Thursday, October 29, 2015

Isostructural Molecular and Surface Mimics of the Active Sites of the Industrial WO3/SiO2 Metathesis Catalysts #chempaperaday 243

"Silica-supported tungsten oxide has become a key catalyst of the petrochemical industry as part of the Lummus OCT process, allowing the production of propylene through the ethenolysis of butenes.(1, 2) Despite the now well-accepted Chauvin mechanism, alkylidenes and metallacyclobutane intermediates have however never been observed in such systems"
So, it is always worth trying to synthesize well defined supported mimics of these.
A very short but a really good paper. Great examples of synthetic work and problem solving. I am loving it.

Evaluating Molecular Cobalt Complexes for the Conversion of N2 to NH3 #chempaperaday 242

Another example of nitrogen fixation by a cobalt complex. Very similar to what I just posted. There are a few tables where you can see the comparison of similar complexes. I found it very useful.

Diiron Bridged-Thiolate Complexes That Bind N2 at the FeIIFeII, FeIIFeI, and FeIFeI Redox States #chempaperaday 241

We all know that nitrogenase cofactors have iron AND sulfur. But, if you look at the literature it's not very often that you see an iron complex with sulfur donors that bind N2. Here is a great example that ALSO yields ammonia!

Characterization of an Fe≡N–NH2 Intermediate Relevant to Catalytic N2 Reduction to NH3 #chempaperaday 240

The first of the series of papers I will post from Peters lab this week. I absolutely love their projects and synthetic work.

In this paper, they used several spectroscopic techniques to identify an important intermediate and it was determined that the complex is "a doubly protonated hydrazido(2−) complex featuring an Fe-to-N triple bond." The structure and bonding probably similar to an intermediate in O2 reduction by Fe.

The utilization of ceria in industrial catalysis #chempaperaday 239

Another heterogeneous catalysis paper that I read. This time, it's about ceria (CeO2). Ceria is the most important rare earth oxide in industrial catalysis and due to its price and not much investigated properties, I think it is a good starting point to find some important catalytic applications.

Design, Preparation, and Characterization of Zn and Cu Metallopeptides... #chempaperaday 238

If you are following my blog, you are well aware that I am very much interested in bioinorganic chemistry and metallopeptides are one of my favorite topics. Here is an example of a cationic framework helping the metal to be more active for DNA cleavage.

Cr–Cr Quintuple Bonds: Ligand Topology and Interplay Between Metal–Metal and Metal–Ligand Bonding #chempaperaday 237

"The difference between Cr−Cr quadruple and quintuple bonds is not just another weak δ bond."

This is very nice study to find some correlation between several bond metrics, ligand types etc. and the M-M bond distance and bond order. As you can imagine, for some systems, there IS nice correlations. For example, systems like Cr2L4, weaker Cr-L interactions yield to stronger Cr-Cr bonds. I found this paper very useful to design new ligands to maybe break the record short distance and discover some unique properties.

Why Is Uranyl Formohydroxamate Red? #chempaperaday 236

Colors tell a lot in inorganic chemistry. While most of the reported U(VI) complexes are red, the complex in question here was reported as red. So, the reason was investigated and two factors were found to explain the color. If you are interested, you can read it here:

Thursday, October 8, 2015

Why Combustions Are Always Exothermic ? #chempaperaday 235

A very simple question, but incredibly hard to answer without thinking about it. In fact, I don't think I can give a correct answer without looking up. Even then, I would probably be wrong. Luckily, this great article will help me in the future. It gives enough evidence and answers simple questions like "why fire is hot regardless of the fuel" and "why in spite of its high bond enthalpy, O2 is abundantly present in our atmosphere.?"

I printed this article and I will keep it as a reference and educational source for my own purposes.

Sunday, October 4, 2015

Oxidation State, A Long-Standing Issue! #chempaperaday 234

Oxidation state is both the simplest and the hardest concepts of chemistry. To be honest, sometimes (maybe more often than sometimes), I get confused too.  In fact, you can even find slightly different definitions of oxidation state depending on what you are trying to reach in the end. To be honest, I found this paper a little bit confusing in the beginning. It's not the author's fault of course. Once again, oxidation state is not really straightforward. Overall, I think it is a nice paper to read and a good summary of interesting examples.

BONUS : It's open access.

Improvements in the synthesis and understanding of the iodo-bridged intermediate en route to the Pt(IV) prodrug satraplatin #chempaperaday 233

Satraplatin is a Pt(IV) prodrug and the route to satraplatin is still in debate. In this article the authors propose a iodo-bridged intermediate and an improved synthesis to this intermediate. Really nice work and characterization methods.