Elongated dihydrogen complexes: what remains of the H–H Bond? #chempaperaday 208

Most transition metal dihydrogen complexes have an H-H distance less than 1 Angstrom. The rest of the complexes have longer H-H bond distances making them what is called "elongated dihydrogen" complexes. Of course if the distance is larger than 1.5 they become dihydride compounds.

http://pubs.rsc.org/en/content/articlelanding/2004/cs/b304879a#!divAbstract

In this short review, there is a lot and much useful information for those who want to learn more about these interesting complexes. Because it is difficult to resolve the crystal structures containing these ligands, there are a few methods to characterize them. Probably the simplest method is to use HD and measure the coupling constant and then plug it in in this formula :

There are ten "representative" complexes in the article that really help you to get a better understanding. I like the idea of listing these complexes and giving details about them. I think more authors should try this type of writing. Most review articles only cite other papers and avoid giving detailed information which makes following the paper really hard in some cases.