The word agostic was coined about 30 years or so ago to describe how certain two-point bonding occurs. The Greek word agostos (ἀγοστός) means the "flat of the hand" and is apparently very rare and only occurs once in Homer's Iliad (it took me some doing to find that Greek link). The metaphor is that the bonding resembles a man's bent arm with the flat of one hand on a hip such that there are two points of arm attachment to the body: a strong one at the shoulder and a weaker one between the hand and the hip.
Recently, an old friend of mine co-discovered and reported on a remarkable new compound which crystallized in two subtly different ways, one analogous to having the palm on the hip and the other with the back of the hand on the hip. The two isomers are termed "agostomers" and also show the interesting property that one agostomer crystal is orange and the other one is blue. Here's a depiction:
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*stands with arms akimbo* Thank you, that's interesting, what little I understood. Will you speak a little about the practical uses of agostomers, or where they hope to lead?
Speaking of a bad chemical reaction...
I call it egodeficio.
Deborah: I am more fond of Anglo-Saxon terms than Greek ones; In retrospect, akimbomers would be a better term. I'll suggest it to my friend.
Agostomers are so new that like a newborn baby they have no practical utility. This work got attention because of the striking color difference which appear only in the solid state. Dissolve either and you get the same purple solution.
Agostic bonding by itself is useful for designing catalysts where you want the hand to leave the hip readily to bare the hip to other molecules. Agostic bonding is common for alkene polymerization catalysts--the lovely chemical species that make plastics.
Thanks, chick.
You're welcome, deborah. By suggesting an even better word, you proved the title's point.
Love it when you talk chemistry to us, El Pollo.
Deborah: Another possible use could be devising a new method to detect rates of interconversion between such agostomers. I mentioned that in solution you see just a purple color -- but that may just be a visual average or in other words a superposition of two colors orange and blue. A spectrometer able to resolve and detect the two colors might in fact "see" the two different agostomers in solution. In this way, their interconversion in solution could be measured and, as a function of temperature, could yield the energy required to do so.
Thanks again, chick.
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