHDOWN®) and a single formulation of triclopyr (RELEASE®). Five rates of each herbicide were broadcast applied to a 2-year-old clearcut in early September. Two growing seasons after treatment, percent control values (based on total woody crown area) ranged from 21% at glyphosate rates < 0.25 × label maximum to more than 80% at rates ≥ 0.75 × label maximum. Coefficients of variation for percent control values decreased from 104% at the lower glyphosate rates to 9% at the higher rates. Total woody control provided by triclopyr was generally equivalent to that of glyphosate at rates < 0.5 × label maximum. Beyond this rate, percent control values for triclopyr averaged only 59% and coefficients of variation remained high (40%). At the individual-species level, the three glyphosate formulations provided greater crown volume reduction than triclopyr for white ash (Fraxinusamericana L.), beech (Fagusgrandifolia Ehrh.), hazel (Coryluscornuta Marsh.), and sugar maple (Acersaccharum Marsh.). Control of mountain maple (Acerspicatum Lam.) by TOUCHDOWN® was found to be slightly inferior to that of the other two glyphosate formulations. Control of elderberry (Sambucuspubens Michx.) by MON14420 was inferior to that of the other three herbicides. Nonlinear regression curves relating second-season control and herbicide dose are presented as a guide for silvicultural use.

Tris(N,N-dialkyldithiocarbamato-S,S')thiotungsten(VI) Complexes and the X-Ray Crystal Structure of [WS(S2CNEt2)3]BF4

1994 ◽  
Vol 47 (11) ◽  
pp. 2075 ◽  
Author(s):  
CG Young ◽  
TO Kocaba ◽  
M Sadek ◽  
RTC Brownlee ◽  
ERT Tiekink
Keyword(s):  
Variable Temperature ◽  
The Other ◽  
Axial Position ◽  
Monoclinic Space Group ◽  
Equatorial Position ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dithiocarbamate Ligand ◽  
R Value

The orange, diamagnetic compounds [WS(S2CNR2)3]X(R = Me, X- = BF4-, BPh4-;R = Et, X- =BF4-) were prepared by reacting WSCl4 and Me3SiS2CNR2 in dichloromethane, followed by metathesis with NaX in methanol. The compounds were characterized by elemental analysis, infrared and variable-temperature 1H n.m.r. spectroscopy and X-ray crystallography. Crystals of [WS(S2CNEt2)3] BF4 were monoclinic, space group P21/a with a 12.293(1), b 17.229(5), c 14.257(2) Ǻ,β 113.69(1)°, V 2765(2) Ǻ3 and Dc = 1.796 g cm-3 for Z = 4. The structure was solved by the Patterson method and refined by a full-matrix least-squares procedure, 3961data being used, to a conventional R value of 0.039 ( Rw = 0.040). The seven-coordinate cation possesses a pentagonal-bipyramidal geometry; the terminal thio ligand [W=S 2.127(2)Ǻ] occupies an axial position, a unique dithiocarbamate ligand spans the other axial position and an equatorial position while the two other dithiocarbamate ligands occupy the four remaining equatorial sites.

Sedimentation and electrophoresis of interacting substances. I. Idealized boundary shape for a single substance aggregating reversibly

1959 ◽  
Vol 250 (1262) ◽  
pp. 377-388 ◽  
Keyword(s):  
Strong Dependence ◽  
Leading Edge ◽  
Solute Concentration ◽  
Sedimentation Velocity ◽  
Model System ◽  
The Other ◽  
Individual Species ◽  
Boundary Shape ◽  
Single Substance ◽  
The Individual

The effect of differential transport on the gradient of concentration across a boundary is calculated for a substance existing in solution as a series of aggregates in mutual equilibrium. General equations are derived which are then used to construct schlieren patterns for a model system in order to illustrate the types of pattern to which aggregation can give rise. It is shown that in electrophoresis experiments the boundary in one limb is diffuse, and in the other hyper-sharp. In sedimentation the boundary is diffuse in general, but may have a hypersharp leading edge if there is a strong dependence o f the sedimentation velocity of the individual species on solute concentration. Although it is not possible for true resolution to occur at the boundary of a system in which equilibrium is maintained, the shapes of the schlieren patterns of the diffuse boundaries can be such as to give the impression that partial resolution is occurring. It means then that aggregates composed of more than two molecules are present and that at least one type of higher aggregate is strongly accentuated.

scholarly journals The 37-year dynamics of a subalpine passerine bird community, with special emphasis on the influence of environmental temperature and Epirrita autumnata cycles

Ornis Svecica ◽  
2004 ◽  
Vol 14 (3) ◽  
pp. 63-106 ◽  
Author(s):  
Anders Enemar ◽  
Bengt Sjöstrand ◽  
Göran Andersson ◽  
Ted Von Proschwitz
Keyword(s):  
Species Turnover ◽  
Bird Community ◽  
Passerine Bird ◽  
Mean Value ◽  
The Other ◽  
Individual Species ◽  
Epirrita Autumnata ◽  
The Mean ◽  
One Year ◽  
The Individual

The breeding passerine bird community of 9 km2 of a primeval subalpine birch forest in Swedish Lapland was censused yearly from 1963 through 1999. The community density remained stable, fluctuating around a mean value of 403 ± 85 territories/km2. Species richness increased by an average of one species every four years. Twenty species made up 98% of the community and Phylloscopus trochilus (40%) and Fringilla montifringilla (19%) remained the dominant species. The species turnover rate between successive seasons was on average 30%. The mean temperatures in June and July were positively correlated to the community density two years and one year later, respectively, less so for the densities of the individual species. Fringilla montifringilla increased in density during the first two years of each Epirrita autumnata caterpillar outbreak, whereas the other species responded only weakly or not at all. All species tended to fluctuate in parallel (no significant opposite trends) which together with the other results suggests that the investigated bird community is far from saturated.

scholarly journals Incidence of salmonella infection in animals in England and Wales, 1968–1974

1977 ◽  
Vol 78 (1) ◽  
pp. 43-56 ◽  
Author(s):  
W. J. Sojka ◽  
C. Wray ◽  
Jean Shreeve ◽  
A. J. Benson
Keyword(s):  
Annual Incidence ◽  
The Other ◽  
Individual Species ◽  
Salmonella Infection ◽  
England And Wales ◽  
The Third ◽  
The Individual

SUMMARYOf a total of 23,609 incidents of salmonella infection reported during the period 1968–74, 20,326 occurred in cattle, 1744 in poultry and other birds, 675 in sheep, 558 in pigs and 306 in other species of animals.Despite the large number of serotypes isolated (153), 88% of incidents were due to only two serotypes: S. dublin (15,929 incidents of which 15,446 occurred in cattle) and S. typhimurium (4842 incidents of which 3785 occurred in cattle and 732 in birds).S. choleraesuis was the third (314 incidents which with only 5 exceptions occurred in pigs) and S. abortusovis (243 incidents all in sheep) was the fourth most commonly isolated serotype. The following six serotypes were each recorded in more than 100 incidents: S. newport (177), S. agona (170), S. virchow (169), S. anatum (152), S. enteritidis (150) and S. montevideo (111). The other 143 serotypes accounted for only 5·8% of total incidents.The trends of annual incidence of salmonella infection in cattle, sheep, pigs, poultry and other birds during the 17-year period 1958–74 and the distribution of the main serotypes in the individual species of animals from 1968 to 1974 are discussed.

Structure of the Species in the Copper (II)–L-Histidine System

1973 ◽  
Vol 51 (21) ◽  
pp. 3563-3571 ◽  
Author(s):  
Theo P. A. Kruck ◽  
Bibudhendra Sarkar
Keyword(s):  
Species Distribution ◽  
Equilibrium Mixture ◽  
The Other ◽  
Individual Species ◽  
Complex Species ◽  
System A ◽  
Multiple Species ◽  
Ph Range ◽  
The Individual ◽  
Total Absorbance

The presence of simultaneously existing multiple species were taken into account in interpreting the structures of the complex species in the Cu(II)–L-histidine system. A refined proton displacement technique was utilized for structure elucidation of the species in solution. The absorbance and the molar extinction of the individual species were computed from the total absorbance and the species distribution over the pH range studied. The i.r. spectra of L-histidine and Cu(II)–L-histidine in D2O were obtained as a function of pD. They were interpreted in view of the species detected in a given pH range. The results of the species distribution as a function of pH, proton displacement, visible spectra of the individual species, and infrared data, were all combined to make structural interpretations. The following modes of metal coordination were proposed for the major species in the Cu(II)–L-histidine system: MHA, O(carboxyl) and N(imidazole); MH2A2, O(carboxyl) and N(amino) in both L-histidines; MA, O(carboxyl), N(imidazole), and N(amino); MHA2O(carboxyl), N(imidazole), and N(amino) in one L-histidine and O(carboxyl) and N(amino) in the other; MA2, O(carboxyl). N(imidazole), and N(amino) in both L-histidines, or O(carboxyl), N(imidazole), and N(amino) in one L-histidine and N(amino) and N(imidazole) in the other or an equilibrium mixture of both structures.

Writing in Aphasia Rehabilitation: Cursive vs Manuscript

1976 ◽  
Vol 41 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Daniel R. Boone ◽  
Harold M. Friedman
Keyword(s):  
Correct Response ◽  
The Other ◽  
Read Aloud ◽  
Writing Style ◽  
Reading And Writing ◽  
Manual Responses ◽  
Significant Difference ◽  
Written Form ◽  
The Individual ◽  
Read Number

Reading and writing performance was observed in 30 adult aphasic patients to determine whether there was a significant difference when stimuli and manual responses were varied in the written form: cursive versus manuscript. Patients were asked to read aloud 10 words written cursively and 10 words written in manuscript form. They were then asked to write on dictation 10 word responses using cursive writing and 10 words using manuscript writing. Number of words correctly read, number of words correctly written, and number of letters correctly written in the proper sequence were tallied for both cursive and manuscript writing tasks for each patient. Results indicated no significant difference in correct response between cursive and manuscript writing style for these aphasic patients as a group; however, it was noted that individual patients varied widely in their success using one writing form over the other. It appeared that since neither writing form showed better facilitation of performance, the writing style used should be determined according to the individual patient’s own preference and best performance.

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