Approaches to alkane functionalization with Tp′Pt and (nacnac)Pt reagents

2009 ◽  
Vol 87 (1) ◽  
pp. 288-296 ◽  
Author(s):  
Nathan M West ◽  
Joseph L Templeton
Keyword(s):  
Oxidation State ◽  
Coordination Mode ◽  
Reductive Elimination ◽  
Binding Modes ◽  
Acid Base ◽  
The Past ◽  
Alkane Functionalization ◽  
Tightly Coupled ◽  
Scorpionate Ligand ◽  
Alkyl Hydrides

In this perspective article we give an overview of our studies of C–H activation with platinum over the past decade. The scorpionate ligand Tp′ (Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate) has exhibited the ability to stabilize both Pt(IV) and Pt(II) complexes due to flexibility between κ3 and κ2 binding modes. Control of the Tp′ coordination mode and Pt oxidation state is tightly coupled with acid/base chemistry. This ability allowed us to model a spectrum of intermediates in C–H activation reactions, including Pt(IV) alkyl hydrides, five-coordinate Pt(IV) silyl hydrides, and Pt(II) benzene complexes. We have been able to observe sturdy Pt(II) benzene complexes and probe their equilibria with the respective C–H activated Pt(IV) species in the presence of an added ligand. We have also taken steps toward functionalizing hydrocarbons with Tp′Pt by dehydrogenation of alkanes and by arylation of olefins. We have recently turned to bidentate nacnac (nacnac = N-phenyl-β-enamineimine) ligands in the hopes of catalytically functionalizing hydrocarbons.Key words: C–H activation, reductive elimination, Tp′Pt, five-coordinate, β-diiminate.

scholarly journals A Survey on Edge Performance Benchmarking

2021 ◽  
Vol 54 (3) ◽  
pp. 1-33
Author(s):  
Blesson Varghese ◽  
Nan Wang ◽  
David Bermbach ◽  
Cheol-Ho Hong ◽  
Eyal De Lara ◽  
...  
Keyword(s):  
Large Scale ◽  
Future Internet ◽  
Coupled Systems ◽  
Operational Conditions ◽  
Loosely Coupled ◽  
Performance Benchmarking ◽  
The Past ◽  
Geographically Dispersed ◽  
Tightly Coupled ◽  
History Of

Edge computing is the next Internet frontier that will leverage computing resources located near users, sensors, and data stores to provide more responsive services. Therefore, it is envisioned that a large-scale, geographically dispersed, and resource-rich distributed system will emerge and play a key role in the future Internet. However, given the loosely coupled nature of such complex systems, their operational conditions are expected to change significantly over time. In this context, the performance characteristics of such systems will need to be captured rapidly, which is referred to as performance benchmarking, for application deployment, resource orchestration, and adaptive decision-making. Edge performance benchmarking is a nascent research avenue that has started gaining momentum over the past five years. This article first reviews articles published over the past three decades to trace the history of performance benchmarking from tightly coupled to loosely coupled systems. It then systematically classifies previous research to identify the system under test, techniques analyzed, and benchmark runtime in edge performance benchmarking.

SUITABILITY OF ACID-SOLUBLE AND ACID-INSOLUBLE LEATHER FRACTIONS IN RADIOCARBON DATING

Radiocarbon ◽  
2020 ◽  
pp. 1-8
Author(s):  
Alyssa M Tate ◽  
Brittany Hundman ◽  
Jonathan Heile
Keyword(s):  
Radiocarbon Dating ◽  
Insoluble Fraction ◽  
Economic Life ◽  
Chemical Pretreatment ◽  
Acid Base ◽  
The Past ◽  
Acid Soluble Collagen ◽  
Method Of Production ◽  
Insight Into

ABSTRACT Leather has been produced by a variety of methods throughout human history, providing researchers unique insight into multiple facets of social and economic life in the past. Archaeologically recovered leather is often fragile and poorly preserved, leading to the use of various conservation and restoration efforts that may include the application of fats, oils, or waxes. Such additives introduce exogenous carbon to the leather, contaminating the specimen. These contaminants, in addition to those accumulated during interment, must be removed through chemical pretreatment prior to radiocarbon (14C) dating to ensure accurate dating. DirectAMS utilizes organic solvents, acid-base-acid (ABA) and gelatinization for all leather samples. Collagen yield from leather samples is variable due to the method of production and the quality of preservation. However, evaluating the acid-soluble collagen fraction, when available, provides the most accurate 14C dates for leather samples. In instances where gelatinization does not yield sufficient material, the resulting acid-insoluble fraction may be dated. Here we examine the effectiveness of the combined organic solvent and ABA pretreatment with gelatinization for leather samples, as well as the suitability of the acid-insoluble fraction for 14C dating.

DUNCAN'S DISEASES OF METABOLISM: ENDOCRINOLOGY, ed 7. Edited by Philip K. Bondy and Leon E. Rosenberg. Philadelphia, WB Saunders Co, 1974, $26; 736 pp

PEDIATRICS ◽  
1977 ◽  
Vol 59 (5) ◽  
pp. 794-794
Author(s):  
Lester F. Soyka
Keyword(s):  
Clinical Endocrinology ◽  
Normal Structure ◽  
Acid Base Balance ◽  
Acid Base ◽  
Telephone Directory ◽  
The Past ◽  
Big City ◽  
Recent Developments ◽  
Base Balance ◽  
And Function

The endocrinology section of Duncan's Diseases of Metabolism comprises 736 pages, or about 44% of the total text. The division of this seventh edition of a classic text in the field is perhaps a logical expression of the splitting of endocrinology from metabolism as each field has grown tremendously in the past decade. The endocrinology portion is compact and easy to use because of this division, aided by the employment of thin, though substantial paper and small, but easily readable type. These combine to avoid the feeling of consulting a big-city telephone directory, which is so common with use of many of the standard textbooks of today. The illustrations are generally excellent and the 54-page index, which covers both sections of the book, is unusually thorough. As in all textbooks, many sections are outdated before they appear in print. Although the editors, Philip K. Bondy and Leon E. Rosenberg, propose to avoid this by means of a "last-minute" addendum, only two of the 13 chapters bear such, and one of these lists only three references, all dating to 1972. The other recent-developments section is longer and more helpful. The content is essentially that of general clinical endocrinology, each chapter using the standard approach of considering normal structure and function and then diseases in a gland arrangement, starting with the hypothalamus and traveling downward to the testis and ovary. A small chapter on acid-base balance seems out of place, whereas those on nonendocrine-secreting tumors and serotonin and the carcinoid syndrome are useful extensions of the scope of endocrinology.

NiII, CuII and ZnII complexes with a sterically hindered scorpionate ligand (TpmsPh) and catalytic application in the diasteroselective nitroaldol (Henry) reaction

2014 ◽  
Vol 43 (40) ◽  
pp. 15192-15200 ◽  
Author(s):  
Bruno G. M. Rocha ◽  
Tatiana C. O. Mac Leod ◽  
M. Fátima C. Guedes da Silva ◽  
Konstantin V. Luzyanin ◽  
Luísa M. D. R. S. Martins ◽  
...  
Keyword(s):  
Coordination Mode ◽  
Henry Reaction ◽  
Catalytic Application ◽  
Nitroaldol Reaction ◽  
Sterically Hindered ◽  
Scorpionate Ligand

The bulky (TpmsPh)− adapts its coordination mode to the electronic and steric preferences of the NiII, CuII or ZnII centre forming complexes which catalyse the nitroaldol reaction.

A New Perfluorinated F21-Tp Scorpionate Ligand: Enhanced Alkane Functionalization by Carbene Insertion with (F21-Tp)M Catalysts (M = Cu, Ag)

2008 ◽  
Vol 27 (18) ◽  
pp. 4779-4787 ◽  
Author(s):  
Emmanuelle Despagnet-Ayoub ◽  
Kane Jacob ◽  
Laure Vendier ◽  
Michel Etienne ◽  
Eleuterio Álvarez ◽  
...  
Keyword(s):  
Alkane Functionalization ◽  
Carbene Insertion ◽  
Scorpionate Ligand

scholarly journals Metrical Oxidation States of 1,4-Diazadiene (DAD) Derived Ligands

2020 ◽  
Author(s):  
F.J. de Zwart ◽  
Bente Reus ◽  
Annechien A.H. Laporte ◽  
Vivek Sinha ◽  
Bas de Bruin
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Oxidation State ◽  
Transition Metal Complexes ◽  
Coordination Mode ◽  
Chemical Reactivity ◽  
Accurate Determination ◽  
Oxidation States ◽  
Wide Range ◽  
Ligand Bond

The conventional method of assigning formal oxidation states (FOS) to metals and ligands is an important tool for understanding and predicting chemical reactivity, in particular in catalysis research. For complexes containing redox-noninnocent ligands, the oxidation state of the ligand can be ambiguous (i.e. their spectroscopic oxidation state can differ from the formal oxidation state), and thus frustrates the assignment of the oxidation state of the metal. A quantitative correlation between empirical metric data of redox active ligands and their oxidation states using a metrical oxidation state (MOS) model has been developed for catecholate and aminophenolate derived ligands by Brown. In the present work, we present a MOS model for 1,4-diazabutadiene (DAD<sup>n</sup>) ligands. The model is based on a similar approach as reported by Brown, correlating the intra-ligand bond lengths of the DAD<sup>n</sup> moiety in a quantitative manner to the MOS using geometrical information from X-ray structures in the Cambridge Crystallographic Data Center (CCDC) database. However, accurate determination of the MOS of these ligands turned-out to be dependent the coordination mode of the DAD<sup>2-</sup> moiety, which can adopt both a planar <i>κ<sup>2</sup></i>-<i>N<sub>2</sub></i>-geometry and a <i>η<sup>4</sup></i>-<i>N<sub>2</sub></i>-<i>C<sub>2</sub></i> π-coordination mode in (transition) metal complexes in its doubly reduced, dianionic enediamide oxidation state. A reliable MOS model was developed taking the intrinsic differences in intra-ligand bond distances between these coordination modes of the DAD<sup>2‒</sup> ligand into account. Three different models were defined and tested using different geometric parameters (C=C→M distance, M-N-C angle, M-N-C-C torsion angle) to describe the C=C backbone coordination to the metal in the <i>η<sup>4</sup></i>-<i>N<sub>2</sub></i>-<i>C<sub>2</sub></i> π-coordination mode of the DAD<sup>2‒</sup> ligand. Statistical analysis revealed that the C=C→M distance best describes the <i>η<sup>4</sup></i>-<i>N<sub>2</sub></i>-<i>C<sub>2</sub></i> coordination mode, using a cut-off value of 2.46 Å for π-coordination. The developed MOS model was used to validate the oxidation state assignment of elements not contained within the training set (Sr, Yb and Ho), thus demonstrating the applicability of the MOS model to a wide range of complexes. Chromium complexes with complex electronic structures were also shown to be accurately described by MOS analysis. Furthermore, it is shown that a combination of MOS analysis and FOD calculations provide an inexpensive method to gain insight into the electronic structure of singlet spin state (S = 0) [M(trop<sub>2</sub>dad)] transition metal complexes showing multireference character.<br>

Lewis acid–base interactions between platinum(ii) diaryl complexes and bis(perfluorophenyl)zinc: strongly accelerated reductive elimination induced by a Z-type ligand

2016 ◽  
Vol 52 (43) ◽  
pp. 7039-7042 ◽  
Author(s):  
Allegra L. Liberman-Martin ◽  
Daniel S. Levine ◽  
Micah S. Ziegler ◽  
Robert G. Bergman ◽  
T. Don Tilley
Keyword(s):  
Lewis Acid ◽  
Reductive Elimination ◽  
Acid Base

Z-type interactions between bis(perfluorophenyl)zinc and platinum(ii) diaryl complexes supported by 1,10-phenanthroline (phen), 2,2′-bipyridine (bpy), and bis(dimethylphosphino)ethane (dmpe) ligands are reported.

scholarly journals The 100th anniversary of pH (1909-2009). Negative logarithms for measuring hydrogen ions: are they essential in medicine? Part I

2013 ◽  
pp. 147-155
Author(s):  
Francesco Sgambato ◽  
Sergio Prozzo ◽  
Ester Sgambato ◽  
Rosa Sgambato ◽  
Luca Milano
Keyword(s):  
Human Life ◽  
100Th Anniversary ◽  
Hydrogen Ion ◽  
Hydrogen Ions ◽  
Acid Base Balance ◽  
Acid Base ◽  
The Past ◽  
Scientific Papers ◽  
Base Balance ◽  
Ph Scale

Introduction: It has been 100 years since the concept of pH (1909-2009) was ‘‘invented’’ by the Danish chemist-mathematician Søren Peter Lauritz Sørensen (1868-1939) in the chemistry laboratories of the Carlsberg Brewery in Copenhagen. The anniversary provides an opportunity to examine the crucial importance in human life of acid-base balance. Materials and methods: The authors review the historical process that led to the creation of the pH scale, with citation of passages from the original work of Sørensen published 100 years ago. This is followed by a critical analysis of the debate regarding the use of logarithmstomeasure hydrogen ion concentrations based on data from scientific papers published over the past 50 years (1960-2010). Results and discussion: The authors conclude that the concept of acid-base balance can be approached and taught in a simpler, more exciting, and even pleasant fashion without using the infamous and abstruse Henderson-Hasselbalch equation. The whole rationale underlying the understanding and clinical application of this vital topic is clearly and unquestionably inherent simpler, more manageable formula introduced by Henderson (without logs), which is useful and quite adequate for use in medical education.

scholarly journals Acid-base/monomerdimer equilibrium of antitumor drug mitoxantrone and its DNA binding modes

2000 ◽  
Vol 40 (supplement) ◽  
pp. S94
Author(s):  
S. Takahashi ◽  
A. Toyama ◽  
H. Takeuchi
Keyword(s):  
Dna Binding ◽  
Antitumor Drug ◽  
Binding Modes ◽  
Acid Base
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