Synthesis and Structural Characterization of a Series of Dimeric Metal(II) Imido Complexes {M(μ-NAr#)}2[M = Ge, Sn, Pb; Ar#= C6H3-2,6-(C6H2-2,4,6-Me3)2] and the Related Monomeric Primary Amido Derivatives M{N(H)Ar#}2(M = Ge, Sn, Pb): Spectroscopic Manifestations of Secondary Metal−Ligand Interactions

2010 ◽  
Vol 49 (15) ◽  
pp. 7097-7105 ◽  
Author(s):  
William A. Merrill ◽  
Robert J. Wright ◽  
Corneliu S. Stanciu ◽  
Marilyn M. Olmstead ◽  
James C. Fettinger ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Imido Complexes ◽  
Ligand Interactions ◽  
Metal Ligand

Structural characterization of GABARAP–ligand interactions

2009 ◽  
Vol 5 (6) ◽  
pp. 575 ◽  
Author(s):  
Yvonne Thielmann ◽  
Oliver H. Weiergräber ◽  
Jeannine Mohrlüder ◽  
Dieter Willbold
Keyword(s):  
Structural Characterization ◽  
Ligand Interactions

Effects of the [OC6F5] moiety upon structural geometry: crystal structures of half-sandwich tantalum(V) aryloxide complexes from reaction of Cp*Ta(N t Bu)(CH2 R)2 with pentafluorophenol

2011 ◽  
Vol 67 (5) ◽  
pp. 416-424 ◽  
Author(s):  
Jacqueline M. Cole ◽  
Michael C. W. Chan ◽  
Vernon C. Gibson ◽  
Judith A. K. Howard
Keyword(s):  
Crystal Structure ◽  
Structural Characterization ◽  
Twist Angle ◽  
The Other ◽  
Structural Geometry ◽  
Factors Affecting ◽  
Imido Complexes ◽  
Half Sandwich ◽  
Oxide Derivative

The synthesis, chemical and structural characterization of a series of pentamethylcyclopentadienyl (Cp*) tantalum imido complexes and aryloxide derivatives are presented. Specifically, the imido complexes Cp*Ta(N t Bu)(CH2 R)2, where R = Ph [dibenzyl(tert-butylamido) (η5-pentamethylcyclopentadienyl)tantalum(IV) (1)], Me2Ph [tert-butylamido)bis(2-methyl-2-phenylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (2)], CMe3 [(tert-butylamido)bis(2,2-dimethylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (3)], are reported. The crystal structure of (3) reveals α-agostic interactions with the Ta atom. The resulting increase in the tantalum core coordination improves electronic stability. As such it does not react with pentafluorophenol, in contrast to the other two reported imido complexes [(1) and (2)]. Addition of C6F5OH to (1) yields a dimeric aryl-oxide derivative, [Cp*Ta(CH2Ph)(OC6H5)(μ-O)]2 [di-μ-oxido-bis[benzyl(pentafluorophenolato) (η5-pentamethylcyclopentadienyl)tantalum(V)] (4)]. Its crystal structure reveals long Ta—O(C6H5) bonds but short oxo-bridging Ta—O bonds. This is explained by accounting for the fierce electronic competition for the vacant d π orbitals of the electrophilic TaV centre. Steric congestion around each metal is alleviated by a large twist angle (77.1°) between the benzyl and pentafluorophenyl ligands and the ordering of each of these groups into stacked pairs. The imido complex (2) reacts with C6F5OH to produce a mixture of Cp*Ta(OC6F5)4 [tetrakis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V) (5)] and [Cp*Ta(OC6F5)2(μ-O)]2 [di-μ-oxido-bis[bis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V)] (6)]. Steric congestion is offset in both cases by the twisting of its pentafluorophenyl ligands. Particularly strong electronic competition for the empty d π metal orbitals in (6) is reflected in its bond geometry, and owes itself to the more numerous electron-withdrawing pentafluorophenyl ligands. The balance of steric and electronic factors affecting the reactivity of Cp* tantalum imido based complexes with pentafluorophenol is therefore addressed.

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 582-583
Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Structural Characterization ◽  
Negative Staining ◽  
Low Speed ◽  
Thin Sectioning ◽  
Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

Structural characterization of the PPIase domain of FKBP51, a cochaperone of human Hsp90

2011 ◽  
Vol 44 (06) ◽  
Author(s):  
A Bracher ◽  
C Kozany ◽  
AK Thost ◽  
F Hausch
Keyword(s):  
Structural Characterization ◽  
Ppiase Domain

Structural characterization of dendrobine-type sesquiterpene alkaloids from the stems of Dendrobium nobile using LC-MS/MS

Planta Medica ◽  
2014 ◽  
Vol 80 (10) ◽  
Author(s):  
YH Wang ◽  
B Avula ◽  
N Abe ◽  
F Wei ◽  
M Wang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Dendrobium Nobile

Structural characterization of monacolin compounds from red yeast rice by liquid chromatography and tandem mass

Planta Medica ◽  
2015 ◽  
Vol 81 (11) ◽  
Author(s):  
YH Wang ◽  
B Avula ◽  
Z Zhang ◽  
M Wang ◽  
S Sagi ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Structural Characterization ◽  
Red Yeast Rice ◽  
Tandem Mass ◽  
Red Yeast
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