Precious Serendipity

Serendipity often drives scientific inquiry.

Ask a famous scientist - Feynman, Archimedes, Fleming, to name a few beneficiaries - they'd tell you it's better to be lucky than good. But Pasteur's paraphrased "Fortune favors the prepared mind" spells things out more clearly; diving into the nitty-gritty of chemical transformations often brings up a chance pearl of wisdom.

Such is the case for a recent JACS ASAP, out of the Wang group at Xiamen University in China. Let's set the stage: the scientists attempt to create a stabilized bimetallic cluster compound from gold, silver, and hemilabile P-N ligands. When the starting Ag-Au complex meets acetonitrile and methanol, something interesting occurs: a dimeric crystalline compound forms, bridged by two fully deprotonated acetonitriles!

Those golden pyramids are pretty schnazzy.
Source: JACS | Wang group

So, why am I so excited?

1. That's a CCN (3-) anion stuck in there! What if you could, say, build a tetra-substituted carbon center just by adding electrophiles in sequence?

2. C-H activation of sp3 bonds = hard. Especially at room temp.
Well, there's (technically) 6 sp3 C-H bonds missing in that complex!

3. The authors note that water forms as the reaction progresses. Most nitriles, in the presence of Au/Ag catalysts and water, will hydrate to form amides. Not so here.

4. The authors point out that a gold oxo intermediate must be present for the cluster to form. They also point out that similar gold oxo catalysts (and silver oxide bases) pop up in the literature. Perhaps crazy intermediates like this commonly arise in gold-catalyzed reactions?

The best part? Studies like this always leave you with more questions than answers.
Perfect fodder for future projects.

Elemental Beer

It's October, which means falling leaves, football, cider, und Oktoberfest. Cracking open my copy of the latest WIRED Magazine last night, I came face-to-face with a full-page ad for Bud Light Platinum:

Source: Anheuser-Busch

Now, I understand the idea: an expensive noble metal speaks to the supposed quality of this latest beer offering. But it got me thinking - How often do you see element-themed noms de booze?

Let’s examine the obvious first. For the last few NFL seasons, Coors Light has run a promo with a speeding train called “The Silver Bullet.” Care for something else? Maybe some Molsen Golden, or anything from the Coors brewery in Golden, CO. With the help of Google and Beer Advocate, we’ll stray a little farther afield for a few more periodic pints…

Dieu du Ciel Helium, Montreal, Canada

Lithia Beer, West Bend, WI

Mount Carbon Beer, Pottsville, PA

(I know it’s cheating a bit, but how about the nitrogen Guinness rocket / widget?)

Gordon Finest Titanium, Scotland

Barney Gumble holds a
'Hassium Hefeweizen'

Fuji No Kina Vanadium Beer, Nigata Brewery, Japan

Carling Chrome, Molson Coors UK

Iron City Beer, Pittsburgh, PA

OMB Copper, Mecklenberg, NC

Arsenic, Belgium

Tsingtao Selenium-Riched 8, China

Krypton Rye PA, Victoria, BC, Canada

Tungsten Strong Lager, England

Tin Roof Beer, New Orleans, LA

There’s a brewery in Richland, WA called Atomic Ale, located just down the street from an historical plutonium reactor*. The ambience has apparently rubbed off; their beer roster includes Plutonium Porter, Seaborgium 106 Scottish Ale, Dysprosium DunkelWeisen, and Proton Pale Ale.

Surprisingly, several apt elements seem to have no brew to call their own. Quaff a Rubidium Red? A Lanthanum lambic, or maybe a Germanium Doppelböck? Americium Amber, Indium Pale Ale, Barium Brown…these things just write themselves!

Readers, have I missed any other elemental beers? Have any suggestions for ones you’d like to see?

Update (10/6/12) - How about elemental breweries? Telluride Brewing Co., Element Brewing Co.

*Several folks have commented that I might be grossly oversimplifying the importance of the Hanford site, akin to calling dinosaurs "those prehistoric dragons," or the Super Bowl "the last football game of the season." My apologies; I'll look deeper into it, and plan a follow-up post.

Hi Ho, Silver! (Benzoate)

Ever feel déjà vu? You know, that feeling of having been somewhere before, or crossing a black cat twice?

Carbon dioxide - Silver benzoate "puts a ring on it"
Source: Yamada, et.al. ACIEE, 2012

I've been stalked lately by a certain catalytic reagent: silver (I) benzoate. It's everywhere! Here, Charette's using it for C-H activation, with a little dash of Pd, to produce heterocyclic drug leads. Here, Toste's group turns up the selectivity on a gold hydroamination. Just this week, Yamada and coworkers showed lactone formation via carbon dioxide fixation (see above), using a bit of pressure, some base, and...you guessed it, silver benzoate.


Makes me wonder: Did I somehow miss the signs? How long has this reagent been flying under my radar?

In 1957, the Lone Ranger
ruled the Silver Screen
Source: lonerangerfanclub.com

Quite a while, it seems. Name reaction buffs - have you heard of the Prévost? First developed in the 1930s, it produces an anti vicinal diester, forming two new C-O bonds from opposite directions on neighboring carbons. Later investigations into the "wet Prévost" reaction favored cis diols; not too shabby when you consider that the related osmium or iodonium variants were still several decades away.


In its heyday, the Prévost helped synthesize steroids, alkaloids, and polymers, and found its way into the hands of a Who's Who of the O-Chem 'golden age': Woodward, Fieser, Carothers, Winstein, Streitweiser, Gilman, Djerassi, Fries, Benkeser, Sondheimer, van Tamelen, and Witkop. Perhaps you're more of a mechanisms person? Check out this sweet ¹⁸O labeling work, courtesy of a young University of Washington chemist named Ken Wiberg (1957).

What about silver benzoate makes it so darn useful for these oxidations? First, you have a d¹⁰ late metal species, which loves to coordinate to π-bonds (alkenes, alkynes, allenes). Second, the softer nature of the resonance-stabilized benzoate might switch on different catalytic pathways, say, changing from inner- to outer-sphere. Finally, to the benzoate itself: our buddy Ken showed that it adds twice, producing a transient 5-membered, cyclic species that ultimately permits the second benzoate addition.